110 resultados para Informative drop-out

em Université de Lausanne, Switzerland


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This study examines the importance of change in characteristics and circumstances of households and household members for contact and cooperation patterns. The literature suggests that there might be an underrepresentation of change in panel studies, because respondents facing more changes would be more likely to drop out. We approach this problem by analysing whether previous changes are predictive of later attrition or temporary drop-out, using eleven waves of the Swiss Household Panel (1999-2009). Our analyses support previous findings to some extent. Changes in household composition, employment status and social involvement as well as moving are associated mainly with attrition and less with temporary drop-out. These changes affect obtaining cooperation rather than obtaining contact, and tend to increase attrition.

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This study examines the importance of change in characteristics and circumstances ofhouseholds and household members for contact and cooperation patterns. The literaturesuggests that there might be an underrepresentation of change in panel studies, becauserespondents facing more changes would be more likely to drop out. We approach this problemby analysing whether previous changes are predictive of later attrition or temporary drop-out,using eleven waves of the Swiss Household Panel (1999-2009). Our analyses supportprevious findings to some extent. Changes in household composition, employment status andsocial involvement as well as moving are associated mainly with attrition and less withtemporary drop-out. These changes affect obtaining cooperation rather than obtaining contact,and tend to increase attrition.

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What genotype should the scientist specify for conducting a database search to try to find the source of a low-template-DNA (lt-DNA) trace? When the scientist answers this question, he or she makes a decision. Here, we approach this decision problem from a normative point of view by defining a decision-theoretic framework for answering this question for one locus. This framework combines the probability distribution describing the uncertainty over the trace's donor's possible genotypes with a loss function describing the scientist's preferences concerning false exclusions and false inclusions that may result from the database search. According to this approach, the scientist should choose the genotype designation that minimizes the expected loss. To illustrate the results produced by this approach, we apply it to two hypothetical cases: (1) the case of observing one peak for allele xi on a single electropherogram, and (2) the case of observing one peak for allele xi on one replicate, and a pair of peaks for alleles xi and xj, i ≠ j, on a second replicate. Given that the probabilities of allele drop-out are defined as functions of the observed peak heights, the threshold values marking the turning points when the scientist should switch from one designation to another are derived in terms of the observed peak heights. For each case, sensitivity analyses show the impact of the model's parameters on these threshold values. The results support the conclusion that the procedure should not focus on a single threshold value for making this decision for all alleles, all loci and in all laboratories.

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QUESTIONS UNDER STUDY: the main purpose of this longitudinal study was to determine the impact of risky single occasion drinking (RSOD) frequency on alcohol dependence and drinking consequences reported 15 months later. METHODS: As a baseline sample, 5,990 young men were assessed on their drinking habits including the frequency of RSOD. Of them, 5,196 were reassessed at follow-up 15 months later on RSOD frequency, alcohol dependence and alcohol related consequences in thze interceding year. Drop out biases were investigated. RESULTS: Around 45% of the baseline participants reported regular RSOD (every month or more frequently). Despite the fact that RSOD distribution was generally stable during the initial sample, 47.4% reported a variation of their RSOD frequency 15 months later. Around 25% of the sample reported reduced RSOD frequency. Nonetheless, occasional RS drinkers were more likely to become regular (monthly) RSO drinkers at follow up. Daily and weekly RSOD were associated with high proportions of alcohol dependence and detrimental consequences of drinking. Surprisingly, abstainers at baseline were more likely to be at risk of alcohol dependence and consequences at follow up than non-RSO drinkers. CONCLUSIONS: Despite the fact that alcohol abstinence is logically the best way to avoid the detrimental consequences of alcohol drinking, abstainers at baseline reported as many problems due to alcohol use at follow up as occasional or monthly RSO drinkers. The few participants who had become RSO drinkers during the follow up period were indeed likely to engage in detrimental behaviour. Non-RSO drinkers had the fewest problems due to alcohol use. This substantiates the early occurrence of drinking consequences among inexperienced RSO drinkers.

