38 results on '"Walton MK"'
Search Results
2. Sodium channels, GABAA receptors, and glutamate receptors develop sequentially on embryonic rat spinal cord cells
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Walton, MK, primary, Schaffner, AE, additional, and Barker, JL, additional
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- 1993
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3. Guest editorial. Milk depots, yarn trusses, and pediatric nurses.
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Barnsteiner JH and Walton MK
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- 2005
4. Defining Clinical Trial Estimands: A Practical Guide for Study Teams with Examples Based on a Psychiatric Disorder.
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Polverejan E, O'Kelly M, Hefting N, Norton JD, Lim P, and Walton MK
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- Humans, Research Design, Data Interpretation, Statistical, Models, Statistical, Depressive Disorder, Major drug therapy
- Abstract
While the ICH E9(R1) Addendum on "Estimands and Sensitivity Analysis in Clinical Trials" was released in late 2019, the widespread implementation of defining and reporting estimands across clinical trials is still in progress and the engagement of non-statistical functions in this process is also in progress. Case studies are sought after, especially those with documented clinical and regulatory feedback. This paper describes an interdisciplinary process for implementing the estimand framework, devised by the Estimands and Missing Data Working Group (a group with clinical, statistical, and regulatory representation) of the International Society for CNS Clinical Trials and Methodology. This process is illustrated by specific examples using various types of hypothetical trials evaluating a treatment for major depressive disorder. Each of the estimand examples follows the same template and features all steps of the proposed process, including identifying the trial stakeholder(s), the decisions they need to make about the investigated treatment in their specific role and the questions that would support their decision making. Each of the five strategies for handling intercurrent events are addressed in at least one example; the featured endpoints are also diverse, including continuous, binary and time to event. Several examples are presented that include specifications for a potential trial design, key trial implementation elements needed to address the estimand, and main and sensitivity estimator specifications. Ultimately this paper highlights the need to incorporate multi-disciplinary collaborations into implementing the ICH E9(R1) framework., (© 2023. The Author(s).)
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- 2023
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5. Identifying a core outcome set for pulmonary sarcoidosis research - the Foundation for Sarcoidosis Research - Sarcoidosis Clinical OUtcomes Taskforce (SCOUT).
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Harman NL, Gorst SL, Williamson PR, Barnathan ES, Baughman RP, Judson MA, Junk H, Kampstra NA, Sullivan EJ, Victorson DE, Walton MK, Al-Hakim T, Nabulsi H, Singh N, Grutters JC, and Culver DA
- Abstract
Background: Pulmonary sarcoidosis is a rare granulomatous disease of unknown aetiology. Heterogeneity in the outcomes measured in trials of treatment for pulmonary sarcoidosis has impacted on the ability to systematically compare findings, contributing to research inefficiency. The FSR-SCOUT study has aimed to address this heterogeneity by developing a core outcome set that represents a patient and health professional consensus on the most important outcomes to measure in future research for the treatment of pulmonary sarcoidosis., Research Design and Methods: systematic review of trial registries, narrative synthesis of published qualitative literature on the patient experience and results of a patient survey contributed to the development of a comprehensive list of outcomes that were rated in a two round online Delphi survey. The Delphi survey was completed by patients/carers and health professionals and the results discussed and ratified at an online consensus meeting., Results: 259 patients/carers and 51 health professionals completed both rounds of the Delphi survey. A pre-agreed definition of consensus was applied and the results discussed at an online consensus meeting attended by 17 patients and 7 health professionals). Fifteen outcomes, across five domains (physiological/clinical, treatment, resource use, quality of life, and death), reached the definition of consensus and were included in the core outcome set., Conclusions: The core outcome set represents a patient and health professional consensus on the most important outcomes for pulmonary sarcoidosis research. The use of the core outcome set in future trials, and efforts to validate its components, will enhance the relevance of trials to stakeholders and will increase the opportunity for the research to contribute to evidence synthesis., Competing Interests: NLH, SLG, PRW, RPB, MAJ, NAK, DEV, JCG, DAC have no competing interests. ESB is an employee of Janssen Research and Development, LLC, who has sponsored research studies in Sarcoidosis. EJS is an employee of Insmed Incorporated. MW employee of Janssen Research & Development. HJ is a sarcoidosis patient. TA-H, HN and NS were employed by the funder (The Foundation for Sarcoidosis Research) during the research., (Copyright: © 2021 SARCOIDOSIS VASCULITIS AND DIFFUSE LUNG DISEASES.)
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- 2022
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6. The adaptive designs CONSORT extension (ACE) statement: a checklist with explanation and elaboration guideline for reporting randomised trials that use an adaptive design.
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Dimairo M, Pallmann P, Wason J, Todd S, Jaki T, Julious SA, Mander AP, Weir CJ, Koenig F, Walton MK, Nicholl JP, Coates E, Biggs K, Hamasaki T, Proschan MA, Scott JA, Ando Y, Hind D, and Altman DG
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- Delphi Technique, Guidelines as Topic, Humans, Periodicals as Topic, Quality Control, Reproducibility of Results, Checklist standards, Consensus, Publishing standards, Randomized Controlled Trials as Topic standards, Research Design standards
- Abstract
Adaptive designs (ADs) allow pre-planned changes to an ongoing trial without compromising the validity of conclusions and it is essential to distinguish pre-planned from unplanned changes that may also occur. The reporting of ADs in randomised trials is inconsistent and needs improving. Incompletely reported AD randomised trials are difficult to reproduce and are hard to interpret and synthesise. This consequently hampers their ability to inform practice as well as future research and contributes to research waste. Better transparency and adequate reporting will enable the potential benefits of ADs to be realised.This extension to the Consolidated Standards Of Reporting Trials (CONSORT) 2010 statement was developed to enhance the reporting of randomised AD clinical trials. We developed an Adaptive designs CONSORT Extension (ACE) guideline through a two-stage Delphi process with input from multidisciplinary key stakeholders in clinical trials research in the public and private sectors from 21 countries, followed by a consensus meeting. Members of the CONSORT Group were involved during the development process.The paper presents the ACE checklists for AD randomised trial reports and abstracts, as well as an explanation with examples to aid the application of the guideline. The ACE checklist comprises seven new items, nine modified items, six unchanged items for which additional explanatory text clarifies further considerations for ADs, and 20 unchanged items not requiring further explanatory text. The ACE abstract checklist has one new item, one modified item, one unchanged item with additional explanatory text for ADs, and 15 unchanged items not requiring further explanatory text.The intention is to enhance transparency and improve reporting of AD randomised trials to improve the interpretability of their results and reproducibility of their methods, results and inference. We also hope indirectly to facilitate the much-needed knowledge transfer of innovative trial designs to maximise their potential benefits. In order to encourage its wide dissemination this article is freely accessible on the BMJ and Trials journal websites."To maximise the benefit to society, you need to not just do research but do it well" Douglas G Altman.
