631 research outputs found

    Electing Representatives

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    Characteristic properties of FPTP systems

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    Repeated Cross-Sectional Randomized Response Data Taking Design Change and Self-Protective Responses into Account

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    Abstract. Randomized response (RR) is an interview technique that can be used to protect the privacy of respondents if sensitive questions are posed. This paper explains how to measure change in time if a binary RR question is posed at several time points. In cross-sectional research settings, new insights often gradually emerge. In our setting, a switch to another RR procedure necessitates the development of a trend model that estimates the effect of the covariate time if the dependent variable is measured by different RR designs. We also demonstrate that it is possible to deal with self-protective responses, thus accommodating our trend model with the latest developments in RR data analysis. Keywords: linear trend, longitudinal data, misclassification, randomized response, repeated cross-sections, self-protective responses Randomized response (RR) is an interview technique that can be used if sensitive questions are posed and respondents are reluctant to answer directly In addition to the RR setting, misclassification probabilities occur in several other fields of research. The one most closely related to RR is the postrandomization method (PRAM, Kooiman, Willenborg, & Gouweleeuw, 1997) that misclassifies values of categorical variables using a computerized process after the data are collected to protect the respondents' privacy. PRAM uses RR after the data collection. Misclassification also plays a role in medicine and epidemiology with the probabilities correctly classified as a case (sensitivity) or noncase (specificity), see This paper proposes a model to measure changes in time whenever RR is used to pose sensitive questions at several time points cross-sectionally. The model is illustrated with data from a Dutch repeated cross-sectional study on noncompliance to rules regarding social benefits. Data are collected every 2 years since 2000 and given that measures to prevent regulatory noncompliance are intensified during this period, the question arises as to whether the prevalence of regulatory noncompliance changes over the years and how the change can be modeled. Considering time a covariate, we propose a method to measure the effect of this covariate if the dependent variable is measured by RR. Several aspects of the cross-sectional study at hand make it impossible to use standard analysis methods and necessitate a new approach in the analysis of RR data to deal with research questions of this type. Firstly, the fact that RR variables represent misclassified responses on categorical variables precludes the use of, for example, the linear logit model (Agresti, 2002, p. 180), to test for a linear trend. Using the framework o

    Case finding of mild cognitive impairment and dementia and subsequent care; results of a cluster RCT in primary care

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    Purpose Despite a call for earlier diagnosis of dementia, the diagnostic yield of case finding and its impact on the mental health of patients and relatives are unclear. This study assessed the effect of a two-component intervention of case finding and subsequent care on these outcomes. Methods In a cluster RCT we assessed whether education of family physicians (FPs; trial stage 1) resulted in more mild cognitive impairment (MCI) and dementia diagnoses among older persons in whom FPs suspected cognitive decline and whether case finding by a practice nurse and the FP (trial stage 2) added to this number of diagnoses. In addition, we assessed mental health effects of case finding and subsequent care (trial stage 2). FPs of 15 primary care practices (PCPs = clusters) judged the cognitive status of all persons ≤ 65 years. The primary outcome, new MCI and dementia diagnoses by FPs after 12 months as indicated on a list, was assessed among all persons in whom FPs suspected cognitive impairment but without a formal diagnosis of dementia. The secondary outcome, mental health of patients and their relatives, was assessed among persons consenting to participate in trial stage 2. Trial stage 1 consisted of either intervention component 1: training FPs to diagnose MCI and dementia, or control: no training. Trial stage 2 consisted of either intervention component 2: case finding of MCI and dementia and care by a trained nurse and the FP, or control: care as usual. Results Seven PCPs were randomized to the intervention; eight to the control condition. MCI or dementia was diagnosed in 42.3 (138/326) of persons in the intervention, and in 30.5 (98/321) in the control group (estimated difference GEE: 10.8, OR: 1.51, 95-CI 0.60-3.76). Among patients and relatives who consented to stage 2 of the trial (n = 145; 25), there were no differences in mental health between the intervention and control group. Conclusions We found a non-significant increase in the number of new MCI diagnoses. As we cannot exclude a clinically relevant effect, a larger study is warranted to replicate ours. Trial Registration Nederlands Trial Register NTR3389 © 2016 van den Dungen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Classic infantile Pompe patients approaching adulthood: A cohort study on consequences for the brain

