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Aim: Regulatory and health technology assessment (HTA) agencies have increasingly published frameworks, guidelines, and recommendations for the use of real-world evidence (RWE) in healthcare decision-making. Variations in the scope and content of these documents, with updates running in parallel, may create challenges for their implementation especially during the market authorization and reimbursement phases of a medicine's life cycle. This environmental scan aimed to comprehensively identify and summarize the guidance documents for RWE developed by most well-established regulatory and reimbursement agencies, as well as other organizations focused on healthcare decision-making, and present their similarities and differences.  Methods: RWE guidance documents, including white papers from regulatory and HTA agencies, were reviewed in March 2024. Data on scope and recommendations from each body were extracted by two reviewers and similarities and differences were summarized across four topics: study planning, choosing fit-for-purpose data, study conduct, and reporting. Post-authorization or non-pharmacological guidance was excluded. Results: Forty-six documents were identified across multiple agencies; US FDA produced the most RWE-related guidance. All agencies addressed specific and often similar methodological issues related to study design, data fitness-for-purpose, reliability, and reproducibility, although inconsistency in terminologies on these topics was noted. Two HTA bodies (National Institute for Health and Care Excellence [NICE] and Canada's Drug Agency) each centralized all related RWE guidance under a unified framework. RWE quality tools and checklists were not consistently named and some differences in preferences were noted. European Medicines Agency, NICE, Haute Autorité de Santé, and the Institute for Quality and Efficiency in Health Care included specific recommendations on the use of analytical approaches to address RWE complexities and increase trust in its findings. Conclusion: Similarities in agencies' expectations on RWE studies design, quality elements, and reporting will facilitate evidence generation strategy and activities for manufacturers facing multiple, including global, regulatory and reimbursement submissions and re-submissions. A strong preference by decision-making bodies for local real-world data generation may hinder opportunities for data sharing and outputs from international federated data networks. Closer collaboration between decision-making agencies towards a harmonized RWE roadmap, which can be centrally preserved in a living mode, will provide manufacturers and researchers clarity on minimum acceptance requirements and expectations, especially as novel methodologies for RWE generation are rapidly emerging.

Background and Objective: Multiple myeloma is a rare incurable hematological cancer in which most patients relapse or become refractory to treatment. This systematic literature review aimed to critically review the existing economic models used in economic evaluations of systemic treatments for relapsed/refractory multiple myeloma and to summarize how the models addressed differences in the line of therapy and exposure to prior treatment., Methods: Following a pre-approved protocol, literature searches were conducted on 17 February, 2023, in relevant databases for models published since 2014. Additionally, key health technology assessment agency websites were manually searched for models published as part of submission dossiers since 2018. Reported information related to model conceptualization, structure, uncertainty, validation, and transparency were extracted into a pre-defined extraction sheet., Results: In total, 49 models assessing a wide range of interventions across multiple lines of therapy were included. Only five models specific to heavily pre-treated patients and/or those who were refractory to multiple treatment classes were identified. Most models followed a conventional simple methodology, such as partitioned survival (n = 28) or Markov models (n = 9). All included models evaluated specific interventions rather than the whole treatment sequence. Where subsequent therapies were included in the model, these were generally only considered from a cost and resource use perspective. The models generally used overall and progression-free survival as model inputs, although data were often immature. Sensitivity analyses were frequently reported (n = 41) whereas validation was only considered in less than half (n = 19) of the models., Conclusions: Published economic models in relapsed/refractory multiple myeloma rarely followed an individual patient approach, mainly owing to the higher need for complex data assumptions compared with simpler modeling approaches. As many patients experience disease progression on multiple treatment lines, there is a growing need for modeling complex treatment strategies, leading to more sophisticated approaches in the future. Maintaining transparency, high reporting standards, and thorough analyses of uncertainty are crucial to support these advancements., (© 2024. The Author(s).)

Cost-effectiveness analyses (CEA) are important in healthcare decision-making and resource allocation; however, expanding the scope of CEAs beyond the traditional clinicoeconomic concepts to also include value elements such as health equity has attracted much interest in recent years. This umbrella review aimed to synthesize evidence on how equity concepts have been considered in modified types of CEAs. Publicly available articles in MEDLINE were searched on January 25, 2024, to identify systematic reviews (SLRs) published in English since 2013 that incorporate health equity considerations in CEAs. Title/abstract, full-text article screening and data extraction were conducted by a single reviewer and validated by a second reviewer. Results were qualitatively synthesized to identify common themes. Eight SLRs were included. Distributional CEAs (DCEA), equity-based weighting, extended CEA (ECEA), mathematical programming and multi-criteria decision analysis (MCDA) were the most discussed approaches. A lack of consensus on the best approach for incorporating health equity into CEAs was highlighted, as these approaches are not currently consistently used in decision-making. Important limitations included scarcity of robust data to inform health equity indices, bias associated with commonly used health outcome metrics and the challenge of accounting for additional contextual factors such as fairness and opportunity costs. Proposals to expand CEAs to address equity issues come with challenges due to data unavailability, methods complexity, and decision-makers unfamiliarity with these approaches. Our review indicates that extended and distributional CEAs can support decision-making by capturing the impact of inequity on the clinical and cost-effectiveness assessment of treatments, although future modeling should account for additional contextual factors such as fairness and opportunity costs. Recommendations for actions moving forward include standardization of data collection for outcomes related to equity and familiarity with methodologies to account for the complexities of integrating health equity considerations in CEAs., Competing Interests: JMM, AR and GS are employees of Cytel, Inc. IOS is an employee of Takeda Pharmaceuticals, Inc. The authors declare no other competing interests in this work., (© 2024 Muir et al.)

We report on an experimental observation of the streaking of betatron x rays in a curved laser wakefield accelerator. The streaking of the betatron x rays was realized by launching a laser pulse into a plasma with a transverse density gradient. By controlling the plasma density and the density gradient, we realized the steering of the laser driver, electron beam, and betatron x rays simultaneously. Moreover, we observed an energy-angle correlation of the streaked betatron x rays and utilized it in diagnosing the electron acceleration process in a single-shot mode. Our work could also find applications in advanced control of laser beam and particle propagation. More importantly, the angular streaked betatron x ray has an intrinsic spatiotemporal correlation, which makes it a promising tool for single-shot pump-probe applications.