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- 2020
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7. Considerations for development of an evidence dossier to support the use of mobile sensor technology for clinical outcome assessments in clinical trials.
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Walton MK, Cappelleri JC, Byrom B, Goldsack JC, Eremenco S, Harris D, Potero E, Patel N, Flood E, and Daumer M
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- Clinical Trials as Topic standards, Drug Approval, Endpoint Determination standards, Humans, Outcome Assessment, Health Care, Parkinson Disease physiopathology, Practice Guidelines as Topic, Pulmonary Disease, Chronic Obstructive physiopathology, Remote Sensing Technology standards, Reproducibility of Results, Sarcopenia physiopathology, Clinical Trials as Topic methods, Endpoint Determination methods, Remote Sensing Technology methods, Wearable Electronic Devices standards
- Abstract
Background: Mobile sensors offer enormous potential for the collection of informative clinical endpoints in clinical trials to support regulatory decision making and product labelling. There are currently no specific guidelines on the information needed to enable regulators to review and accept proposed endpoints derived from mobile sensors for use in drug development trials., Objective: The purpose of this working group report is to recommend the structure and content of an evidence dossier intended to support whether a clinical endpoint derived from mobile sensor data is fit-for-purpose for use in regulatory submissions for drug approvals., Evidence Dossier: The structure and content of a dossier to provide evidence supporting the use of a sensor-derived clinical endpoint is described. Sections include clinical endpoint definition and positioning, the concept of interest, the context of use, clinical validation and interpretation, study implementation, and analytical validity with sensor performance verification in support of the selected sensor., Conclusions: In the absence of definitive regulatory guidance, this report provides a considered approach to compiling a comprehensive body of evidence to justify acceptance of mobile sensors for support of new drug applications., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2020
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8. Development process of a consensus-driven CONSORT extension for randomised trials using an adaptive design.
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Dimairo M, Coates E, Pallmann P, Todd S, Julious SA, Jaki T, Wason J, Mander AP, Weir CJ, Koenig F, Walton MK, Biggs K, Nicholl J, Hamasaki T, Proschan MA, Scott JA, Ando Y, Hind D, and Altman DG
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- Asia, Checklist, Consensus, Decision Support Techniques, Europe, Humans, Randomized Controlled Trials as Topic standards, Research Design standards
- Abstract
Background: Adequate reporting of adaptive designs (ADs) maximises their potential benefits in the conduct of clinical trials. Transparent reporting can help address some obstacles and concerns relating to the use of ADs. Currently, there are deficiencies in the reporting of AD trials. To overcome this, we have developed a consensus-driven extension to the CONSORT statement for randomised trials using an AD. This paper describes the processes and methods used to develop this extension rather than detailed explanation of the guideline., Methods: We developed the guideline in seven overlapping stages: 1) Building on prior research to inform the need for a guideline; 2) A scoping literature review to inform future stages; 3) Drafting the first checklist version involving an External Expert Panel; 4) A two-round Delphi process involving international, multidisciplinary, and cross-sector key stakeholders; 5) A consensus meeting to advise which reporting items to retain through voting, and to discuss the structure of what to include in the supporting explanation and elaboration (E&E) document; 6) Refining and finalising the checklist; and 7) Writing-up and dissemination of the E&E document. The CONSORT Executive Group oversaw the entire development process., Results: Delphi survey response rates were 94/143 (66%), 114/156 (73%), and 79/143 (55%) in rounds 1, 2, and across both rounds, respectively. Twenty-seven delegates from Europe, the USA, and Asia attended the consensus meeting. The main checklist has seven new and nine modified items and six unchanged items with expanded E&E text to clarify further considerations for ADs. The abstract checklist has one new and one modified item together with an unchanged item with expanded E&E text. The E&E document will describe the scope of the guideline, the definition of an AD, and some types of ADs and trial adaptations and explain each reporting item in detail including case studies., Conclusions: We hope that making the development processes, methods, and all supporting information that aided decision-making transparent will enhance the acceptability and quick uptake of the guideline. This will also help other groups when developing similar CONSORT extensions. The guideline is applicable to all randomised trials with an AD and contains minimum reporting requirements.
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- 2018
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9. Use of Mobile Devices to Measure Outcomes in Clinical Research, 2010-2016: A Systematic Literature Review.
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Perry B, Herrington W, Goldsack JC, Grandinetti CA, Vasisht KP, Landray MJ, Bataille L, DiCicco RA, Bradley C, Narayan A, Papadopoulos EJ, Sheth N, Skodacek K, Stem K, Strong TV, Walton MK, and Corneli A
- Abstract
Background: The use of mobile devices in clinical research has advanced substantially in recent years due to the rapid pace of technology development. With an overall aim of informing the future use of mobile devices in interventional clinical research to measure primary outcomes, we conducted a systematic review of the use of and clinical outcomes measured by mobile devices (mobile outcomes) in observational and interventional clinical research., Method: We conducted a PubMed search using a range of search terms to retrieve peer-reviewed articles on clinical research published between January 2010 and May 2016 in which mobile devices were used to measure study outcomes. We screened each publication for specific inclusion and exclusion criteria. We then identified and qualitatively summarized the use of mobile outcome assessments in clinical research, including the type and design of the study, therapeutic focus, type of mobile device(s) used, and specific mobile outcomes reported., Results: The search retrieved 2,530 potential articles of interest. After screening, 88 publications remained. Twenty-five percent of the publications ( n = 22) described mobile outcomes used in interventional research, and the rest ( n = 66) described observational clinical research. Thirteen therapeutic areas were represented. Five categories of mobile devices were identified: (1) inertial sensors, (2) biosensors, (3) pressure sensors and walkways, (4) medication adherence monitors, and (5) location monitors; inertial sensors/accelerometers were most common (reported in 86% of the publications). Among the variety of mobile outcomes, various assessments of physical activity were most common (reported in 74% of the publications). Other mobile outcomes included assessments of sleep, mobility, and pill adherence, as well as biomarkers assessed using a mobile device, including cardiac measures, glucose, gastric reflux, respiratory measures, and intensity of head-related injury., Conclusion: Mobile devices are being widely used in clinical research to assess outcomes, although their use in interventional research to assess therapeutic effectiveness is limited. For mobile devices to be used more frequently in pivotal interventional research - such as trials informing regulatory decision-making - more focus should be placed on: (1) consolidating the evidence supporting the clinical meaningfulness of specific mobile outcomes, and (2) standardizing the use of mobile devices in clinical research to measure specific mobile outcomes (e.g., data capture frequencies, placement of device). To that aim, this manuscript offers a broad overview of the various mobile outcome assessments currently used in observational and interventional research, and categorizes and consolidates this information for researchers interested in using mobile devices to assess outcomes in interventional research.
