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Longitudinal clustering provides a detailed yet comprehensible description of time profiles among subjects. With several approaches that are commonly used for this purpose, it remains unclear under which conditions a method is preferred over another method. We investigated the performance of five methods using Monte Carlo simulations on synthetic datasets, representing various scenarios involving polynomial time profiles. The performance was evaluated on two aspects: The agreement of the group assignment to the simulated reference, as measured by the split-join distance, and the trend estimation error, as measured by a weighted minimum of the mean squared error (WMMSE). Growth mixture modeling (GMM) was found to achieve the best overall performance, followed closely by a two-step approach using growth curve modeling and k-means (GCKM). Considering the model similarities between GMM and GCKM, the latter is preferred for large datasets for its computational efficiency. Longitudinal k-means (KML) and group-based trajectory modeling were found to have practically identical solutions in the case that the group trajectory model of the latter method is correctly specified. Both methods performed less than GMM and GCKM in most settings. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to establish the determinants of perceived sleep quality over a longer period of time, taking into account the separate contributions of actigraphy-based sleep measures and self-reported sleep indices. Methods: Fifty participants (52 ± 6.6 years; 27 females) completed two consecutive weeks of home monitoring, during which they kept a sleep–wake diary while their sleep was monitored using a wrist-worn actigraph. The diary included questions on perceived sleep quality, sleep–wake information, and additional factors such as well-being and stress. The data were analyzed using multilevel models to compare a model that included only actigraphy-based sleep measures (model Acti) to a model that included only self-reported sleep measures to explain perceived sleep quality (model Self). In addition, a model based on the self-reported sleep measures and extended with nonsleep-related factors was analyzed to find the most significant determinants of perceived sleep quality (model Extended). Results: Self-reported sleep measures (model Self) explained 61% of the total variance, while actigraphy-based sleep measures (model Acti) only accounted for 41% of the perceived sleep quality. The main predictors in the self-reported model were number of awakenings during the night, sleep onset latency, and wake time after sleep onset. In the extended model, the number of awakenings during the night and total sleep time of the previous night were the strongest determinants of perceived sleep quality, with 64% of the variance explained. Conclusion: In our cohort, perceived sleep quality was mainly determined by self-reported sleep measures and less by actigraphy-based sleep indices. These data further stress the importance of taking multiple nights into account when trying to understand perceived sleep quality. [ABSTRACT FROM AUTHOR]

Both open and endoscopic methods for ulnar nerve decompression have been described. The purpose of this study is to compare the 6-month results of a minimal invasive open technique with an endoscopic technique. We treated 60 patients with unilateral ulnar neuropathy at the elbow, employing both techniques. Six months postoperative we found no differences in treatment effect on pain and disability scores between both groups, but both techniques resulted in an early postoperative relief of symptoms and good patient satisfaction. [ABSTRACT FROM PUBLISHER]

Background: Multimorbidity may impose an overwhelming burden on patients with psychosis and is affected by gender and age. Our aim is to study the independent role of familial liability to psychosis as a risk factor for multimorbidity., Methods: We performed the study within the framework of the Genetic Risk and Outcome of Psychosis (GROUP) project. Overall, we compared 1024 psychotic patients, 994 unaffected siblings and 566 controls on the prevalence of 125 lifetime diseases, and 19 self-reported somatic complaints. Multimorbidity was defined as the presence of two or more complaints/diseases in the same individual. Generalized linear mixed model (GLMM) were used to investigate the effects of gender, age (adolescent, young, older) and familial liability (patients, siblings, controls) and their interactions on multimorbidity., Results: Familial liability had a significant effect on multimorbidity of either complaints or diseases. Patients had a higher prevalence of multimorbidity of complaints compared to siblings (OR 2.20, 95% CI 1.79-2.69, P<0.001) and to controls (3.05, 2.35-3.96, P<0.001). In physical health multimorbidity, patients (OR 1.36, 95% CI 1.05-1.75, P=0.018), but not siblings, had significantly higher prevalence than controls. Similar finding were observed for multimorbidity of lifetime diseases, including psychiatric diseases. Significant results were observed for complaints and disease multimorbidity across gender and age groups., Conclusion: Multimorbidity is a common burden, significantly more prevalent in patients and their unaffected siblings. Familial liability to psychosis showed an independent effect on multimorbidity; gender and age are also important factors determining multimorbidity., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Objective: Distribution of age of onset of recurrent respiratory papillomatosis (RRP) is generally described to be bimodal, with peaks at approximately 5 years and 30 years. This assumption has never been scientifically confirmed, and authors tend to refer to an article that does not describe distribution. Knowledge of the distribution of age of onset is important for virological and epidemiological comprehension. The objective of this study was to determine the distribution of age of onset of RRP in a large international sample., Design: Cross-sectional distribution analysis., Participants: Laryngologists from 12 European hospitals provided information on date of birth and date of onset of all their RRP patients treated between 1998 and 2012. Centers that exclusively treated either patients with juvenile onset RRP or patients with adult onset RRP, or were less accessible for one of these groups, were excluded to prevent skewness., Main Outcome Measures: A mixture model was implemented to describe distribution of age of onset. The best fitting model was selected using the Bayesian information criterion., Results: Six hundred and thirty-nine patients were included in the analysis. Age of onset was described by a three component mixture distribution with lognormally distributed components. Recurrent respiratory papillomatosis starts at three median ages 7, 35 and 64 years., Conclusions: Distribution of age of onset of RRP shows three peaks. In addition to the already adopted idea of age peaks at paediatric and adult age, there is an additional peak around the age of 64., (© 2015 John Wiley & Sons Ltd.)