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Epidemiological data indicate that 75% of subjects with major psychiatric disorders have their onset in the age range of 17-24 years. An estimated 35-50% of college and university students drop out prematurely due to insufficient coping skills under chronic stress, while 85% of students receiving a psychiatric diagnosis withdraw from college/university prior to the completion of their education. In this study we aimed at developing standardized means for identifying students with insufficient coping skills under chronic stress and at risk for mental health problems. A sample of 1,217 college students from 3 different sites in the U.S. and Switzerland completed 2 self-report questionnaires: the Coping Strategies Inventory "COPE" and the Zurich Health Questionnaire "ZHQ" which assesses "regular exercises", "consumption behavior", "impaired physical health", "psychosomatic disturbances", and "impaired mental health". The data were subjected to structure analyses by means of a Neural Network approach. We found 2 highly stable and reproducible COPE scales that explained the observed inter-individual variation in coping behavior sufficiently well and in a socio-culturally independent way. The scales reflected basic coping behavior in terms of "activity-passivity" and "defeatism-resilience", and in the sense of stable, socio-culturally independent personality traits. Correlation analyses carried out for external validation revealed a close relationship between high scores on the defeatism scale and impaired physical and mental health. This underlined the role of insufficient coping behavior as a risk factor for physical and mental health problems. The combined COPE and ZHQ instruments appear to constitute powerful screening tools for insufficient coping skills under chronic stress and for risks of mental health problems.

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Objectives This article presents a psychological approach to substance use in sport using a dynamic and situated activity framework. The aim was to analyze the various relationships between activity and the consumption of substances during the sporting life course of athletes who recognized doping violation. Design Data were collected from secondary sources and biographical and self-confrontational interviews to build traces of the past activity. Method Twelve doping athletes or those admitting to having used banned substances volunteered to participate. The data were coded and compared to identify typical activities and their intrinsic dynamics. Results Six activities were identified: "Agree to use," "Drop out of a non-viable state," Return to a former state," "Prevent a potential deficiency," "Maintain an acquired state," and "Balance the sporting life with substance use," comprising 11 patterns. Conclusions The athletes' activity embedded substance use in reciprocal relationships that consisted of freezing, exploring and exploiting fields of possible actions created and offered by the situation dynamics. Recommendations for situated and dynamic prevention are provided.

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BACKGROUND/AIMS: Treatment of chronic HCV infection has become a priority in HIV+ patients, given the faster progression to end-stage liver disease. The primary endpoint of this study was to evaluate and compare antiviral efficacy of Peginterferon alpha 2a plus ribavirin in HIV-HCV co-infected and HCV mono-infected patients, and to examine whether 6 months of therapy would have the same efficacy in HIV patients with favourable genotypes 2 and 3 as in mono-infected patients, to minimise HCV-therapy-related toxicities. Secondary endpoints were to evaluate predictors of sustained virological response (SVR) and frequency of side-effects. METHODS: Patients with genotypes 1 and 4 were treated for 48 weeks with Pegasys 180 microg/week plus Copegus 1000-1200 mg/day according to body weight; patients with genotypes 2 and 3 for 24 weeks with Pegasys 180 microg/week plus Copegus 800 mg/day. RESULTS: 132 patients were enrolled in the study: 85 HCV mono-infected (38: genotypes 1 and 4; 47: genotypes 2 and 3), 47 HIV-HCV co-infected patients (23: genotypes 1 and 4; 24: genotypes 2 and 3). In an intention-to-treat analysis, SVR for genotypes 1 and 4 was observed in 58% of HCV mono-infected and in 13% of HIV-HCV co-infected patients (P = 0.001). For genotypes 2 and 3, SVR was observed in 70% of HCV mono-infected and in 67% of HIV-HCV co-infected patients (P = 0.973). Undetectable HCV-RNA at week 4 had a positive predictive value for SVR for mono-infected patients with genotypes 1 and 4 of 0.78 (95% CI: 0.54-0.93) and of 0.81 (95% CI: 0.64-0.92) for genotypes 2 and 3. For co-infected patients with genotypes 2 and 3, the positive predictive value of SVR of undetectable HCV-RNA at week 4 was 0.76 (95%CI, 0.50-0.93). Study not completed by 22 patients (36%): genotypes 1 and 4 and by 12 patients (17%): genotypes 2 and 3. CONCLUSION: Genotypes 2 or 3 predict the likelihood of SVR in HCV mono-infected and in HIV-HCV co-infected patients. A 6-month treatment with Peginterferon alpha 2a plus ribavirin has the same efficacy in HIV-HCV co-infected patients with genotypes 2 and 3 as in mono-infected patients. HCV-RNA negativity at 4 weeks has a positive predictive value for SVR. Aggressive treatment of adverse effects to avoid dose reduction, consent withdrawal or drop-out is crucial to increase the rate of SVR, especially when duration of treatment is 48 weeks. Sixty-one percent of HIV-HCV co-infected patients with genotypes 1 and 4 did not complete the study against 4% with genotypes 2 and 3.