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- 2018
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10. Optimizing the analysis strategy for the CANVAS Program: A prespecified plan for the integrated analyses of the CANVAS and CANVAS-R trials.
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Neal B, Perkovic V, Mahaffey KW, Fulcher G, Erondu N, Desai M, Shaw W, Law G, Walton MK, Rosenthal N, de Zeeuw D, and Matthews DR
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- Aged, Biomarkers blood, Canagliflozin administration & dosage, Canagliflozin adverse effects, Cardiovascular Diseases complications, Cardiovascular Diseases epidemiology, Cardiovascular Diseases mortality, Cohort Studies, Diabetes Mellitus, Type 2 complications, Diabetes Mellitus, Type 2 metabolism, Diabetes Mellitus, Type 2 mortality, Diabetic Angiopathies epidemiology, Diabetic Angiopathies mortality, Diabetic Cardiomyopathies epidemiology, Diabetic Cardiomyopathies mortality, Dose-Response Relationship, Drug, Double-Blind Method, Drug Monitoring, Equivalence Trials as Topic, Female, Follow-Up Studies, Humans, Hypoglycemic Agents administration & dosage, Hypoglycemic Agents adverse effects, Male, Middle Aged, Mortality, Reproducibility of Results, Risk Factors, Sodium-Glucose Transporter 2 metabolism, Canagliflozin therapeutic use, Cardiovascular Diseases prevention & control, Diabetes Mellitus, Type 2 drug therapy, Diabetic Angiopathies prevention & control, Diabetic Cardiomyopathies prevention & control, Hypoglycemic Agents therapeutic use, Sodium-Glucose Transporter 2 Inhibitors
- Abstract
Two large cardiovascular outcome trials of canagliflozin, comprising the CANVAS Program, will complete in early 2017: the CANagliflozin cardioVascular Assessment Study (CANVAS) and the CANagliflozin cardioVascular Assessment Study-Renal (CANVAS-R). Accruing data for the sodium glucose co-transporter 2 (SGLT2) inhibitor class has identified questions and opportunities that were not apparent when the trials were designed. Accordingly, a series of modifications have been made to the planned analyses. These updates will ensure that the data from the CANVAS Program will maximize advances in scientific knowledge and patient care. The specification of the analysis strategy prior to knowledge of the trial results, their design by the independent scientific trial Steering Committee, the detailed a priori definition of the analysis plans, and the external review provided by the US Food and Drug Administration all provide maximally efficient and robust utilization of the data. The CANVAS Program should significantly advance our understanding of the effects of canagliflozin, and the broader SGLT2 inhibitor class, on a range of important efficacy and safety outcomes., (© 2017 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)
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- 2017
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11. Clinician-Reported Outcome Assessments of Treatment Benefit: Report of the ISPOR Clinical Outcome Assessment Emerging Good Practices Task Force.
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Powers JH 3rd, Patrick DL, Walton MK, Marquis P, Cano S, Hobart J, Isaac M, Vamvakas S, Slagle A, Molsen E, and Burke LB
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- Advisory Committees, Documentation standards, Health Status, Humans, Reproducibility of Results, Health Personnel, Outcome Assessment, Health Care methods, Outcome Assessment, Health Care standards, Research Design standards
- Abstract
A clinician-reported outcome (ClinRO) assessment is a type of clinical outcome assessment (COA). ClinRO assessments, like all COAs (patient-reported, observer-reported, or performance outcome assessments), are used to 1) measure patients' health status and 2) define end points that can be interpreted as treatment benefits of medical interventions on how patients feel, function, or survive in clinical trials. Like other COAs, ClinRO assessments can be influenced by human choices, judgment, or motivation. A ClinRO assessment is conducted and reported by a trained health care professional and requires specialized professional training to evaluate the patient's health status. This is the second of two reports by the ISPOR Clinical Outcomes Assessment-Emerging Good Practices for Outcomes Research Task Force. The first report provided an overview of COAs including definitions important for an understanding of COA measurement practices. This report focuses specifically on issues related to ClinRO assessments. In this report, we define three types of ClinRO assessments (readings, ratings, and clinician global assessments) and describe emerging good measurement practices in their development and evaluation. The good measurement practices include 1) defining the context of use; 2) identifying the concept of interest measured; 3) defining the intended treatment benefit on how patients feel, function, or survive reflected by the ClinRO assessment and evaluating the relationship between that intended treatment benefit and the concept of interest; 4) documenting content validity; 5) evaluating other measurement properties once content validity is established (including intra- and inter-rater reliability); 6) defining study objectives and end point(s) objectives, and defining study end points and placing study end points within the hierarchy of end points; 7) establishing interpretability in trial results; and 8) evaluating operational considerations for the implementation of ClinRO assessments used as end points in clinical trials. Applying good measurement practices to ClinRO assessment development and evaluation will lead to more efficient and accurate measurement of treatment effects. This is important beyond regulatory approval in that it provides evidence for the uptake of new interventions into clinical practice and provides justification to payers for reimbursement on the basis of the clearly demonstrated added value of the new intervention., (Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.)
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- 2017
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12. DIA's Adaptive Design Scientific Working Group (ADSWG): Best Practices Case Studies for "Less Well-understood" Adaptive Designs.
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Miller E, Gallo P, He W, Kammerman LA, Koury K, Maca J, Jiang Q, Walton MK, Wang C, Woo K, Fuller C, and Jemiai Y
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Adaptive design (AD) clinical trials use accumulating subject data to modify the parameters of the design of an ongoing study, without compromising the validity and integrity of the study. The 2010 US Food and Drug Administration (FDA) Draft Guidance on Adaptive Design Clinical Trials described a subset of 7 primary design types as "less well-understood." FDA defined these designs as those with limited regulatory experience. To better understand the properties of these less well-understood ADs and to promote their use when applicable, the Best Practices Subteam for DIA's Adaptive Design Scientific Working Group conducted an extensive nonsystematic search and reviewed trials from multiple sponsors who had employed these designs. Here, we review 10 specific case studies for which less well-understood ADs were employed and share feedback about their challenges and successes, as well as details about the regulatory interactions from these trials. We learned that these designs and associated statistical methodologies can make difficult research situations more amenable for study and, therefore, are needed in our toolbox. While they can be used to study many diseases, they are particularly valuable for rare diseases, small populations, studies involving terminal illnesses, and vaccine trials, in which it is important to find efficient ways to bring effective treatments to market more rapidly. It is imperative, however, that these methodologies be utilized appropriately, which requires careful planning and precise operational execution.
- Published
- 2017
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13. Partnering With Patients to Improve Care: The Value of Patient and Family Advisory Councils.
