Age, time, and cohort effects on functional status and self-rated health in elderly men.

Abstract

This study investigated age-related changes in functional status and self-rated health in elderly men, taking into account changes over time and differences between birth cohorts. The Zutphen Elderly Study is a longitudinal study of men born in the Netherlands between 1900 and 1920. Functional status and self-rated health were measured in 513 men in 1990, in 381 men in 1993, and in 340 men in 1995. Age, time, and cohort effects were analyzed in a mixed longitudinal model. Longitudinal analyses showed that during 5 years of follow-up, the proportion of men without disabilities decreased from 53% to 39%, whereas the percentage who rated themselves as healthy decreased from 50% to 35%. Cross-sectional analyses confirmed changes in functional status, suggesting an age effect. Time-series analyses confirmed changes in self-rated health, suggesting a time effect. No birth-cohort effects were found. Functional status deteriorates with age, whereas self-rated health is not related to age in men aged 70 years and older. The observed 5-year decline in self-rated health seemed to be due to a secular trend.