A population-based study of nearly 15 000 observations among Swedish women and men during 1973-2003.

Objectives: Global self-rated health (SRH) has become extensively used as an outcome measure in population health surveillance. The aim of this study was to analyse the effects of age and secular trend (year of investigation) on SRH. Design: Prospective cohort study, using population-based data from eight ongoing cohort studies, with sampling performed between 1973 and 2003. Setting: Sweden. Participants: 11 880 women and men, aged 25-99 years, providing 14 470 observations. Primary outcome measure: Global SRH. Results: In multiple ordinal logistic regression analyses, adjusted for the effects of covariates, there were independent effects of age (p<0.0001) and of year of investigation (p<0.0001) on SRH. In women the association was linear, showing lower levels of SRH with increased age, and more recent year of investigation. In men the association was curvilinear, and thus more complex. The final model explained 76.2% of the SRH variance in women and 74.5% of the variance in men. Conclusions: SRH was strongly and inversely associated with age in both sexes, after adjustment for other outcome-affecting variables. There was a strongly significant effect of year of investigation indicating a change in SRH, in women towards lower levels over calendar time, in men with fluctuations across time.