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Cunningham R and Walton MK
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- Cooperative Behavior, Humans, Quality Improvement, Advisory Committees organization & administration, Nursing Staff, Hospital organization & administration, Patient Satisfaction, Patient-Centered Care organization & administration, Professional-Family Relations, Professional-Patient Relations
- Abstract
Increasingly, healthcare organizations are adopting patient and family advisory councils as a key strategy to create a culture grounded in patient- and family-centered principles and improve the patient experience. In the 1st of a 3-part series, the chief nurse executive and the director of patient- and family-centered care at a Magnet®-designated academic medical center discuss how a stronger patient voice can lead to better care and improved clinical outcomes. The authors examine ways in which the Magnet culture helped drive change and offer tips to establish a successful patient and family advisory council.
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- 2016
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14. Patient-Centered Care and the Mediator's Skills.
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Walton MK
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- Caregivers, Emotions, Humans, Organizational Culture, Patient Participation, Patient Satisfaction, Proxy, Communication, Conflict of Interest, Ethicists standards, Negotiating methods, Patient-Centered Care ethics, Patient-Centered Care methods, Patient-Centered Care standards, Physician-Patient Relations ethics
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Bioethics mediation training offers knowledge and skills valuable for clinical ethics consultants who are engaged in high conflict situations. Furthermore, clinicians with this training can support organizational efforts to create a culture that is centered on the values, needs, and care preferences of patients and their families, rather than on those of the clinician or organization. Patient-centeredness is a hallmark of quality and an essential component for patients' safety. Clinicians with mediation training have the communication skills to address the myriad needs of patients and their loved ones, needs that are challenging to meet in inpatient hospital settings. The author illustrates principles of mediation such as validating patients' emotions, revealing the interests of all stakeholders, and shaping a shared solution to demonstrate how these skills have broad applicability in patient care settings., (Copyright 2015 The Journal of Clinical Ethics. All rights reserved.)
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- 2015
15. Clinical Outcome Assessments: Conceptual Foundation-Report of the ISPOR Clinical Outcomes Assessment - Emerging Good Practices for Outcomes Research Task Force.
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Walton MK, Powers JH 3rd, Hobart J, Patrick D, Marquis P, Vamvakas S, Isaac M, Molsen E, Cano S, and Burke LB
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- Activities of Daily Living, Clinical Trials as Topic classification, Consensus, Emotions, Endpoint Determination classification, Health Services Research classification, Health Status, Humans, Process Assessment, Health Care classification, Recovery of Function, Terminology as Topic, Treatment Outcome, Clinical Trials as Topic standards, Endpoint Determination standards, Health Services Research standards, Process Assessment, Health Care standards
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An outcome assessment, the patient assessment used in an endpoint, is the measuring instrument that provides a rating or score (categorical or continuous) that is intended to represent some aspect of the patient's health status. Outcome assessments are used to define efficacy endpoints when developing a therapy for a disease or condition. Most efficacy endpoints are based on specified clinical assessments of patients. When clinical assessments are used as clinical trial outcomes, they are called clinical outcome assessments (COAs). COAs include any assessment that may be influenced by human choices, judgment, or motivation. COAs must be well-defined and possess adequate measurement properties to demonstrate (directly or indirectly) the benefits of a treatment. In contrast, a biomarker assessment is one that is subject to little, if any, patient motivational or rater judgmental influence. This is the first of two reports by the ISPOR Clinical Outcomes Assessment - Emerging Good Practices for Outcomes Research Task Force. This report provides foundational definitions important for an understanding of COA measurement principles. The foundation provided in this report includes what it means to demonstrate a beneficial effect, how assessments of patients relate to the objective of showing a treatment's benefit, and how these assessments are used in clinical trial endpoints. In addition, this report describes intrinsic attributes of patient assessments and clinical trial factors that can affect the properties of the measurements. These factors should be considered when developing or refining assessments. These considerations will aid investigators designing trials in their choice of using an existing assessment or developing a new outcome assessment. Although the focus of this report is on the development of a new COA to define endpoints in a clinical trial, these principles may be applied more generally. A critical element in appraising or developing a COA is to describe the treatment's intended benefit as an effect on a clearly identified aspect of how a patient feels or functions. This aspect must have importance to the patient and be part of the patient's typical life. This meaningful health aspect can be measured directly or measured indirectly when it is impractical to evaluate it directly or when it is difficult to measure. For indirect measurement, a concept of interest (COI) can be identified. The COI must be related to how a patient feels or functions. Procedures are then developed to measure the COI. The relationship of these measurements with how a patient feels or functions in the intended setting and manner of use of the COA (the context of use) could then be defined. A COA has identifiable attributes or characteristics that affect the measurement properties of the COA when used in endpoints. One of these features is whether judgment can influence the measurement, and if so, whose judgment. This attribute defines four categories of COAs: patient reported outcomes, clinician reported outcomes, observer reported outcomes, and performance outcomes. A full description as well as explanation of other important COA features is included in this report. The information in this report should aid in the development, refinement, and standardization of COAs, and, ultimately, improve their measurement properties., (Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.)
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- 2015
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16. Challenges and opportunities in designing clinical trials for neuromyelitis optica.
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Weinshenker BG, Barron G, Behne JM, Bennett JL, Chin PS, Cree BA, de Seze J, Flor A, Fujihara K, Greenberg B, Higashi S, Holt W, Khan O, Knappertz V, Levy M, Melia AT, Palace J, Smith TJ, Sormani MP, Van Herle K, VanMeter S, Villoslada P, Walton MK, Wasiewski W, Wingerchuk DM, and Yeaman MR
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- Humans, Clinical Trials as Topic standards, Neuromyelitis Optica drug therapy, Research Design standards
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Current management of neuromyelitis optica (NMO) is noncurative and only partially effective. Immunosuppressive or immunomodulatory agents are the mainstays of maintenance treatment. Safer, better-tolerated, and proven effective treatments are needed. The perceived rarity of NMO has impeded clinical trials for this disease. However, a diagnostic biomarker and recognition of a wider spectrum of NMO presentations has expanded the patient population from which study candidates might be recruited. Emerging insights into the pathogenesis of NMO have provided rationale for exploring new therapeutic targets. Academic, pharmaceutical, and regulatory communities are increasingly interested in meeting the unmet needs of patients with NMO. Clinical trials powered to yield unambiguous outcomes and designed to facilitate rapid evaluation of an expanding pipeline of experimental agents are needed. NMO-related disability occurs incrementally as a result of attacks; thus, limiting attack frequency and severity are critical treatment goals. Yet, the severity of NMO and perception that currently available agents are effective pose challenges to study design. We propose strategies for NMO clinical trials to evaluate agents targeting recovery from acute attacks and prevention of relapses, the 2 primary goals of NMO treatment. Aligning the interests of all stakeholders is an essential step to this end., (© 2015 American Academy of Neurology.)