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BACKGROUND: Antiretroviral therapy (ART) decreases morbidity and mortality in HIV-infected patients but is associated with considerable adverse events (AEs). METHODS: We examined the effect of AEs to ART on mortality, treatment modifications and drop-out in the Swiss HIV Cohort Study. A cross-sectional evaluation of prevalence of 13 clinical and 11 laboratory parameters was performed in 1999 in 1,078 patients on ART. AEs were defined as abnormalities probably or certainly related to ART. A score including the number and severity of AEs was defined. The subsequent progression to death, drop-out and treatment modification due to intolerance were evaluated according to the baseline AE score and characteristics of individual AEs. RESULTS: Of the 1,078 patients, laboratory AEs were reported in 23% and clinical AEs in 45%. During a median follow up of 5.9 years, laboratory AEs were associated with higher mortality with an adjusted hazard ratio (HR) of 1.3 (95% confidence interval [CI] 1.2-1.5; P < 0.001) per score point. For clinical AEs no significant association with increased mortality was found. In contrast, an increasing score for clinical AEs (HR 1.11,95% CI 1.04-1.18; P = 0.002), but not for laboratory AEs (HR 1.07, 95% CI 0.97-1.17; P = 0.17), was associated with antiretroviral treatment modification. AEs were not associated with a higher drop-out rate. CONCLUSIONS: The burden of laboratory AEs to antiretroviral drugs is associated with a higher mortality. Physicians seem to change treatments to relieve clinical symptoms, while accepting laboratory AEs. Minimizing laboratory drug toxicity seems warranted and its influence on survival should be further evaluated.

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Aims Perfusion-cardiac magnetic resonance (CMR) has emerged as a potential alternative to single-photon emission computed tomography (SPECT) to assess myocardial ischaemia non-invasively. The goal was to compare the diagnostic performance of perfusion-CMR and SPECT for the detection of coronary artery disease (CAD) using conventional X-ray coronary angiography (CXA) as the reference standard. Methods and results In this multivendor trial, 533 patients, eligible for CXA or SPECT, were enrolled in 33 centres (USA and Europe) with 515 patients receiving MR contrast medium. Single-photon emission computed tomography and CXA were performed within 4 weeks before or after CMR in all patients. The prevalence of CAD in the sample was 49%. Drop-out rates for CMR and SPECT were 5.6 and 3.7%, respectively (P = 0.21). The primary endpoint was non-inferiority of CMR vs. SPECT for both sensitivity and specificity for the detection of CAD. Readers were blinded vs. clinical data, CXA, and imaging results. As a secondary endpoint, the safety profile of the CMR examination was evaluated. For CMR and SPECT, the sensitivity scores were 0.67 and 0.59, respectively, with the lower confidence level for the difference of +0.02, indicating superiority of CMR over SPECT. The specificity scores for CMR and SPECT were 0.61 and 0.72, respectively (lower confidence level for the difference: -0.17), indicating inferiority of CMR vs. SPECT. No severe adverse events occurred in the 515 patients. Conclusion In this large multicentre, multivendor study, the sensitivity of perfusion-CMR to detect CAD was superior to SPECT, while its specificity was inferior to SPECT. Cardiac magnetic resonance is a safe alternative to SPECT to detect perfusion deficits in CAD.