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers P<250  TW and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies E&#95;{max}>2.5  GeV, in fields exceeding 500  GV m^{-1}, with more than 80 pC of charge at energies E>1  GeV. Three-dimensional particle-in-cell simulations show that using an oversized spot delays injection, avoiding beam loss as the wakefield undergoes length oscillation. This enables injected electrons to remain in the regions of highest accelerating fields and leads to a doubling of energy gain as compared to results from using half the focal length with the same laser.

Background: Health disparities, starkly exposed and exacerbated by coronavirus disease 2019, pose a significant challenge to healthcare system access and health outcomes. Integrating health inequalities into health technology assessment calls for robust analytical methodologies utilizing disaggregated data to investigate and quantify the scope of these disparities. However, a comprehensive summary of population datasets that can be used for this purpose is lacking. The objective of this review was to identify publicly accessible health inequalities data repositories that are potential resources for healthcare decision-making and future health technology assessment submissions., Methods: An environmental scan was conducted in June of 2023 of six international organizations (World Health Organization, Organisation for Economic Co-operation and Development, Eurostat, United Nations Inter-agency Group for Child Mortality Estimation, the United Nations Sustainable Development Goals, and World Bank) and 38 Organisation for Economic Co-operation and Development countries. The official websites of 42 jurisdictions, excluding non-English websites and those lacking English translations, were reviewed. Screening and data extraction were performed by two reviewers for each data repository, including health indicators, determinants of health, and health inequality metrics. The results were narratively synthesized., Results: The search identified only a limited number of country-level health inequalities data repositories. The World Health Organization Health Inequality Data Repository emerged as the most comprehensive source of health inequality data. Some country-level data repositories, such as Canada's Health Inequality Data Tool and England's Health Inequality Dashboard, offered rich local insights into determinants of health and numerous health status indicators, including mortality. Data repositories predominantly focused on determinants of health such as age, sex, social deprivation, and geography., Conclusion: Interactive interfaces featuring data exploration and visualization options across diverse patient populations can serve as valuable tools to address health disparities. The data they provide may help inform complex analytical methodologies that integrate health inequality considerations into healthcare decision-making. This may include assessing the feasibility of transporting health inequality data across borders., (© 2024. The Author(s).)

Purpose: This study aimed to demonstrate for the first time the possibility of irradiating biological cells with gray (Gy)-scale doses delivered over single bursts of picosecond-scale electron beams, resulting in unprecedented dose rates of 10 10 to 10 11 Gy/s., Methods and Materials: Cancer stem cells and human skin fibroblasts were irradiated with MeV-scale electron beams from a laser-driven source. Doses up to 3 Gy per pulse with a high spatial uniformity (coefficient of variance, 3%-6%) and within a timescale range of 10 to 20 picoseconds were delivered. Doses were characterized during irradiation and were found to be in agreement with Monte Carlo simulations. Cell survival and DNA double-strand break repair dynamics were studied for both cell lines using clonogenic assay and 53BP1 foci formation. The results were compared with reference x-rays at a dose rate of 0.49 Gy/min., Results: Results from clonogenic assays of both cell lines up to 3 Gy were well fitted by a linear quadratic model with α = (0.68 ± 0.08) Gy -1 and β = (0.01 ± 0.01) Gy -2 for human skin fibroblasts and α = (0.51 ± 0.14) Gy -1 and β = (0.01 ± 0.01) Gy -2 for cancer stem cells. Compared with irradiation at 0.49 Gy/min, our experimental results indicate no statistically significant difference in cell survival rate for doses up to 3 Gy despite a significant increase in the α parameter, which may reflect more complex damage. Foci measurements showed no significant difference between irradiation at 10 11 Gy/s and at 0.49 Gy/min., Conclusions: This study demonstrates the possibility of performing radiobiological studies with picosecond-scale laser-generated electron beams at ultrahigh dose rates of 10 10 to10 11 Gy/s. Preliminary results indicate, within statistical uncertainties, a significant increase of the α parameter, a possible indication of more complex damage induced by a higher density of ionizing tracks., (Crown Copyright © 2023. Published by Elsevier Inc. All rights reserved.)

The rapid progress that plasma wakefield accelerators are experiencing is now posing the question as to whether they could be included in the design of the next generation of high-energy electron-positron colliders. However, the typical structure of the accelerating wakefields presents challenging complications for positron acceleration. Despite seminal proof-of-principle experiments and theoretical proposals, experimental research in plasma-based acceleration of positrons is currently limited by the scarcity of positron beams suitable to seed a plasma accelerator. Here, we report on the first experimental demonstration of a laser-driven source of ultra-relativistic positrons with sufficient spectral and spatial quality to be injected in a plasma accelerator. Our results indicate, in agreement with numerical simulations, selection and transport of positron beamlets containing N e + ≥ 10 5 positrons in a 5% bandwidth around 600 MeV, with femtosecond-scale duration and micron-scale normalised emittance. Particle-in-cell simulations show that positron beams of this kind can be guided and accelerated in a laser-driven plasma accelerator, with favourable scalings to further increase overall charge and energy using PW-scale lasers. The results presented here demonstrate the possibility of performing experimental studies of positron acceleration in a laser-driven wakefield accelerator., (© 2024. The Author(s).)

There is an urgent need for expedited approval and access for new health technologies targeting rare and very rare diseases, some of which are associated with high unmet treatment needs. Once a new technology achieves regulatory approval, the technology needs to be assessed by health technology assessment (HTA) bodies to inform coverage and reimbursement decisions. This assessment quantitatively examines the clinical effectiveness, safety and/or economic impact of the new technology relative to standard of care (SoC) in a specific market. However, in rare and very rare diseases, the patient populations are small and there is often no established treatment pathway available to define 'SoC'. In these situations, several challenges arise to assess the added benefit of a new technology - both clinically and economically - due to lack of established SoC to guide an appropriate comparator selection. These challenges include: How should 'SoC' be defined and characterized in HTA submissions for new technologies aiming to establish new treatment standards? What is usual care without an established clinical pathway? How should the evidence for the comparator 'SoC' (i.e., usual care) arm be collected in situations with low patient representation and, sometimes, limited disease-specific clinical knowledge in certain geographies? This commentary outlines the evidence generation challenges in designing clinical comparative effectiveness for a new technology when there is a lack of established SoC. The commentary also proposes considerations to facilitate the reliable integration of real-world evidence into HTA and decision-making based on the collective experience of the authors.