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- 2015
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17. Commonalities and challenges in the development of clinical trial measures in neurology.
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Cedarbaum JM, Stephenson D, Rudick R, Carrillo MC, Stebbins G, Kerr D, Heemskerk J, Galpern WR, Kaufmann P, Cella D, Isaac M, and Walton MK
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- Humans, Clinical Trials as Topic, Neurology methods, Outcome Assessment, Health Care methods
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As neurologists and neuroscientists, we are trained to evaluate disorders of the nervous system by thinking systematically. Clinically, we think in terms of cognition, behavior, motor function, sensation, balance and co-ordination, and autonomic system function. But when we assess symptoms of neurological disorders for the purpose of drug development, we tend to create disease-specific outcome measures, often using a variety of methods to assess the same types of dysfunction in overlapping, related disorders. To begin to explore the potential to simplify and harmonize the assessment of dysfunction across neurological disorders, a symposium, entitled, "Commonalities in the Development of Outcome Measures in Neurology" was held at the 16th annual meeting of the American Society for Experimental NeuroTherapeutics (ASENT), in February 2014. This paper summarizes the presentations at the symposium. The authors hope that readers will begin to view Clinical Outcome Assessment (COA) development in a new light. We hope that in presenting this material, we will stimulate discussions and collaborations across disease areas to develop common concepts of neurological COA development and construction.
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- 2015
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18. Erratum to: Commonalities and Challenges in the Development of Clinical Trial Measures in Neurology.
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Cedarbaum JM, Stephenson D, Rudick R, Carrillo MC, Stebbins G, Kerr D, Heemskerk J, Galpern WR, Kaufmann P, Cella D, Isaac M, and Walton MK
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- 2015
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19. Mandate for care.
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Barnsteiner J, Disch J, and Walton MK
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MUCH HAS been written on the need to move to a more patient- and family-centred system of healthcare delivery. Recognised steps that nursing staff can take to design patient-centred care delivery models include, for example, unrestricted visiting for family members, hourly rounding and having open medical record policies.
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- 2014
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20. Person- and family-centred care.
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Walton MK
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- Family Nursing, Humans, Nurse's Role, Patient-Centered Care
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- 2014
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21. Evaluating cognitive outcome measures for MS clinical trials: what is a clinically meaningful change?
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Benedict RH and Walton MK
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- Clinical Trials as Topic, Humans, Neuropsychological Tests, Multiple Sclerosis therapy, Outcome Assessment, Health Care standards, Psychometrics methods
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Brief cognitive assessments are increasingly emphasized in MS treatment studies and clinical care. While much is known about the reliability of several widely-used neuropsychological tests, interpretation of the changes in individual patients is inadequate. The FDA offers guidance on the issue, as related to patient-reported outcomes. Unfortunately, cognitive ability is only weakly correlated with the frequency and severity of self-reported cognitive problems. In this review, we critically examined the psychometrics of neuropsychological testing in MS, emphasizing statistical and anchor-based approaches to interpreting clinically meaningful change. We suggest that there are two paths forward that should be currently pursued. First, to employ co-primary outcomes, including a brief cognitive test and a clinician or observer's impression on a scale of change, where successful treatment would require showing significant improvement in both measures. Secondly, to work toward showing that when reliable brief cognitive tests are employed, increments of statistically-relevant change would correlate with changes in clinically-relevant anchors (such as vocational disability or clinical relapses with cognitive impairment). The latter goal will allow a more parsimonious and scientifically efficient approach of utilizing only the brief cognitive test as a primary outcome. While some progress has been made in this direction, more research is needed. We are of the opinion that data from both the statistical and clinically meaningful approaches will be necessary to develop valid definitions of meaningful change on cognitive outcome measures, and that it would be best to pursue research using tests that already have well-established reliability and validity.
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- 2012
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22. Supporting family caregivers: communicating with family caregivers.
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Walton MK
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- Attitude to Health, Humans, Narration, Nurse's Role, Nurse-Patient Relations, Patient Discharge, Quality of Health Care, Caregivers ethics, Caregivers psychology, Communication, Professional-Family Relations ethics
- Abstract
Nurses can foster partnerships with patients and families during acute care hospitalizations.
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- 2011
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23. Qualifying biomarkers for use in drug development: a US Food and Drug Administration overview.
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Woodcock J, Buckman S, Goodsaid F, Walton MK, and Zineh I
- Abstract
Despite huge investments, there are still difficulties in the development of novel therapies. This has led to a growing interest in the use of new tools, such as biomarkers, that can help overcome development hurdles while providing increased certainty about drug safety and efficacy. Until recently, no formal process has existed for qualifying biomarkers for regulatory decision making. The FDA's Center for Drug Evaluation and Research (CDER) has initiated such a process, which has led to the recent qualification of two biomarker sets for use in regulatory decisions. This article provides the reader with an overview of the CDER Biomarker Qualification Process and is shaped by the recent regulatory developments in biomarker qualification and the consideration of frequently asked questions in the area. The Biomarker Qualification Process is intended to be a mission-critical, value-added CDER program. The success of this effort will depend on the willingness of pharmaceutical and diagnostic companies, consortia, the FDA and other regulatory agencies to continue to work together, motivated by the benefits that can accrue to public health through the increasing availability of qualified biomarkers for use in drug development.
- Published
- 2011
- Full Text
- View/download PDF
24. Translational biomarkers: from preclinical to clinical a report of 2009 AAPS/ACCP Biomarker Workshop.
- Author
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Bai JP, Bell R, Buckman S, Burckart GJ, Eichler HG, Fang KC, Goodsaid FM, Jusko WJ, Lesko LL, Meibohm B, Patterson SD, Puig O, Smerage JB, Snider BJ, Wagner JA, Wang J, Walton MK, and Weiner R
- Subjects
- Animals, Clinical Trials as Topic methods, Drug Evaluation, Preclinical methods, Humans, International Cooperation, Biomarkers metabolism, Drug Design, Drug Industry methods
- Abstract
There have been some successes in qualifying biomarkers and applying them to drug development and clinical treatment of various diseases. A recent success is illustrated by a collaborative effort among the US Food and Drug Administration, the European Medicines Agency, and the pharmaceutical industry to provide a set of seven preclinical kidney toxicity biomarkers for drug development. Other successes include, but are not limited to, clinical biomarkers for cancer treatment and clinical management of heart transplant patients. The value of fully qualified surrogate endpoints in facilitating successful drug development is undisputed, especially for diseases in which the traditional clinical outcome can only be assessed in large, multi-year trials. Emerging biomarkers, including chemical genomic or imaging biomarkers, and measurement of circulating tumor cells hold great promise for early diagnosis of disease and as prognostic tests for managing treatment of chronic diseases such as osteoarthritis, Alzheimer disease, cardiovascular disease, and cancer. To advance the success of treating and managing these diseases, efforts are needed to establish the temporal relationship between changes in inflammatory or imaging biomarkers with the progression of the chronic disease, and in the case of cancer, between the extent of circulating cancer cells and tumor progression or remission.
