The shape of health to come: prospective study of the determinants of 30-year health trajectories in the Alameda County Study

BACKGROUND: Considerable evidence now exists indicating that incidence and progression of disease and disability are associated with socio-economic, behavioural, demographic and psychosocial factors. The emerging life course perspective suggests that these factors might be associated with not just the incidence of disease and death, but also trajectories of health over decades. METHODS: Prospective study of a representative, population-based cohort studied on four occasions over 30 years. Trajectories of health over this period, combining self-rated health and date of death, were related to behavioural, psychosocial and socio-economic risk factors. RESULTS: Trajectories of health were associated with behavioural, socioeconomic, and psychosocial risk factors, the strongest predictors being household income and physical activity. Those with an income 1 SD above the mean were approximately 25% more likely to die having previously consistently reported excellent health (Men: relative risk (RR) = 1.27, 95% CI = 1.10-1.46; Women: RR = 1.25, 95% CI = 1.06-1.47), were more likely to remain 'Alive in Excellent Health' (Men: RR = 1.35, 95% CI = 1.21-1.51; Women: RR = 1.30, 95% CI = 1.19-1.43) and were less likely to have shown an 'Unremitting Decline' (Men: RR = 0.72, 95% CI = 0.49-1.05; Women: RR = 0.71, 95% CI = 0.48-1.04). Those with low physical activity were approximately 50% less likely to die having consistently reported excellent health (Men: RR = 0.54, 95% CI = 0.39-0.76; Women: RR = 0.48, 95% CI = 0.33-0.71), and were five-times more likely to show an 'Unremitting Decline' (Men: RR = 5.05, 95% CI = 1.75-14.56; Women: RR = 5.00, 95% CI = 1.48-16.92). They were also less likely to be 'Alive in Excellent Health' (Men: RR = 0.41, 95% CI = 0.29-0.57; Women: RR = 0.44, 95% CI = 0.33-0.57). CONCLUSIONS: The burden of illness associated with behavioural, socio-economic and psychosocial risk factors extends beyond shortening of life to poorer trajectories of health over decades.