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In studies of the natural history of HIV-1 infection, the time scale of primary interest is the time since infection. Unfortunately, this time is very often unknown for HIV infection and using the follow-up time instead of the time since infection is likely to provide biased results because of onset confounding. Laboratory markers such as the CD4 T-cell count carry important information concerning disease progression and can be used to predict the unknown date of infection. Previous work on this topic has made use of only one CD4 measurement or based the imputation on incident patients only. However, because of considerable intrinsic variability in CD4 levels and because incident cases are different from prevalent cases, back calculation based on only one CD4 determination per person or on characteristics of the incident sub-cohort may provide unreliable results. Therefore, we propose a methodology based on the repeated individual CD4 T-cells marker measurements that use both incident and prevalent cases to impute the unknown date of infection. Our approach uses joint modelling of the time since infection, the CD4 time path and the drop-out process. This methodology has been applied to estimate the CD4 slope and impute the unknown date of infection in HIV patients from the Swiss HIV Cohort Study. A procedure based on the comparison of different slope estimates is proposed to assess the goodness of fit of the imputation. Results of simulation studies indicated that the imputation procedure worked well, despite the intrinsic high volatility of the CD4 marker.

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ABSTRACT: BACKGROUND: Perfusion-cardiovascular magnetic resonance (CMR) is generally accepted as an alternative to SPECT to assess myocardial ischemia non-invasively. However its performance vs gated-SPECT and in sub-populations is not fully established. The goal was to compare in a multicenter setting the diagnostic performance of perfusion-CMR and gated-SPECT for the detection of CAD in various populations using conventional x-ray coronary angiography (CXA) as the standard of reference. METHODS: In 33 centers (in US and Europe) 533 patients, eligible for CXA or SPECT, were enrolled in this multivendor trial. SPECT and CXA were performed within 4 weeks before or after CMR in all patients. Prevalence of CAD in the sample was 49% and 515 patients received MR contrast medium. Drop-out rates for CMR and SPECT were 5.6% and 3.7%, respectively (ns). The study was powered for the primary endpoint of non-inferiority of CMR vs SPECT for both, sensitivity and specificity for the detection of CAD (using a single-threshold reading), the results for the primary endpoint were reported elsewhere. In this article secondary endpoints are presented, i.e. the diagnostic performance of CMR versus SPECT in subpopulations such as multi-vessel disease (MVD), in men, in women, and in patients without prior myocardial infarction (MI). For diagnostic performance assessment the area under the receiver-operator-characteristics-curve (AUC) was calculated. Readers were blinded versus clinical data, CXA, and imaging results. RESULTS: The diagnostic performance (= area under ROC = AUC) of CMR was superior to SPECT (p = 0.0004, n = 425) and to gated-SPECT (p = 0.018, n = 253). CMR performed better than SPECT in MVD (p = 0.003 vs all SPECT, p = 0.04 vs gated-SPECT), in men (p = 0.004, n = 313) and in women (p = 0.03, n = 112) as well as in the non-infarct patients (p = 0.005, n = 186 in 1-3 vessel disease and p = 0.015, n = 140 in MVD). CONCLUSION: In this large multicenter, multivendor study the diagnostic performance of perfusion-CMR to detect CAD was superior to perfusion SPECT in the entire population and in sub-groups. Perfusion-CMR can be recommended as an alternative for SPECT imaging. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT00977093.