Background: The drive to expedite patient access for diseases with high unmet treatment needs has come with an increasing use of single-arm trials (SATs), especially in oncology. However, the lack of control arms in such trials creates challenges to assess and demonstrate comparative efficacy. External control (EC) arms can be used to bridge this gap, with various types of sources available to obtain relevant data. Objective: To examine the source of ECs in single-arm oncology health technology assessment (HTA) submissions to the National Institute for Health and Care Excellence (NICE) and the Pharmaceutical Benefits Advisory Committee (PBAC) and how this selection was justified by manufacturers and assessed by the respective HTA body. Methods: Single-arm oncology HTA submission reports published by NICE (England) and PBAC (Australia) from January 2011 to August 2021 were reviewed, with data qualitatively synthesized to identify themes. Results: Forty-eight oncology submissions using EC arms between 2011 and 2021 were identified, with most submissions encompassing blood and bone marrow cancers (52%). In HTA submissions to NICE and PBAC, the EC arm was typically constructed from a combination of data sources, with the company's justification in data source selection infrequently provided (PBAC [2 out of 19]; NICE [6 out of 29]), although this lack of justification was not heavily criticized by either HTA body. Conclusion: Although HTA bodies such as NICE and PBAC encourage that EC source justification should be provided in submissions, this review found that this is not typically implemented in practice. Guidance is needed to establish best practices as to how EC selection should be documented in HTA submissions.

Competing Interests: Competing interests: GS and AF are employed by Cytel Inc. JE and DD are employed by NICE.

Failure to adjust for effect modifiers (EMs) in indirect treatment comparisons (ITCs) can produce biased and uncertain effect estimates. This is particularly important for health technology assessments (HTAs), where the availability of new treatments is based on comparative effectiveness results. Much emphasis has been placed on advancing ITC methods to adjust for EMs, yet whether EMs are appropriately identified for the conduct of ITCs in the first place is unclear. To understand the extent of guidance and requirements for the selection of EMs for ITCs currently available and if and how this guidance is applied in practice, a series of pragmatic reviews of guidance documents from HTA and non-payer organizations, primary published ITC analyses, and prior HTA submissions in two indications (non-small cell lung cancer and psoriasis) was conducted. The reviews showed that current ITC guidance mainly focused on developing analytical methods to adjust for EMs. Some organizations, such as HTA bodies in the UK, France and Germany, recommended the use of literature reviews, expert opinion and statistical methods to identify EMs. No detailed guidance on the selection process or the appropriate literature review approach was found. Similar trends were identified through the database search and review of prior HTA submissions; only few published ITCs and submissions included information on the EM selection process which was either based on findings from the literature, trial subgroup analyses, or clinical input. No reference to a systematic selection approach was found. There is an urgent need to fill the guidance gap identified across the reviews by including a step in ITC guidelines on how EMs should be identified through systematic reviews, formal expert elicitation, and a quantitative assessment of the EM distribution. Researchers and manufacturers are also encouraged to improve transparent reporting and justification of their selection of EMs to allow for an independent review of the set of factors being considered for adjustment. Both will contribute toward reducing bias in the ITC results and ultimately increase confidence in decision-making.

During the coronavirus disease 2019 (COVID-19) pandemic, the urgency for updated evidence to inform public health and clinical care placed systematic literature reviews (SLRs) at the cornerstone of research. We aimed to summarize evidence on prognostic factors for COVID-19 outcomes through published SLRs and to critically assess quality elements in the findings' interpretation. An umbrella review was conducted via electronic databases from January 2020 to April 2022. All SLRs (and meta-analyses) in English were considered. Data screening and extraction were conducted by two independent reviewers. AMSTAR 2 tool was used to assess SLR quality. The study was registered with PROSPERO (CRD4202232576). Out of 4,564 publications, 171 SLRs were included of which 3 were umbrella reviews. Our primary analysis included 35 SLRs published in 2022, which incorporated studies since the beginning of the pandemic. Consistent findings showed that, for adults, older age, obesity, heart disease, diabetes, and cancer were more strongly predictive of risk of hospitalization, intensive care unit admission, and mortality due to COVID-19. Male sex was associated with higher risk of short-term adverse outcomes, but female sex was associated with higher risk of long COVID. For children, socioeconomic determinants that may unravel COVID-19 disparities were rarely reported. This review highlights key prognostic factors of COVID-19, which can help clinicians and health officers identify high-risk groups for optimal care. Findings can also help optimize confounding adjustment and patient phenotyping in comparative effectiveness research. A living SLR approach may facilitate dissemination of new findings. This paper is endorsed by the International Society for Pharmacoepidemiology., (© 2023 The Authors. Clinical Pharmacology & Therapeutics © 2023 American Society for Clinical Pharmacology and Therapeutics.)

Health technology assessment (HTA) has traditionally relied on cost-effectiveness analysis (CEA) as a cornerstone of evaluation of new therapies, assessing the clinical validity and utility, the efficacy, and the cost-effectiveness of new interventions. The current format of cost-effectiveness analysis, however, does not allow for inclusion of more holistic aspects of health and, therefore, value elements for new technologies such as the impact on patients and society beyond its pure clinical and economic value. This study aimed to review the recent modelling attempts to expand the traditional cost-effectiveness analysis approach by incorporating additional elements of value in health technology assessment. A pragmatic literature review was conducted for articles published between 2012 and 2022 reporting cost-effectiveness analysis including value aspects beyond the clinical and cost-effectiveness estimates; searches identified 13 articles that were eligible for inclusion. These expanded modelling approaches mainly focused on integrating the impact of societal values and health equity in cost-effectiveness analysis, both of which were championed as important aspects of health technology assessment that should be incorporated into future technology assessments. The reviewed cost-effectiveness analysis methods included modification of the current cost-effectiveness analysis methodology (distributional cost-effectiveness analysis, augmented cost-effectiveness analysis, extended cost-effectiveness analysis) or the use of multi-criteria decision analysis. Of these approaches, augmented cost-effectiveness analysis appears to have the most potential by expanding traditional aspects of value, as it uses techniques already familiar to health technology assessment agencies but also allows space for incorporation of qualitative aspects of a product's value. This review showcases that methods to unravel additional value elements for technology assessment exist, therefore, patient access to promising technologies can be improved by moving the discussion from "if" to "how" additional value elements can inform decision-making., Competing Interests: Authors JM, GS, AR, and AF were employed by Cytel, Inc. Author IO was employed by Takeda Pharmaceuticals, Inc., (Copyright © 2023 Muir, Radhakrishnan, Freitag, Ozer Stillman and Sarri.)

