Dynamics of health behaviours and socioeconomic differences in mortality in the USA

Background: To measure the explanatory role of behavioural factors to educational and income disparities in mortality among US adults (ages 25+). Methods: Data were from four waves of the American Changing Lives Study (N=3617). There were 1832 deaths between 1986 and 2011. Smoking, physical activity, alcohol and body mass index were examined. Results: Those with 0-11 years of schooling had an 88% (95% CI 48% to 139%) increased risk of dying compared to those with 16+years of schooling. Behavioural factors explained 41% (95% CI 26% to 55%) and 50% (95% CI 30% to 70%) of this excess in models that treated behavioural factors as fixed (single point in time) and time varying (repeated), respectively. The lowest income group (bottom 20th centile) had a 209% (95% CI 172% to 256%) increased risk of dying relative to the highest income group (top 40th centile). Behavioural factors explained 24% (fixed, 95% CI 13% to 35%) and 39% (repeated, 95% CI 22% to 56%) of this difference. Analyses of deaths by causes indicated that behavioural factors were more consequential to disparities in cardiovascular mortality, explaining up to 83% of educational differences, compared to cancer and other death causes. Conclusions: Behavioural factors are one of a number of factors which explain socioeconomic mortality disparities, but their estimated explanatory role depends on a number of parameters including the socioeconomic status measure examined, the cause of death and age. In this nationally representative sample, findings based on repeated measures did not warrant a re-evaluation of earlier estimates.