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OBJECTIVES: This is the first meta-analysis on the efficacy of composite resin restorations in anterior teeth. The objective of the present meta-analysis was to verify whether specific material classes, tooth conditioning methods and operational procedures influence the result for Class III and Class IV restorations. MATERIAL AND METHODS: The database SCOPUS and PubMed were searched for clinical trials on anterior resin composites without restricting the search to the year of publication. The inclusion criteria were: (1) prospective clinical trial with at least 2 years of observation; (2) minimal number of restorations at last recall=20; (3) report on drop-out rate; (4) report of operative technique and materials used in the trial, and (5) utilization of Ryge or modified Ryge evaluation criteria. For the statistical analysis, a linear mixed model was used with random effects to account for the heterogeneity between the studies. p-Values smaller than 0.05 were considered to be significant. RESULTS: Of the 84 clinical trials, 21 studies met the inclusion criteria, 14 of them for Class III restorations, 6 for Class IV restorations and 1 for closure of diastemata; the latter was included in the Class IV group. Twelve of the 21 studies started before 1991 and 18 before 2001. The estimated median overall success rate (without replacement) after 10 years for Class III composite resin restorations was 95% and for Class IV restorations 90%. The main reason for the replacement of Class IV restorations was bulk fractures, which occurred significantly more frequently with microfilled composites than with hybrid and macrofilled composites. Caries adjacent to restorations was infrequent in most studies and accounted only for about 2.5% of all replaced restorations after 10 years irrespective of the cavity class. Class III restorations with glass ionomer derivates suffered significantly more loss of anatomical form than did fillings with other types of material. When the enamel was acid-etched and no bonding agent was applied, significantly more restorations showed marginal staining and detectable margins compared to enamel etching with enamel bonding or the total etch technique; fillings with self-etching systems were in between of these two outcome variables. Bevelling of the enamel was associated with a significantly reduced deterioration of the anatomical form compared to no bevelling but not with less marginal staining or less detectable margins. The type of isolation (absolute/relative) had a statistically significant influence on marginal caries which, however, might be a random finding.

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BACKGROUND & AIMS: The landscape of HCV treatments is changing dramatically. At the beginning of this new era, we highlight the challenges for HCV therapy by assessing the long-term epidemiological trends in treatment uptake, efficacy and mortality among HIV/HCV-coinfected people since the availability of HCV therapy. METHODS: We included all SHCS participants with detectable HCV RNA between 2001 and 2013. To identify predictors for treatment uptake uni- and multivariable Poisson regression models were applied. We further used survival analyses with Kaplan-Meier curves and Cox regression with drop-out as competing risk. RESULTS: Of 12,401 participants 2107 (17%) were HCV RNA positive. Of those, 636 (30%) started treatment with an incidence of 5.8/100 person years (PY) (95% CI 5.3-6.2). Sustained virological response (SVR) with pegylated interferon/ribavirin was achieved in 50% of treated patients, representing 15% of all participants with replicating HCV-infection. 344 of 2107 (16%) HCV RNA positive persons died, 59% from extrahepatic causes. Mortality/100 PY was 2.9 (95% CI 2.6-3.2) in untreated patients, 1.3 (1.0-1.8) in those treated with failure, and 0.6 (0.4-1.0) in patients with SVR. In 2013, 869/2107 (41%) participants remained HCV RNA positive. CONCLUSIONS: Over the last 13years HCV treatment uptake was low and by the end of 2013, a large number of persons remain to be treated. Mortality was high, particularly in untreated patients, and mainly due to non-liver-related causes. Accordingly, in HIV/HCV-coinfected patients, integrative care including the diagnosis and therapy of somatic and psychiatric disorders is important to achieve mortality rates similar to HIV-monoinfected patients.

