Do childhood and adult socioeconomic circumstances influence health and physical function in middle-age?

This study examines the joint and separate contribution of social class in early and adult life to differences in health and physical function in middle-aged men. We use data from the Metropolit project which includes men born in 1953 in Copenhagen and a study of middle-aged Danish twins (MADT). In total 6292 Metropolit participants in a follow-up survey on health in 2004 were included in the study together with 2198 male twins of which 1294 were part of a male twin pair (N=647 pairs). Logistic regression was used to investigate the association between social class in early and adult life, respectively and health in midlife, measured as limitations in running 100 m, poor dental status, poor self-rated health, and fatigue. In both datasets, men with low childhood or adult social class had a higher risk of being unable to run 100 m, having poor dental status, having poor self-rated health and fatigue than men from the highest social classes. When childhood and adult social class were mutually adjusted, the estimates for both measures were attenuated. Adjustment for living without a partner, body mass index (BMI) and smoking in midlife, which were also related to the four outcomes, had marginal effects on the estimates for childhood social class, but attenuated the effect of adult social class somewhat. Among male twin pairs discordant on adult social class, the twin in the lowest class seemed to be unable to run 100 m, rate own health poorer and being fatigued more often than the high class co-twin, while there seemed to be no twin pair difference in dental status. This suggests that the associations of adult social class with functional limitations, poor self-rated health and fatigue may partly be due to causal effects related to adult social class exposures, while social class differences in dental status might be consistent with an effect of factors mainly operating early in life.