As the scientific research community along with healthcare professionals and decision makers around the world fight tirelessly against the coronavirus disease 2019 (COVID-19) pandemic, the need for comparative effectiveness research (CER) on preventive and therapeutic interventions for COVID-19 is immense. Randomized controlled trials markedly under-represent the frail and complex patients seen in routine care, and they do not typically have data on long-term treatment effects. The increasing availability of electronic health records (EHRs) for clinical research offers the opportunity to generate timely real-world evidence reflective of routine care for optimal management of COVID-19. However, there are many potential threats to the validity of CER based on EHR data that are not originally generated for research purposes. To ensure unbiased and robust results, we need high-quality healthcare databases, rigorous study designs, and proper implementation of appropriate statistical methods. We aimed to describe opportunities and challenges in EHR-based CER for COVID-19-related questions and to introduce best practices in pharmacoepidemiology to minimize potential biases. We structured our discussion into the following topics: (1) study population identification based on exposure status; (2) ascertainment of outcomes; (3) common biases and potential solutions; and (iv) data operational challenges specific to COVID-19 CER using EHRs. We provide structured guidance for the proper conduct and appraisal of drug and vaccine effectiveness and safety research using EHR data for the pandemic. This paper is endorsed by the International Society for Pharmacoepidemiology (ISPE)., (© 2022 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Competing Interests: Author GS was employed by the company Cytel Inc.

Introduction: Cerebral vasospasm (VSP) is the leading risk factor of neurological deterioration (i.e., delayed cerebral ischemia [DCI] and cerebral infarction) after aneurysmal subarachnoid hemorrhage (aSAH) and a cause of morbidity and mortality. The objective of this systematic literature review is to summarize the economic and humanistic burden of VSP and its related complications after aSAH., Methods: A predefined protocol was designed, and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Systematic searches were conducted in MEDLINE, Embase, and Cochrane (in January 2021) to identify studies reporting economic and/or humanistic (i.e., health-related quality of life [HRQoL]) outcomes for patients with asymptomatic and symptomatic VSP after aSAH. Related conferences and additional sources were searched manually. Dual screening, data extraction, and qualitative analysis were conducted., Results: Of 3818 abstracts identified for review, 43 full-text articles representing 42 single studies met the inclusion criteria and were included. Most studies (33) were observational; nine were randomized clinical trials (RCTs). Economic outcomes were reported in 31 studies, and alongside HRQoL outcomes in 4 studies; 7 studies reported HRQoL outcomes only. Forty studies were conducted in single countries, while only 2 RCTs were conducted in multiple countries. Patients diagnosed with VSP or DCI spent between 2.1 and 7.4 days longer in intensive care and between 4.7 and 17 days longer in hospital (total) compared with patients without VSP or DCI. A significantly higher cost burden of US$33,945 (2021 £26,712) was identified for patients with VSP and £9370 (2021 £13,733) for patients with DCI compared with patients without. Patients with DCI were also disadvantaged by being employed for 62 fewer days (during 24-month follow-up), with an estimated mean cost of £3821 (2021 £5600) for days off work. Poor HRQoL was associated with ≥ 1 days with VSP symptoms (odds ratio [OR]: 2.8, 95% confidence interval [CI]: 1.4-5.3), symptomatic VSP (OR: 1.9, 95% CI: 1.0-3.6), and DCI (OR: 2.3, 95% CI: 1.3-4.2), although this was not consistent across all studies. Symptomatic VSP and DCI were identified as significant risk factors for depressed mood (OR: 2.2, 95% CI: 1.0-4.9) and global cognitive impairment (OR: 2.3) at 12 months, respectively. The severity of VSP was a critical predictor of post-aSAH economic and humanistic burden. Similar trends in economic and humanistic burden were identified in the general aSAH patient population. Study design and patient heterogeneity precluded direct metaanalysis of the results., Conclusion: A substantial direct and indirect economic burden is linked to VSP and its related complications after aSAH. Although limited evidence was identified for humanistic burden, these patients seem to suffer from poor HRQoL with long-lasting burden. Overall, there is an urgent need to understand better the concept of "burden of illness" of VSP and its related complications after aSAH., (© 2022. The Author(s).)

Objective . In the irradiation of living tissue, the fundamental physical processes involved in radical production typically occur on a timescale of a few femtoseconds. A detailed understanding of these phenomena has thus far been limited by the relatively long duration of the radiation sources employed, extending well beyond the timescales for radical generation and evolution. Approach . Here, we propose a femtosecond-scale photon source, based on inverse Compton scattering of laser-plasma accelerated electron beams in the field of a second scattering laser pulse. Main results . Detailed numerical modelling indicates that existing laser facilities can provide ultra-short and high-flux MeV-scale photon beams, able to deposit doses tuneable from a fraction of Gy up to a few Gy per pulse, resulting in dose rates exceeding 10 13 Gy/s. Significance . We envisage that such a source will represent a unique tool for time-resolved radiobiological experiments, with the prospect of further advancing radio-therapeutic techniques., (Creative Commons Attribution license.)