- Published
- 2011
- Full Text
- View/download PDF
25. Promoting evidence-based practice and translational research.
- Author
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Barnsteiner JH, Reeder VC, Palma WH, Preston AM, and Walton MK
- Subjects
- Clinical Governance organization & administration, Education, Nursing, Continuing organization & administration, Fellowships and Scholarships organization & administration, Hospitals, University organization & administration, Humans, Information Dissemination, Interinstitutional Relations, Internet organization & administration, Mentors, Models, Nursing, Philadelphia, Professional Staff Committees organization & administration, Research Support as Topic organization & administration, Schools, Nursing organization & administration, Teaching Rounds organization & administration, Diffusion of Innovation, Evidence-Based Practice education, Evidence-Based Practice organization & administration, Nursing Research education, Nursing Research organization & administration, Nursing Staff, Hospital education, Nursing Staff, Hospital organization & administration, Translational Research, Biomedical education, Translational Research, Biomedical organization & administration
- Abstract
Evidence-based practice (EBP) is an evolutionary step in the nursing model of excellence in professional practice at the Hospital of the University of Pennsylvania. A healthcare culture focused on excellence and world-class patient care requires that nursing research and EBP are integrated into the professional practice model and nursing care delivery. To achieve this, it requires the development of staff expertise, time allocation for staff to participate in scholarly activities, resources that support EBP and research, and expert consultants in EBP and nursing translational research. This article describes the systems and structures in place to provide staff with resources in order to translate research and deliver EBP and the multiple initiatives in disseminating evidence to the point of care.
- Published
- 2010
- Full Text
- View/download PDF
26. Addressing and advancing the problem of missing data.
- Author
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Walton MK
- Subjects
- Humans, Research Design, Clinical Trials as Topic statistics & numerical data, Data Collection, Data Interpretation, Statistical
- Abstract
Missing data can pose substantial risk of reaching incorrect conclusions from clinical studies. Imputation for the missing values is common, but can supply only an approximate result desired to be "close enough" to the intended true result. Prevention optimally addresses the issue. Knowledge of the effective techniques to minimize the problem, likely to vary with clinical setting, is presently inadequate. Formal evaluation of preventative methods should be encouraged and lead to publication of the assessments. Designers of clinical trials should also plan for study analysis where missing values occur. Simple imputation methods have been used and may be sufficient in some settings, but have potential to introduce bias and inaccuracy into the statistical analysis. More complex methods such as multiple imputation potentially offer reduced risk of bias. Multiple imputation also offers the potential for study designers to include some auxiliary outcome assessments that may substantially improve the quality of the imputation with limited added burden to the study. In all cases, sensitivity analyses examining the importance of the specific preferred method as compared to methods with different underlying assumptions is essential to assessing how adequately the missing data issue has been addressed.
- Published
- 2009
- Full Text
- View/download PDF
27. Assessing disability progression with the Multiple Sclerosis Functional Composite.
- Author
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Rudick RA, Polman CH, Cohen JA, Walton MK, Miller AE, Confavreux C, Lublin FD, Hutchinson M, O'Connor PW, Schwid SR, Balcer LJ, Lynn F, Panzara MA, and Sandrock AW
- Subjects
- Adult, Antibodies, Monoclonal therapeutic use, Antibodies, Monoclonal, Humanized, Cognition, Disease Progression, Drug Therapy, Combination, Female, Humans, Immunologic Factors therapeutic use, Interferon beta-1a, Interferon-beta therapeutic use, Kaplan-Meier Estimate, Male, Middle Aged, Multiple Sclerosis, Relapsing-Remitting drug therapy, Multiple Sclerosis, Relapsing-Remitting physiopathology, Multiple Sclerosis, Relapsing-Remitting psychology, Natalizumab, Predictive Value of Tests, Proportional Hazards Models, Randomized Controlled Trials as Topic, Recurrence, Sensitivity and Specificity, Time Factors, Treatment Outcome, Upper Extremity physiopathology, Walking, Disability Evaluation, Health Status Indicators, Multiple Sclerosis, Relapsing-Remitting diagnosis
- Abstract
Background: The initial Multiple Sclerosis Functional Composite (MSFC) proposal was a three-part composite of quantitative measures of ambulation, upper extremity function, and cognitive function expressed as a single composite Z-score. However, the clinical meaning of an MSFC Z-score change is not obvious. This study instead used MSFC component data to define a patient-specific disease progression event., Objective: Evaluate a new method for analyzing disability progression using the MSFC., Methods: MSFC progression was defined as worsening from baseline on scores of at least one MSFC component by 20% (MSFC Progression-20) or 15% (MSFC Progression-15), sustained for >or=3 months. Progression rates were determined using data from natalizumab clinical studies (Natalizumab Safety and Efficacy in Relapsing Remitting Multiple Sclerosis [AFFIRM] and Safety and Efficacy of Natalizumab in Combination With Interferon Beta-1a in Patients With Relapsing Remitting Multiple Sclerosis [SENTINEL]). Correlations between MSFC progression and other clinical measures were determined, as was sensitivity to treatment effects., Results: Substantial numbers of patients met MSFC progression criteria, with MSFC Progression-15 being more sensitive than MSFC Progression-20, at both 1 and 2 years. MSFC Progression-20 and MSFC Progression-15 were related significantly to Expanded Disability Status Scale (EDSS) score change, relapse rate, and the SF-36 Physical Component Summary (PCS) score change. MSFC Progression-20 and MSFC Progression-15 at 1 year were predictive of EDSS progression at 2 years. Both MSFC progression end points demonstrated treatment effects in AFFIRM, and results were replicated in SENTINEL., Conclusion: MSFC Progression-20 and MSFC Progression-15 are sensitive measures of disability progression; correlate with EDSS, relapse rates, and SF-36 PCS; and are capable of demonstrating therapeutic effects in randomized, controlled clinical studies.
- Published
- 2009
- Full Text
- View/download PDF
28. Botulinum toxin type A injections: adverse events reported to the US Food and Drug Administration in therapeutic and cosmetic cases.
