@article{ref1,
title="Selection effects in psychiatric epidemiology : A 14-year prospective study of the Hopkins Symptom Check List-25 as a predictor of mortality in the Norwegian general population",
journal="Social psychiatry and psychiatric epidemiology",
year="2009",
author="Nygård, Jan F. and Klungsøyr, O and Sandanger, Inger and Svensson, Elisabeth",
volume="44",
number="10",
pages="881-886",
abstract="BACKGROUND: Inconsistent findings in studies examining the association between mental health problems and mortality have suggested study design as a source of discrepancy. This study investigates if selection bias is introduced by an extensive personal interview, recruiting a healthier population, and furthermore examines the association between mental distress and mortality. METHOD: The OsLof study consists of a random population-based sample of 2,014 persons above 18 years that participated in an interview in 1989, including the Hopkins Symptom Check List-25 (HSCL-25). A second material was drawn as an approximate 1% sample of the Norwegian population (N = 31.907). Both samples were followed up until 2003, emigration or death. Hazard rates were estimated by Cox regression and piecewise exponential survival regression. RESULTS: Mortality rates were similar regardless of HSCL, and lower than in the 1% population sample, in the first 2 years of follow-up. A higher mortality rate in those with HSCL >/= 1.75 appeared after 8 years of follow-up, and after 12 years the mortality rate was 1.57 times higher than in the population sample. CONCLUSION: Studies of predictors ought to have a long follow-up, as several years might pass before differences in mortality are revealed. Due to selection effects, short follow-up might lead to erroneously believing predictors to be protective. This study was consistent with other studies with long follow-up, showing higher mortality associated with mental distress.<p /> <p>Language: en</p>",
language="en",
issn="0933-7954",
doi="10.1007/s00127-009-0010-z",
url="http://dx.doi.org/10.1007/s00127-009-0010-z"
}