Introduction: High-quality randomised controlled trials (RCTs) provide the most reliable evidence on the comparative efficacy of new medicines. However, non-randomised studies (NRS) are increasingly recognised as a source of insights into the real-world performance of novel therapeutic products, particularly when traditional RCTs are impractical or lack generalisability. This means there is a growing need for synthesising evidence from RCTs and NRS in healthcare decision making, particularly given recent developments such as innovative study designs, digital technologies and linked databases across countries. Crucially, however, no formal framework exists to guide the integration of these data types., Objectives and Methods: To address this gap, we used a mixed methods approach (review of existing guidance, methodological papers, Delphi survey) to develop guidance for researchers and healthcare decision-makers on when and how to best combine evidence from NRS and RCTs to improve transparency and build confidence in the resulting summary effect estimates., Results: Our framework comprises seven steps on guiding the integration and interpretation of evidence from NRS and RCTs and we offer recommendations on the most appropriate statistical approaches based on three main analytical scenarios in healthcare decision making (specifically, 'high-bar evidence' when RCTs are the preferred source of evidence, 'medium,' and 'low' when NRS is the main source of inference)., Conclusion: Our framework augments existing guidance on assessing the quality of NRS and their compatibility with RCTs for evidence synthesis, while also highlighting potential challenges in implementing it. This manuscript received endorsement from the International Society for Pharmacoepidemiology., Competing Interests: Competing interests: We have read and understood BMJ Evidence-Based Medicine policy on declaration of interests and declare the following interests: GS is employed by Visible Analytics, Ltd; DB is employed by Takeda; ARZ holds a grant from Sanofi Pasteur (direct to institution); MP owns stocks from Merck, Sanofi, and Johnson & Johnson; MG is employed by GSK; and TD is an advisor to pharma industry., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: Many targeted, systemic therapies have been developed for treatment of moderate-to-severe psoriasis (PsO). A network meta-analysis (NMA) allows for comparison between treatments not directly compared in randomized controlled trials (RCT). This study's objective was to compare the short-term (10-16 weeks) clinical efficacy according to the Psoriasis Area and Severity Index (PASI) among approved biologic treatments for moderate-to-severe PsO using a novel (enhanced) NMA model., Methods: A systematic literature review (SLR) of RCTs for patients with moderate-to-severe PsO was conducted. English publications in MEDLINE, Embase, and The Cochrane Library up to March 2019 were searched. An enhanced multinomial Bayesian NMA was performed to simultaneously adjust for baseline risk and utilize the conditional nature of the PASI (50, 75, 90, and 100) levels. The model relaxes typical constraints that all treatments must have the same ranks across PASI levels., Results: The SLR resulted in 319 relevant publications, of which 72 publications from 73 RCTs reporting 10- to 16-week data for at least one PASI response level (30,314 total patients) were included. Interleukin (IL) inhibitors (risankizumab, ixekizumab, brodalumab, secukinumab, and guselkumab) were the best performing treatments for achieving all PASI levels. Etanercept was outperformed by the other subcutaneous tumor necrosis factor α inhibitors. Application of an enhanced NMA model that allowed treatment rankings to differ by PASI level tested the robustness of results of previous NMAs in PsO., Conclusion: The results of this model confirmed that IL inhibitors are likely the best short-term treatment choices for improving all PASI levels., (© 2021. The Author(s).)

Introduction: Single-agent belantamab mafodotin (belamaf; BLENREP) demonstrated deep and durable responses in patients with relapsed/refractory multiple myeloma and ≥ 3 prior lines of therapy, including an immunomodulatory agent, proteasome inhibitor, and anti-CD38 antibody (DREAMM-2; NCT03525678)., Methods: At the time of this study, STORM Part 2, NCT02336815 (selinexor plus low-dose dexamethasone; sel + dex) was systematically identified as the only feasible comparator to the DREAMM-2 cohort. Matching-adjusted indirect comparisons (MAIC) evaluated efficacy and safety of belamaf (2.5 mg/kg; n = 97) versus sel + dex (80 mg + 20 mg, respectively; n = 123). Populations were weighted for clinically validated effect modifiers and prognostic factors. Outcomes included overall survival (OS), progression-free survival (PFS), duration of response (DoR), overall response rate (ORR), time to response (TTR), and safety. The relative efficacy of belamaf versus standard of care (SoC) on OS was estimated by a Bucher indirect treatment comparison using the MAIC-adjusted hazard ratios (HR) for OS of belamaf (DREAMM-2) versus sel + dex (STORM Part 2) and a HR adjusted for refractoriness to carfilzomib and high-risk cytogenetics of sel + dex (STORM) versus SoC (MAMMOTH)., Results: Belamaf demonstrated improved OS (HR 0.53; 95% confidence interval 0.34, 0.83; p = 0.005) and DoR (0.41; 0.21, 0.83; p = 0.013) versus sel + dex. There were no statistically significant differences in ORR, TTR, and PFS. Belamaf had a favorable safety profile for most evaluable hematologic (any-grade, Grade 3-4) and non-hematologic (any-grade) adverse events versus sel + dex. Significantly improved OS was observed with belamaf versus SoC (0.29; 0.16, 0.54; p < 0.001)., Conclusion: Single-agent belamaf represents a new treatment option for triple-class refractory patients with RRMM., (© 2021. The Author(s).)

Objective: Neurodevelopmental impairment (NDI) is a major complication of extreme prematurity. This systematic review was conducted to summarize the worldwide long-term prevalence of NDI associated with extreme prematurity., Methods: Embase and MEDLINE databases were searched for epidemiologic and observational/real-world studies, published in English between 2011 and 2016, reporting long-term prevalence of NDI (occurring from 1 year) among extremely preterm infants born at gestational age (GA) ≤28 weeks., Results: Of 2406 articles identified through searches, 69 met the protocol NDI definition (24 North America, 25 Europe, 20 Rest of World). Prevalence of any severity NDI in North America was 8%-59% at 18 months to 2 years, and 11%-37% at 2-5 years; prevalence of moderate NDI in Europe was 10%-13% at 18 months to 2 years, 3% at 2-5 years, and 9%-19% at ≥5 years; prevalence of any NDI in Rest of World was 15%-61% at 18 months to 2 years, and 42% at 2-5 years (no North America/Rest of World studies reported any NDI at ≥5 years). A trend toward higher prevalence of NDI with lower GA at birth was observed., Conclusions: Extreme prematurity has a significant long-term worldwide impact on neurodevelopmental outcomes.