Objectives: Minimalist running shoes have been proposed as an alternative to barefoot running. However, several studies have reported cases of forefoot stress fractures after switching from standard to minimalist shoes. Therefore, the aim of the current study was to investigate the differences in plantar pressure in the forefoot region between running with a minimalist shoe and running with a standard shoe in healthy female runners during overground running., Design: Randomized crossover design., Methods: In-shoe plantar pressure measurements were recorded from eighteen healthy female runners. Peak pressure, maximum mean pressure, pressure time integral and instant of peak pressure were assessed for seven foot areas. Force time integral, stride time, stance time, swing time, shoe comfort and landing type were assessed for both shoe types. A linear mixed model was used to analyze the data., Results: Peak pressure and maximum mean pressure were higher in the medial forefoot (respectively 13.5% and 7.46%), central forefoot (respectively 37.5% and 29.2%) and lateral forefoot (respectively 37.9% and 20.4%) for the minimalist shoe condition. Stance time was reduced with 3.81%. No relevant differences in shoe comfort or landing strategy were found., Conclusions: Running with a minimalist shoe increased plantar pressure without a change in landing pattern. This increased pressure in the forefoot region might play a role in the occurrence of metatarsal stress fractures in runners who switched to minimalist shoes and warrants a cautious approach to transitioning to minimalist shoe use., (Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Background: Shortening the duration of untreated psychosis (DUP) - with the aim of improving the prognosis of psychotic disorders - requires an understanding of the causes of treatment delay. Current findings concerning several candidate risk factors of a longer DUP are inconsistent. Our aim was to identify factors contributing to DUP in a large sample that represents the treated prevalence of non-affective psychotic disorders., Method: Patients with a non-affective psychotic disorder were recruited from mental health care institutes from 2004 to 2008. Of the 1120 patients enrolled, 852 could be included in the present analysis. Examined candidate factors were gender, educational level, migration status, premorbid adjustment and age at onset of the psychotic disorder. DUP was divided into five ordinal categories: less than one month, one month to three months, three months to six months, six months to twelve months and twelve months and over. An ordinal logistic regression analysis was used to identify the risk factors of a longer DUP., Results: Median DUP was less than one month (IQR 2). The factors migration status (p=0.028), age at onset of the psychotic disorder (p=0.003) and gender (p=0.034) were significantly associated with DUP in our analysis., Conclusion: First generation immigrant patients, patients with an early onset of their psychotic disorder and male patients seem at risk of a longer DUP. These findings can assist in designing specific interventions to shorten treatment delay., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Both open and endoscopic methods for ulnar nerve decompression have been described. The purpose of this study is to compare the 6-month results of a minimal invasive open technique with an endoscopic technique. We treated 60 patients with unilateral ulnar neuropathy at the elbow, employing both techniques. Six months postoperative we found no differences in treatment effect on pain and disability scores between both groups, but both techniques resulted in an early postoperative relief of symptoms and good patient satisfaction., (© The Author(s) 2013.)

