Comparative study of two birth cohorts: did the explanatory role of behavioural, social and psychological factors in educational inequalities in mortality change over time?

Objectives: To investigate the contribution of behavioural, social and psychological factors to inequalities in mortality by educational level between birth cohorts.

Design: Cohort-sequential design.

Setting: Two population-based studies in the Netherlands: the Longitudinal Aging Study Amsterdam (LASA) and the Doetinchem Cohort Study (DCS).

Participants: Data from the LASA included 1990 individuals with birth years 1928-1937 (cohort 1) and 1938-1947 (cohort 2) and, for replication, data from the DCS included 2732 individuals with birth years 1929-1941 (cohort 1) and 1939-1951 (cohort 2).

Methods: Years of education, 15-year mortality, lifestyle factors, social factors and psychological factors were modelled using multiple-group accelerated failure time models based on structural equation modelling to compare indirect effects between cohorts.

Results: Both studies showed similar educational inequalities, with higher mortality among those with lower education. The indirect effects of education via smoking (LASA: difference in survival time ratio (TR)=1.0018, 95% CI 1.0000 to 1.0155, DCS: TR=1.0051, 95% CI 1.0000 to 1.0183), physical activity (LASA: TR=1.0056, 95% CI 1.00009 to 1.0132) and alcohol use (LASA: TR=1.0275, 95% CI 1.0033 to 1.0194) on mortality were stronger in cohort 2 than in cohort 1. In contrast to the other effects, alcohol use was the only factor that was associated positively with education and survival time, which effect increased in the most recent cohort. Emotional support, network size and cognitive functioning showed no difference between cohorts.

Conclusions: Smoking, physical activity and alcohol use contributed more to educational inequalities in mortality in recent cohorts. Hence, in addition to tackling fundamental social causes of inequality, policies focusing on intermediary mechanisms such as lifestyle need to adapt their targets to those that prove to be most important within a given time frame.