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Technical developments have made it possible to analyze very low amounts of DNA. This has many advantages, but the drawback of this technological progress is that interpretation of the results becomes increasingly complex: the number of mixed DNA profiles increased relatively to single source DNA profiles and stochastic effects in the DNA profile, such as drop-in and drop-out, are more frequently observed. Moreover, the relevance of low template DNA material regarding the activities alleged is not as straightforward as it was a few years ago, when for example large quantities of blood were recovered. The possibility of secondary and tertiary transfer is now becoming an issue. The purpose of this research is twofold: first, to study the transfer of DNA from the handler and secondly, to observe if handlers would transfer DNA from persons closely connected to them. We chose to mimic cases where the offender would attack a person with a knife. As a first approach, we envisaged that the defense would not give an alternative explanation for the origin of the DNA. In our transfer experiments (4 donors, 16 experiments each, 64 traces), 3% of the traces were single DNA profiles. Most of the time, the DNA profile of the person handling the knife was present as the major profile: in 83% of the traces the major contributor profile corresponded to the stabber's DNA profile (in single stains and mixtures). Mixture with no clear major/minor fraction (12%) were observed. 5% of the traces were considered of insufficient quality (more than 3 contributors, presence of a few minor peaks). In that case, we considered that the stabber's DNA was absent. In our experiments, no traces allowed excluding the stabber, however it must be noted that precautions were taken to minimize background DNA as knives were cleaned before the experiments. DNA profiles of the stabber's colleagues were not observed. We hope that this study will allow for a better understanding of the transfer mechanism and of how to assess and describe results given activity level propositions. In this preliminary research, we have focused on the transfer of DNA on the hand of the person. Besides, more research is needed to assign the probability of the results given an alternative activity proposed by the defense, for instance when the source of the DNA is not contested, but that the activities are.

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Background: T reatment o f chronic hepatitis C i s evolving, a nd direct acting antivirals ( DAAs) are now a dded to p egylated interferon-α ( Peg- INF-α) and ribavirin (RBV) for the treatment o f hepatitis C v irus ( HCV) genotype 1 infection. DAAs c ause d ifferent side effects and can even worsen RBV induced hemolytic anemia. T herefore, identifying host genetic d eterminants of R BV bioavailability and therapeutic e fficacy will remain crucial for individualized treatment. Recent d ata showed associations between R BV induced h emolytic anemia and genetic polymorphisms o f concentrative nucleoside transporters s uch as C NT3 (SLC28A3) and i nosine t riphosphatase (ITPA). T o analyze t he association of genetic variants of SLC28 transporters and ITPA with RBV induced hemolytic anemia and treatment o utcome. Methods: I n our study, 173 patients f rom t he S wiss Hepatitis C C ohort Study and 2 2 patients from Swiss Association for the Study of the Liver study 24 (61% HCV g enotype 1, 3 9% genotypes 2 o r 3) were analyzed for SLC28A2 single nucleotide p olymorphism (SNP) rs11854484, SLC28A3 rs56350726 and SLC28A3 rs10868138 as well as ITPA SNPs rs1127354 and rs7270101. RBV serum levels during treatment were measured in 49 patients. Results: SLC28A2 r s11854484 genotype TT was associated with significantly higher dosage- and body weight-adjusted RBV levels as compared to genotypes TC and CC (p=0.04 and p=0.02 at weeks 4 and 8, respectively). ITPA SNPs rs1127354 and rs7270101 were associated with h emolytic a nemia both in genotype as w ell as i n allelic a nalyses. SLC28A3 rs56350726 genotype TT (vs. AT/AA, RR=2.1; 95% CI 1.1-4.1) as well as the T allele (vs. A; RR=1.8, 95% CI 1.1-3.2) were associated with increased SVR rates. The combined analysis of overall ITPA activity and SLC28 v ariants together revealed n o significant a dditive effects on either treatment-related anemia or SVR. Conclusions: T he newly identified association between RBV serum levels a nd SLC28A2 rs11854484 genotype as well as the replicated association of ITPA and SLC28A3 g enetic p olymorphisms w ith RBV induced hemolytic anemia and treatment r esponse underpin the need for further studies on host genetic d eterminants of R BV bioavailability and therapeutic e fficacy f or individualized treatment of chronic hepatitis C.