Objective: To determine whether assessment tools for non-randomised studies (NRS) address critical elements that influence the validity of NRS findings for comparative safety and effectiveness of medications., Design: Systematic review and Delphi survey., Data Sources: We searched PubMed, Embase, Google, bibliographies of reviews and websites of influential organisations from inception to November 2019. In parallel, we conducted a Delphi survey among the International Society for Pharmacoepidemiology Comparative Effectiveness Research Special Interest Group to identify key methodological challenges for NRS of medications. We created a framework consisting of the reported methodological challenges to evaluate the selected NRS tools., Study Selection: Checklists or scales assessing NRS., Data Extraction: Two reviewers extracted general information and content data related to the prespecified framework., Results: Of 44 tools reviewed, 48% (n=21) assess multiple NRS designs, while other tools specifically addressed case-control (n=12, 27%) or cohort studies (n=11, 25%) only. Response rate to the Delphi survey was 73% (35 out of 48 content experts), and a consensus was reached in only two rounds. Most tools evaluated methods for selecting study participants (n=43, 98%), although only one addressed selection bias due to depletion of susceptibles (2%). Many tools addressed the measurement of exposure and outcome (n=40, 91%), and measurement and control for confounders (n=40, 91%). Most tools have at least one item/question on design-specific sources of bias (n=40, 91%), but only a few investigate reverse causation (n=8, 18%), detection bias (n=4, 9%), time-related bias (n=3, 7%), lack of new-user design (n=2, 5%) or active comparator design (n=0). Few tools address the appropriateness of statistical analyses (n=15, 34%), methods for assessing internal (n=15, 34%) or external validity (n=11, 25%) and statistical uncertainty in the findings (n=21, 48%). None of the reviewed tools investigated all the methodological domains and subdomains., Conclusions: The acknowledgement of major design-specific sources of bias (eg, lack of new-user design, lack of active comparator design, time-related bias, depletion of susceptibles, reverse causation) and statistical assessment of internal and external validity is currently not sufficiently addressed in most of the existing tools. These critical elements should be integrated to systematically investigate the validity of NRS on comparative safety and effectiveness of medications. SYSTEMATIC REVIEW PROTOCOL AND REGISTRATION: https://osf.io/es65q., Competing Interests: Competing interests: DB is an employee of Takeda. ARZ has received salary support from Sanofi Pasteur through a grant to Brown University unrelated to the current work. TD provides consulting services via Smart Data Analysis and Statistics. GS discloses being employed by Visible Analytics Ltd., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Cardiac masses are space occupying lesions within the cardiac cavities or adjacent to the pericardium. They include frequently diagnosed clinical entities such as clots and vegetations, common benign tumors such as myxomas and papillary fibroelastomas and uncommon benign or malignant primary or metastatic tumors. Given their diversity, there are no guidelines or consensus statements regarding the best diagnostic or therapeutic approach. In the past, diagnosis used to be made by the histological specimens after surgery or during the post-mortem examination. Nevertheless, evolution and increased availability of cardiovascular imaging modalities has enabled better characterization of the masses and the surrounding tissue. Transthoracic echocardiography using contrast agents can evaluate the location, the morphology and the perfusion of the mass as well as its hemodynamic effect. Transesophageal echocardiography has increased spatial and temporal resolution; hence it is superior in depicting small highly mobile masses. Cardiac magnetic resonance and cardiac computed tomography are complementary providing tissue characterization. The scope of this review is to present the role of cardiovascular imaging in the differential diagnosis of cardiac masses and to propose a step-wise diagnostic algorithm, taking into account the epidemiology and clinical presentation of the cardiac masses, as well as the availability and the incremental value of each imaging modality.

Purpose: To systematically estimate the patient-reported outcomes (PROs) and economic burden of sickle cell disease (SCD) among adults in the United States (US)., Patients and Methods: Two systematic literature reviews (SLRs), one each for the PROs and economic topics, were performed using MEDLINE and Embase to identify observational studies of adults with SCD. Included studies were published between 2007 and 2018 and evaluated health-related quality of life (HRQL), function, healthcare resource utilization (HCRU), or costs. Given the high degree of clinical and methodological heterogeneity, findings were summarized qualitatively., Results: The SLRs identified 7 studies evaluating the PROs and 15 studies evaluating the economic burden meeting the pre-specified selection criteria. The PRO evidence showed the prevalence of depression and anxiety to be 21-33% and 7-36%, respectively, in adults with SCD. The mean SF-36 physical summary scores ranged from 33.6 to 59.0 and from 46.3 to 61.5 for the mental summary scores. Overall HRQL for adults with SCD was poor and significantly worse in those with opioid use. Adult SCD patients were found to have varying rates of emergency department (ED) utilization (0.3-3.5 annual ED visits), hospitalizations (0.5-27.9 per patient per year), and/or readmission (12-41%). Key factors associated with significant HCRU were age, dental infection, and SCD-related complications. SCD specialized care settings and SCD intensive management strategy were reported to significantly decrease the number of hospitalizations., Conclusion: This systematic evidence synthesis found that disease burden measured by PROs and economic burden of SCD on adults in the US are substantial despite the availability of approved SCD treatments during 2007-2018. The use of hydroxyurea, optimal management with opioids, and employing intensive treatment strategies may help decrease the overall burden to patients and healthcare systems. Published data on costs associated with SCD are limited and highlight the need for more economic studies to characterize the full burden of the disease., Competing Interests: SL and MB are employed by Novartis. DV and GS are employed by Evidera, which provides consulting and other research services to pharmaceutical, medical device, and related organizations. DR and SA were employees of Evidera at the time this study was executed. In their salaried positions, they work with a variety of companies and organizations, and are precluded from receiving payment or honoraria directly from these organizations for services rendered. MB reports grants from Novartis, during the conduct of the study; personal fees from Amgen, outside the submitted work. DR reports grants from Novartis, during the conduct of the study; personal fees from Amgen, outside the submitted work. The authors report no other conflicts of interest in this work., (© 2020 Lee et al.)

Background: The ease of implantation of the rapid deployment (RD) and sutureless valves has contributed to the adoption of anterior right thoracotomy (ART) approach for aortic valve replacement (AVR)., Aim of the Study: This study evaluates the safety and haemodynamic performance of minimally invasive AVR through ART using the RD valves., Methods: This is a retrospective, single-center review of a total of 50 consecutive patients who received RD-AVR through ART., Results: The median age of patients was 75 years (interquartile range [IQR]: 69-80), and median Euroscore II was 5.1 (IQR: 2.4-7.5). ART RD-AVR was successfully performed in all cases with no conversion to sternotomy, paravalvular leaks or need for valve explantation. The mean size of the implanted valve was 23.2  ± 2.3 mm. In-hospital mortality was 2%. The mean and maximum pressure gradients across the aortic prosthesis were 10 mm Hg (IQR: 9-12) and 19 mm Hg (IQR: 16-23)., Conclusions: Rapid deployment aortic valve replacement can be safely performed through anterior right thoracotomy wit excellent haemodynamic performance and low postoperative complications rate., (© 2020 Wiley Periodicals, Inc.)