The oral microbiome consists of a planktonic microbiome residing in saliva and an adhering microbiome (the biofilm adhering to oral hard and soft tissues). Here we hypothesized that possible differences in microbial composition of the planktonic and adhering oral microbiome on teeth can be related to the forces by which different bacterial species are attracted to the tooth surface. The relative presence of 7 oral bacterial species in saliva and biofilm collected from 10 healthy human volunteers was determined twice in each volunteer by denaturing-gradient-gel electrophoresis. Analysis of both microbiomes showed complete separation of the planktonic from the adhering oral microbiome. Next, adhesion forces of corresponding bacterial strains with saliva-coated enamel surfaces were measured by atomic force microscopy. Species that were found predominantly in the adhering microbiome had significantly higher adhesion forces to saliva-coated enamel (-0.60 to -1.05 nN) than did species mostly present in the planktonic microbiome (-0.40 to -0.55 nN). It is concluded that differences in composition of the planktonic and the adhering oral microbiome are due to small differences in the forces by which strains adhere to saliva-coated enamel, providing an important step in understanding site- and material-specific differences in the composition of biofilms in the oral cavity.

Objective: Epicardial adipose tissue (EAT) and mediastinal adipose tissue (MAT) are linked to coronary artery disease (CAD). The association between EAT, MAT, and severity of CAD in known extra-cardiac arterial disease was investigated., Design and Methods: Sixty-five cardiac asymptomatic patients (mean age 65 ± 8 years, 69% male) with peripheral arterial disease, carotid stenosis, or aortic aneurysm underwent coronary computed tomography angiography. Patients were divided into non-significant (<50% stenosis, N = 35), single vessel (N = 15) and multi-vessel CAD (N = 15). EAT and MAT were quantified on computed tomography images using volumetric software., Results: Subgroups did not significantly differ by age, gender, or cardiovascular risk factors. Median EAT was 99.5, 98.0, and 112.0 cm(3) (P = 0.38) and median MAT was 66.0, 90.0, and 81.0 cm(3) (P = 0.53) for non-significant, single vessel, and multi-vessel CAD, respectively. In age- and gender-adjusted analysis, only EAT was significantly associated with CAD (odds ratio [OR] 1.12 [95% confidence interval, 1.01-1.25] per 10 cm(3) increase in EAT; P = 0.04). This remained in multivariate-adjusted analysis (OR 1.21 [1.04-1.39]; P = 0.01)., Conclusions: In patients with known extra-cardiac arterial disease, CAD is correlated with EAT, but not with MAT. These results suggest that EAT has a local effect on coronary atherosclerosis, apart from the endocrine effect of visceral fat., (© 2013 The Obesity Society.)

Infection with human influenza virus leads to serious respiratory disease. Vaccination is the most common and effective prophylactic measure to prevent influenza. Influenza vaccine manufacturing and release is controlled by the correct determination of the potency-defining haemagglutinin (HA) content. This determination is historically done by single radial immunodiffusion (SRID), which utilizes a statistical slope-ratio model to estimate the actual HA content. In this paper we describe the development and qualification of a parallel line model for analysis of HA quantification by SRID in cell culture-derived whole virus final monovalent and trivalent influenza vaccines. We evaluated plate layout, sample randomization, and validity of data and statistical model. The parallel line model was shown to be robust and reproducible. The precision studies for HA content demonstrated 3.8-5.0% repeatability and 3.8%-7.9% intermediate precision. Furthermore, system suitability criteria were developed to guarantee long-term stability of this assay in a regulated production environment. SRID is fraught with methodological and logistical difficulties and the determination of the HA content requires the acceptance of new and modern release assays, but until that moment, the described parallel line model represents a significant and robust update for the current global influenza vaccine release assay., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Classical microbiological methods have nowadays unacceptably long cycle times. Rapid methods, available on the market for decades, are already applied within the clinical and food industry, but the implementation in pharmaceutical industry is hampered by for instance stringent regulations on validation and comparability with classical methods. Equivalence studies become less relevant when rapid methods are able to detect only one single microorganism. Directly testing this capability is currently impossible due to problems associated with preparing a spiked sample with low microbial counts. To be able to precisely estimate the limit of detection of rapid absence/presence tests, the method of the most probable limit is presented. It is based on three important elements; a relatively precise quantity of microorganisms, a non-serial dilution experiment and a statistical approach. For a set of microorganisms, a limit of detection of one was demonstrated using two different rapid methods., ((c) 2010 Elsevier B.V. All rights reserved.)