- Author
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Coté TR, Mohan AK, Polder JA, Walton MK, and Braun MM
- Subjects
- Adult, Aged, Female, Humans, Male, Middle Aged, Product Surveillance, Postmarketing, Retrospective Studies, United States, United States Food and Drug Administration, Adverse Drug Reaction Reporting Systems, Botulinum Toxins, Type A adverse effects, Neuromuscular Agents adverse effects
- Abstract
Background: Botulinum toxin type A (BTA) (Botox) received Food and Drug Administration (FDA) approval for therapeutic treatment of strabismus and blepharospasm in 1989, cervical dystonia in 2000, and cosmetic treatment of glabellar wrinkles (Botox Cosmetic) in 2002. In 2002 alone there were approximately 1.1 to 1.6 million patients using cosmetic BTA. Our objective was to review adverse event (AE) reporting to the FDA after BTA administration., Methods: We reviewed all (therapeutic and cosmetic use) serious (per FDA regulations) AEs reported to the FDA for the 13.5 years since licensure of the product (December 1989-May 2003) and nonserious AEs reported from December 2001 to November 2002. AEs are reported to the FDA through the MedWatch system., Results: We reviewed 1437 AE reports; 406 followed therapeutic use of BTA (217 serious and 189 nonserious) and 1031 followed cosmetic use (36 serious and 995 nonserious). Reported AEs occurred predominantly in female patients, with a median age of 50 years. In the year December 2001 to November 2002, when both serious and nonserious reports were evaluated, the proportion of reports classified as serious was 33-fold higher for therapeutic than for cosmetic cases. The 217 serious AEs reported in therapeutic cases involved a wide spectrum of events and included all 28 reported deaths. Among cosmetic users, no deaths were reported and, of the 36 serious AEs, 30 were included as possible complications in the FDA-approved label. The remaining 6 serious AEs did not display a pattern suggesting a common causal relationship to BTA. Among the 995 cosmetic cases reported to have nonserious AEs, most commonly noted were lack of effect (623, 63%), injection site reaction (190, 19%), and ptosis (111, 11%)., Conclusions: Serious AEs were more likely to be reported for therapeutic than for cosmetic use, which may be related to higher doses, complicated underlying diseases, or both. Among cosmetic cases, few serious AEs were reported, and these were predominantly events that were previously recognized in clinical trials of BTA for the labeled use. This study is limited primarily by the incomplete nature of AE reporting by clinicians. Numerous departures from FDA-approved recommendations for drug dose, dilution, handling, site of injection, and storage were noted in these AE reports.
- Published
- 2005
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- View/download PDF
29. Milk depots, yarn trusses, and pediatric nurses.
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Barnsteiner JH and Walton MK
- Subjects
- Child, History, 19th Century, History, 20th Century, Humans, Infant, Infant, Newborn, United States, Hospitals, Pediatric history, Pediatric Nursing history
- Published
- 2005
30. A look back: nursing care of typhoid fever: the pivotal role of nurses at the Children's Hospital of Philadelphia between 1895 and 1910: how the past informs the present.
- Author
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Walton MK and Connolly CA
- Subjects
- Adolescent, Child, History, 19th Century, History, 20th Century, Hospitals, Pediatric history, Humans, Philadelphia, Typhoid Fever nursing, History of Nursing, Typhoid Fever history
- Published
- 2005
- Full Text
- View/download PDF
31. Use of surrogate markers.
- Author
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Walton MK
- Subjects
- Amyotrophic Lateral Sclerosis physiopathology, Biomarkers analysis, Electric Stimulation methods, Humans, Muscle, Skeletal physiopathology, Predictive Value of Tests, Reproducibility of Results, Retrospective Studies, Time Factors, Amyotrophic Lateral Sclerosis diagnosis, Evoked Potentials, Motor physiology
- Published
- 2004
- Full Text
- View/download PDF
32. Advocacy and leadership when parental rights and child welfare collide: the role of the advanced practice nurse.
- Author
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Walton MK
- Subjects
- Adult, Child, Chronic Disease, Cystic Fibrosis nursing, Female, Humans, Infant, Newborn, Intellectual Disability nursing, United States, Child Advocacy legislation & jurisprudence, Child Custody legislation & jurisprudence, Leadership, Nurse Practitioners, Nurse's Role, Parenting
- Abstract
This article describes the experience of an advanced practice nurse in a challenging clinical situation. A mother with mental illness and mental retardation seeks to retain parental rights and care for her newborn with cystic fibrosis. The nurse provides leadership to the hospital team and serves as an advocate throughout legal proceedings. A systematic, nonjudgmental, and empathic approach to gathering information, working with the family, welfare, and legal representatives is described. Enacting a complex and court-mandated homecare education regimen to the disabled mother is discussed. Preparation to testify in a termination of parental rights proceeding is outlined and a summary description of the testimony provided., (Copyright 2002, Elsevier Science (USA).)
- Published
- 2002
- Full Text
- View/download PDF
33. Endpoint considerations for clinical trials.
- Author
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Walton MK
- Subjects
- Humans, Reproducibility of Results, Research Design, Terminology as Topic, Treatment Outcome, Amyotrophic Lateral Sclerosis drug therapy, Clinical Trials as Topic, Endpoint Determination
- Published
- 2002
- Full Text
- View/download PDF
34. Distribution of GABA(C)-like responses among acutely dissociated rat retinal neurons.
- Author
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Nelson R, Schaffner AE, Li YX, and Walton MK
- Subjects
- Animals, Barbiturates metabolism, Fluorescent Dyes metabolism, GABA Agonists pharmacology, GABA Antagonists pharmacology, Interneurons metabolism, Isoxazoles metabolism, Neurons drug effects, Rats, Rats, Sprague-Dawley, Receptors, GABA metabolism, Retina drug effects, Neurons metabolism, Retina metabolism, gamma-Aminobutyric Acid metabolism
- Abstract
GABAergic responses of acutely dissociated rat retinal neurons, including both bipolar cells (BCs) and other, morphologically round cells (RCs), were assayed with the fluorescent (FL), voltage-sensitive probe oxonol DiBaC4(5). Using intensified video microscopy and simultaneous recording, GABA responses were identified in one-third of cells in a typical microscope field; of these 85% hyperpolarized (0.05-0.3 log unit FL decreases) while the remainder depolarized (0.05-0.2 log unit FL increases). GABA-sensitive cells were also TACA-sensitive (trans-4-Aminocrotonic acid), and these ligands appeared interchangeable in ability to evoke responses. In RCs, an asymmetric co-responsive pattern was observed between GABA- and muscimol-evoked events. Muscimol-sensitive RCs responded well to GABA, but not all GABA-sensitive RCs responded to muscimol. In GABA-sensitive BCs, muscimol responses were typically weak or absent. Few BCs or RCs responded to CACA (cis-4-Aminocrotonic acid). Bicuculline-resistant GABA responses occurred in approximately 80% of GABA-responsive RCs and BCs. Both bicuculline-sensitive (GABA(A)-like) and bicuculline-insensitive (GABAc-like) responses were resistant to picrotoxin. Although a small minority of GABA-sensitive cells hyperpolarized in response to R(+)baclofen, bicuculline-insensitive responses were not antagonized by 2-hydroxysaclofen, and were abolished in low [Cl-]o. Results suggested (1) that bicuculline-insensitive, Cl(-)-dependent, GABAc-like responses were broadly distributed and predominant among dissociated rat retinal neurons; (2) that muscimol was a particularly weak agonist for rat retinal BCs; and (3) that oxonol was a sensitive probe for retinal GABA responses.