We present here a novel scheme for the high-resolution spectrometry of high-flux gamma-ray beams with energies per photon in the multi-GeV range. The spectrometer relies on the conversion of the gamma-ray photons into electron-positron pairs in a solid foil with high atomic number. The measured electron and positron spectra are then used to reconstruct the spectrum of the gamma-ray beam. The performance of the spectrometer has been numerically tested against the predicted photon spectra expected from non-linear Compton scattering in the proposed LUXE experiment, showing high fidelity in identifying distinctive features such as Compton edges and non-linearities.

Through a nature-inspired layer-by-layer assembly process, we developed a unique multifunctional tissue scaffold that consists of porous polyurethane substrate and nanoscale chitosan/graphene oxide hybrid coating. Alternative layers of drug-laden chitosan and graphene oxide nanosheets were held together through strong electrostatic interaction, giving rise to a robust multilayer architecture with control over structural element orientation and chemical composition at nanoscale. Combined pH-controlled co-delivery of multiple therapeutic agents and photothermal therapy has been achieved by our scaffold system. The new platform technology can be generalized to produce other tissue scaffold systems and may enable potential multimodal therapeutic applications such as bone cancer managements.

The intrinsic constraints in the amplitude of the accelerating fields sustainable by radio-frequency accelerators demand for the pursuit of alternative and more compact acceleration schemes. Among these, plasma-based accelerators are arguably the most promising, thanks to the high-accelerating fields they can sustain, greatly exceeding the GeV/m. While plasma-based acceleration of electrons is now sufficiently mature for systematic studies in this direction, positron acceleration is still at its infancy, with limited projects currently undergoing to provide a viable test facility for further experiments. In this article, we study the feasibility of using a recently demonstrated laser-driven configuration as a relatively compact and inexpensive source of high-quality ultra-relativistic positrons for laser-driven and particle-driven plasma wakefield acceleration studies. Monte-Carlo simulations show that near-term high-intensity laser facilities can produce positron beams with high-current, femtosecond-scale duration, and sufficiently low normalised emittance at energies in the GeV range to be injected in further acceleration stages.

Objectives: Accumulating evidence suggests a direct role of Uric Acid (UA) on Left Ventricular (LV) diastolic function in chronic kidney disease and Heart Failure (HF) patients. Recently, UA has been linked to LV Hypertrophy (LVH) and Diastolic Dysfunction (DD) in women with preserved Ejection Fraction (pEF) but not in corresponding men. We sought to assess if UA could predict indices of DD in hypertensive subjects with pEF independently of gender., Method: We consecutively recruited 382 apparently healthy hypertensive subjects (age: 61.7±10.7, women: 61.3%, median EF: 64%). In 318 patients in sinus rhythm, LV mass-indexed to body surface area-was calculated (LVMI). LVH was set as an LVMI >116g/m2 or 96 g/m2 in men and women, respectively. The ratio of early transmitral peak velocity (E) to the mitral annular early diastolic velocity (Em) was used as an approximation of mean left atrial pressure (E/Em)., Results: UA [median (interquartile range): 5.4(2) mg/dl] independently predicted E/Em (adjusted coefficient: 1.01, p =0.026) while an interaction term between gender and UA was no significant (p=0.684). An ordinal score of DD was calculated taking into account increased E/Em, left atrium dilatation and LVH. Women with increased UA had 254% increased odds (adjusted OR=2.54, p=0.005) to be classified in the upper range of the DD score., Conclusion: In hypertensive subjects without HF, UA is independently associated with the presence of DD in both genders and correlates with its severity in women. Further prospective studies are warranted to evaluate the association of UA with adverse cardiovascular outcomes in high-risk populations such as HF with pEF., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.

Background: Neonatal calf diarrhea is generally caused by infectious agents and is a very common disease in bovine practice, leading to substantial economic losses. Tannins are known for their astringent and anti-inflammatory properties in the gastro-enteric tract. The aim of this study was to evaluate the effect of the oral administration of chestnut tannins (Castanea sativa Mill.) in order to reduce the duration of calf neonatal diarrhea. Twenty-four Italian Friesian calves affected by neonatal diarrhea were included. The duration of the diarrheic episode (DDE) was recorded and the animals were divided into a control group (C), which received Effydral® in 2 l of warm water, and a tannin-treated group (T), which received Effydral® in 2 l of warm water plus 10 g of extract of chestnut tannins powder. A Mann-Whitney test was performed to verify differences for the DDE values between the two groups., Results: The DDE was significantly higher in group C than in group T (p = 0.02), resulting in 10.1 ± 3.2 and 6.6 ± 3.8 days, respectively., Conclusions: Phytotherapic treatments for various diseases have become more common both in human and in veterinary medicine, in order to reduce the presence of antibiotic molecules in the food chain and in the environment. Administration of tannins in calves with diarrhea seemed to shorten the DDE in T by almost 4 days compared to C, suggesting an effective astringent action of chestnut tannins in the calf, as already reported in humans. The use of chestnut tannins in calves could represent an effective, low-impact treatment for neonatal diarrhea.

In the field of X-ray microcomputed tomography (μCT) there is a growing need to reduce acquisition times at high spatial resolution (approximate micrometers) to facilitate in vivo and high-throughput operations. The state of the art represented by synchrotron light sources is not practical for certain applications, and therefore the development of high-brightness laboratory-scale sources is crucial. We present here imaging of a fixed embryonic mouse sample using a compact laser-plasma-based X-ray light source and compare the results to images obtained using a commercial X-ray μCT scanner. The radiation is generated by the betatron motion of electrons inside a dilute and transient plasma, which circumvents the flux limitations imposed by the solid or liquid anodes used in conventional electron-impact X-ray tubes. This X-ray source is pulsed (duration <30 fs), bright (>10 10 photons per pulse), small (diameter <1 μm), and has a critical energy >15 keV. Stable X-ray performance enabled tomographic imaging of equivalent quality to that of the μCT scanner, an important confirmation of the suitability of the laser-driven source for applications. The X-ray flux achievable with this approach scales with the laser repetition rate without compromising the source size, which will allow the recording of high-resolution μCT scans in minutes., Competing Interests: The authors declare no conflict of interest., (Copyright © 2018 the Author(s). Published by PNAS.)