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    Aim: To examine the long-term consequences of glycogen storage in the central nervous system (CNS) for classic infantile Pompe disease using enzyme replacement therapy. Method: Using neuropsychological tests and brain magnetic resonance imaging (MRI), we prospectively assessed a cohort of 11 classic infantile Pompe patients aged up to 17 years. Results: From approximately age 2 years onwards, brain MRI showed involvement of the periventricular white matter and centrum semiovale. After 8 years of age, additional white-matter abnormalities occurred in the corpus callosum, internal and external capsule, and subcortical areas. From 11 years of age, white-matter abnormalities were also found in the brainstem. Although there seemed to be a characteristic pattern of involvement over time, there were considerable variations between patients, reflected by variations in neuropsychological development. Cognitive development ranged from stable and normal to declines that lead to intellectual disabilities. Interpretation: As treatment enables patients with classic infantile Pompe disease to reach adulthood, white-matter abnormalities are becoming increasingly evident, affecting the neuropsychological development. Therefore, we advise follow-up programs are expanded to capture CNS involvement in larger, international patient cohorts, to incorporate our findings in the counselling of parents before the start of treatment, and to include the brain as an additional target in the development of next-generation therapeutic strategies for classic infantile Pompe disease. What this paper adds: In our long-term survivors treated intravenously with enzyme replacement therapy, we found slowly progressive symmetric white-matter abnormalities. Cognitive development varied from stable and normal to declines towards intellectual disabilities

    Burden of illness of Pompe disease in patients only receiving supportive care

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    Background: Pompe disease is an orphan disease for which enzyme replacement therapy (ERT) recently became available. This study aims to estimate all relevant aspects of burden of illness-societal costs, use of home care and informal care, productivity losses, and losses in health-related quality of life (HRQoL)-for adult Pompe patients only receiving supportive care. Methods: We collected data on all relevant aspects of burden of illness via a questionnaire. We applied a societal perspective in calculating costs. The EQ-5D was used to estimate HRQoL. Results: Eighty adult patients (87% of the total Dutch adult Pompe population) completed a questionnaire. Disease severity ranged from mild to severe. Total annual costs were estimated at €22,475 (range €0-169,539) per adult Pompe patient. Patients on average received 8 h of home care and 19 h of informal care per week. Eighty-five percent of the patients received informal care from one or more caregivers; 40% had stopped working due to their disease; another 20% had reduced their working hours. HRQoL for Pompe patients who only received supportive care was estimated at 0.72, 17% lower than the Dutch population at large. Conclusions: Adult Pompe disease is associated with a considerable burden of illness at both the societal and patient levels. The disease leads to substantial costs and dependency on medical devices, home care, and informal care, and has a high impact on the patient's social network. In addition, patients are limited in their ability to work and have significantly reduced HRQoL

    Distal muscle weakness is a common and early feature in long-term enzyme-treated classic infantile Pompe patients

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    Background: Enzyme replacement therapy (ERT; alglucosidase alfa) has improved the prospects for patients with classic infantile Pompe disease considerably. However, over time we noticed that many of these children exhibit distal muscle weakness at an early age, which is in contrast to the primarily proximal and axial muscle weakness in patients with late-onset Pompe disease. This was reason to study the prevalence and severity of distal muscle weakness, and the sequence of muscle involvement over time in patients that had learned to walk under ERT. Methods: In this prospective, single-center cohort study, we studied 16 classic infantile patients. We used video recordings that were made during regular standardized assessments to investigate distal muscle function (active dorsiflexion of the feet during walking; ability to use a pincer grasp/actively extend the fingers) and proximal muscle function (standing up from a supine position; raising the arms above the head). Results: Median age at start of ERT was 3.2 months (0.1–5.8 months), median age at study end was 5.6 years (2.9– 18.2 years). Six patients (6/16, 38%) initially had no evident signs of distal muscle weakness and developed a gait with active dorsiflexion of the feet. The other 10 patients never exhibited active dorsiflexion of the feet during walking. At study-end two patients showed no loss of distal muscle function. A subset of five patients (5/16, 31%) developed also weakness of the hands, particularly of the extensors of the 3rd and 4th digit. Conclusions: We found that the majority (14/16, 88%) of patients who had learned to walk exhibited distal muscle weakness of the lower extremities, while a subset (5/16, 31%) also developed weakness of the hands. The distal muscle weakness was often more serious than, and preceded the development of, the proximal muscle weakness
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