- Published
- 1999
- Full Text
- View/download PDF
35. Astrocytes regulate developmental changes in the chloride ion gradient of embryonic rat ventral spinal cord neurons in culture.
- Author
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Li YX, Schaffner AE, Walton MK, and Barker JL
- Subjects
- Animals, Bicuculline pharmacology, Calcium metabolism, Calcium Channel Blockers pharmacology, Cells, Cultured, Chloride Channels physiology, Chlorides pharmacokinetics, Culture Media, Conditioned pharmacology, GABA Agonists pharmacology, GABA Antagonists pharmacology, Membrane Potentials drug effects, Microscopy, Video, Muscimol pharmacology, Neurons cytology, Neurons drug effects, Nifedipine pharmacology, Patch-Clamp Techniques, Rats, Receptors, GABA-A physiology, Spinal Cord chemistry, Time Factors, gamma-Aminobutyric Acid physiology, Astrocytes physiology, Chlorides metabolism, Neurons chemistry, Spinal Cord cytology, Spinal Cord embryology
- Abstract
1. Embryonic rat ventral spinal cord neurons were dissociated at day 15 and grown on: (i) poly-D-lysine (PDL); (ii) a confluent monolayer of type I astrocytes; or (iii) PDL in astrocyte-conditioned medium (ACM) to examine the influence of astroglia on the regulation of GABAA receptor/Cl- channel properties. 2. Potentiometric oxonol dye recordings of intact cells indicated that embryonic neurons were uniformly depolarized by muscimol. The depolarizing effects disappeared in cells dissociated during the early postnatal period and recovered in culture for 24 h. Similar recordings using the calcium-imaging dye fura-2 AM revealed that GABA or muscimol triggered a sustained rise in cytosolic Ca2+ (Ca2+c ) in embryonic neurons that was dependent on extracellular Ca2+, blocked by bicuculline and nifedipine and sensitive to changes in extracellular chloride. The incidence and amplitude of the Ca2+ response decreased with time in vitro and was accelerated in neurons cultured on astrocytes compared with those on PDL. 3. Perforated patch-clamp recordings revealed that GABA depolarized neurons in a Cl--dependent and bicuculline-sensitive manner. Both the resting membrane potential and the GABA equilibrium potential became more hyperpolarized with time in vitro. 4. Astrocytes and ACM accelerated the transformation of GABAergic potential responses from depolarizing to hyperpolarizing. The change occurred over the first 4 days in co-culture or in ACM but took more than 2 weeks in neurons cultured on PDL alone. 5. The intrinsic, elementary properties of GABAA receptor/Cl- channels including open time and unitary conductance changed independently of the presence of astrocytes or ACM. Mean open time of the dominant kinetic component decreased and conductance increased with time in vitro. 6. In sum, astrocytes accelerate the developmental change in the Cl- ion gradient extrinsic to GABAA receptor/Cl- channels, which is critical for triggering Ca2+ entry, without influencing parallel changes in the intrinsic properties of the channels.
- Published
- 1998
- Full Text
- View/download PDF
36. A collaborative practice model for the clinical nurse specialist.
- Author
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Walton MK, Jakobowski DS, and Barnsteiner JH
- Subjects
- Hospitals, Pediatric, Humans, Medical Staff, Hospital, Nurse Administrators, Nursing Research, Patient Education as Topic, Philadelphia, Professional-Family Relations, Interprofessional Relations, Models, Nursing, Nurse Clinicians
- Abstract
This article describes a model of advanced nursing practice, jointly funded through nursing and medicine. The model is based on a matrix reporting structure with the clinical nurse specialist reporting to both a physician and a director of nursing. The authors discuss how the various role components are enacted and the benefits of the model to the specialist, institution, physicians, staff, and patients and their families.
- Published
- 1993
- Full Text
- View/download PDF
37. The conducted action potential. Models and comparison to experiments.
- Author
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Walton MK and Fozzard HA
- Subjects
- Animals, Mathematics, Membrane Potentials, Models, Neurological, Neurons physiology, Action Potentials, Models, Biological
- Abstract
Propagation of the action potential is a complex process, and the relationships among the various factors involved in conduction have not been clear. We use three mathematical models of uniform conduction in a cable to clarify some of these relationships. One model is newly derived here, and two have been previously derived by Hunter et al. (1975, Prog. Biophys. Mol. Biol., 30:99-144). These models were able to simulate individual experimental action potential upstrokes previously obtained (Walton and Fozzard, 1983, Biophys. J., 44:1-8). The models were then utilized to provide relationships between measures of conduction. Among these were that maximal upstroke velocity (Vmax) is directly proportional to peak inward ionic current normalized by capacitance that is filled during the upstroke (I/Cf), and that conduction velocity was directly related to the square root of either Vmax or I/Cf. These relationships were shown to be model independent and to predict the experimental results, thus providing validated quantitative relationships that were not discernible through use of experimental data alone. The concept of safety factor was considered and a parameter was proposed that may be related to safety factor.
- Published
- 1983
- Full Text
- View/download PDF
38. Experimental study of the conducted action potential in cardiac Purkinje strands.
- Author
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Walton MK and Fozzard HA
- Subjects
- Animals, Electric Conductivity, Electric Stimulation, Microelectrodes, Models, Neurological, Purkinje Fibers drug effects, Sheep, Sodium pharmacology, Heart Conduction System physiology, Purkinje Fibers physiology
- Abstract
Conduction velocity is a complex physiological process that integrates the active and passive properties of the excitable cell. The relations between these properties in determining the conduction velocity are not intuitively obvious, and models have been used frequently to illustrate important relationships. To study the relationships of important parameters and to evaluate commonly used models, we changed conduction velocity experimentally in sheep cardiac Purkinje strands by reducing extracellular Na systematically. Cable analyses were also performed to obtain passive membrane and cable properties. Resting membrane resistance and capacitance did not change, nor did core resistance. Active properties measured in addition to conduction velocity included maximal upstroke velocity, action potential height, time constant of the foot, peak inward current, and upstroke power. With reduction in extracellular Na, all of these parameters of the action potential changed nonlinearly and not in direct proportion to the change in conduction velocity. The only simple relation found was a linear relationship between maximal upstroke velocity and peak inward current, normalized by the capacity of the foot. Models based on the cable equation and the wave equation offer a basis for quantitative analysis of conduction, and these data can be used to test the models.
- Published
- 1983
- Full Text
- View/download PDF
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