In this paper we report the experimental implementation of a theoretically proposed technique for creating a photoionized plasma in the laboratory using x-ray line radiation. Using a Sn laser plasma to irradiate an Ar gas target, the photoionization parameter, ξ=4πF/N&#95;{e}, reached values of order 50ergcms^{-1}, where F is the radiation flux in ergcm^{-2}s^{-1}. The significance of this is that this technique allows us to mimic effective spectral radiation temperatures in excess of 1 keV. We show that our plasma starts to be collisionally dominated before the peak of the x-ray drive. However, the technique is extendable to higher-energy laser systems to create plasmas with parameters relevant to benchmarking codes used to model astrophysical objects.

Background: Sickle cell disease (SCD) is a chronic condition associated with high mortality and morbidity. It is characterized by acute clinical symptoms such as painful vaso-occlusive crises, which can impair health-related quality of life (HRQL). This study was conducted to identify validated patient-reported outcome (PRO) instruments for use in future trials of potential treatments for SCD., Methods: A systematic literature review (SLR) was performed using MEDLINE and EMBASE to identify United States (US)-based studies published in English between 1997 and 2017 that reported on validated PRO instruments used in randomized controlled trials and real-world settings. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist was used to assess the quality of PRO instruments., Results: The SLR included 21 studies assessing the psychometric properties of 24 PRO instruments. Fifteen of those instruments were developed and validated for adults and 10 for children (one instrument was used in both children and young adults aged up to 21 years). Only five of the 15 adult instruments and three of the 10 pediatric instruments were developed specifically for SCD. For most instruments, there were few or no data on validation conducted in SCD development cohorts. Of the 24 PRO instruments identified, 16 had strong internal reliability (Cronbach's α ≥0.80). There was often insufficient information to assess the content validity, construct validity, responsiveness, or test-retest reliability of the instruments identified for both child and adult populations. No validated PRO instruments measuring caregiver burden in SCD were identified., Conclusions: The evidence on the psychometric properties of PRO instruments was limited. However, the results of this SLR provide key information on such tools to help inform the design of future clinical trials for patients with SCD in the US.

We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥1  T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of ε&#95;{B}≈10^{-3} is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.

Background: Vasomotor symptoms (VMSs) are the hallmarks of menopause, occurring in approximately 75% of postmenopausal women in the UK, and are severe in 25%., Objectives: To identify which treatments are most clinically effective for the relief of VMSs for women in natural menopause without hysterectomy., Search Strategy: English publications in MEDLINE, Embase, and The Cochrane Library up to 13 January 2015 were searched., Selection Criteria: Randomised controlled trials (RCTs) of treatments for women with a uterus for the outcomes of frequency of VMSs (up to 26 weeks), vaginal bleeding, and discontinuation., Data Collection and Analysis: Bayesian network meta-analysis (NMA) using mean ratios (MRs) and odd ratios (ORs)., Main Results: Across the three networks, 47 RCTs of 16 treatment classes (n = 8326 women) were included. When compared with placebo, transdermal estradiol and progestogen (O+P) had the highest probability of being the most effective treatment for VMS relief (69.8%; MR 0.23; 95% credible interval, 95% CrI 0.09-0.57), whereas oral O+P was ranked lower than transdermal O+P, although oral and transdermal O+P were no different for this outcome (MR 2.23; 95% CrI 0.7-7.1). Isoflavones and black cohosh were more effective than placebo, although not significantly better than O+P. Not only were selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) found to be ineffective in relieving VMSs, but they also had significantly higher odds of discontinuation than placebo. Limited data were available for bleeding, therefore no conclusions could be made., Conclusion: For women who have not undergone hysterectomy, transdermal O+P was the most effective treatment for VMS relief., Tweetable Abstract: Which treatment best relieves menopause flushes? Results from the #NICE guideline network meta-analysis., (© 2017 Royal College of Obstetricians and Gynaecologists.)

As more complex meta-analytical techniques such as network and multivariate meta-analyses become increasingly common, further pressures are placed on reviewers to extract data in a systematic and consistent manner. Failing to do this appropriately wastes time, resources and jeopardises accuracy. This guide (data extraction for complex meta-analysis (DECiMAL)) suggests a number of points to consider when collecting data, primarily aimed at systematic reviewers preparing data for meta-analysis. Network meta-analysis (NMA), multiple outcomes analysis and analysis combining different types of data are considered in a manner that can be useful across a range of data collection programmes. The guide has been shown to be both easy to learn and useful in a small pilot study.

The temporal contrast of a regeneratively amplified, sub-picosecond pulse is enhanced by employing a low-gain optical parametric amplification stage self-pumped by the second harmonic of the pulse. Through careful characterization of the two related nonlinear processes and optimization of the non-collinear geometry, a robust high-contrast idler pulse has been generated, with excellent spatial quality in both the near and far field. The overall energy conversion efficiency exceeds 14%, with 33% intensity conversion efficiency. The temporal cleaning is implemented without any bandwidth losses or spectral shift and produces approximately 20% temporal shortening. These experimental findings are in excellent agreement with numerical calculations.

We present a comprehensive model for predicting the full performance of a second harmonic generation-optical parametric amplification system that aims at enhancing the temporal contrast of laser pulses. The model simultaneously takes into account all the main parameters at play in the system such as the group velocity mismatch, the beam divergence, the spectral content, the pump depletion, and the length of the nonlinear crystals. We monitor the influence of the initial parameters of the input pulse and the interdependence of the two related non-linear processes on the performance of the system and show its optimum configuration. The influence of the initial beam divergence on the spectral and the temporal characteristics of the generated pulse is discussed. In addition, we show that using a crystal slightly longer than the optimum length and introducing small delay between the seed and the pump ensures maximum efficiency and compensates for the spectral shift in the optical parametric amplification stage in case of chirped input pulse. As an example, calculations for bandwidth transform limited and chirped pulses of sub-picosecond duration in beta barium borate crystal are presented.

Temporal overlapping of ultra-short and focussed laser pulses is a particularly challenging task, as this timescale lies orders of magnitude below the typical range of fast electronic devices. Here we present an optical technique that allows for the measurement of the temporal delay between two focussed and ultra-short laser pulses. This method is virtually applicable to any focussing geometry and relative intensity of the two lasers. Experimental implementation of this technique provides excellent quantitative agreement with theoretical expectations. The proposed technique will prove highly beneficial for high-power multiple-beam laser experiments.