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A major problem in the analysis of attrition of cohorts in studies on mental health problems is that data on those who do not participate at the outset of a study are largely unavailable. It is not known how underlying psychopathology affects the first stages of screening where non-response and selectivity are usually highest. This article presents results of one of the centres of the Netherlands Study of Depression and Anxiety (NESDA), a longitudinal study aimed at describing the long-term course and consequences of depression and anxiety disorders. The aim is to describe the different ways of attrition during the first NESDA-wave in a cohort of patients aged 18–65 years of the Registration Network Groningen and to analyse whether attrition is related to gender, age and psychopathology as recorded in general practice. The attrition of the study cohort (n = 8475) was highest during the first stages, eventually leading to a population of 169 patients only who participated in the full NESDA-programme. Probabilities of transition from one stage of the screening process to the next were regressed on selected background variables using binary logistic regression. Correlates of participation were being female and being older (>40). Psychopathology was an important variable in the formation of the initial sample cohort, but only had a weak influence on patient response to the screening questionnaire. Study design factors had a stronger impact on the changing composition of the cohort at each screening stage compared to patient factors. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Eradication of Helicobacter pylori prevents recurrence of peptic ulcer. In pharmacoeconomic analyses it is often presumed that after successful eradication no more gastrointestinal drugs are used. We investigated this presumed positive monetary effect using General Practitioners prescribing data, including information in diagnosis. From the RNG-database we identified patients with a H. pylori eradication in the years 1997–2000. H. pylori eradication was defined as a prescription of two antibiotics and one gastrointestinal drug on the same day. Patients were divided into a group with diagnosed ulcers and a group without diagnosed ulcers. Gastrointestinal drug costs were calculated for 4 months prior to eradication and 9–12 months post eradication. For comparison costs in all periods were expressed per patient per period. For statistical analysis the paired t-test was used. One hundred and two patients were eligible for evaluation. Of these patients 35 had a diagnosed ulcer and 67 had not. Generally the number of patients on gastrointestinal drugs decreased (61% prior vs. 33% post), however, the drug costs did not change (€33 prior vs. €34 post). Costs for proton pump inhibitors increased post eradication (€14 prior vs. €28 post). The ulcer and nonulcer group showed similar results. Helicobacter pylori eradication is thought to be cost effective, however, we did not find a decrease in costs for all gastrointestinal drugs. There may be a great pharmacoeconomical advantage when it is possible to predict which patients are more likely to ‘fail’ eradication therapy. [ABSTRACT FROM AUTHOR]