Health Behaviors More Important than Socioeconomic Status

Many studies have reported that socioeconomic status is a predictor of morbidity and mortality. Now, a large-scale, longitudinal study asserts that the association may be more related to health behaviors than socioeconomic status. The study, published in the Journal of the American Medical Association (JAMA), reports that assessment of health behaviors over time lessens the association between socioeconomic status and mortality.

The present study uses data from the Whitehall II study — a long-term follow-up study of more than 10,000 British civil servants aged 35 to 55 years. Data was collected from 1985 until April 2009. Of the 9590 men and women included in the JAMA evaluation, there were 654 deaths during the follow-up period. To assess the contribution that health behaviors have towards the association between socioeconomic status and mortality, the authors used civil service employment grade as an indicator of socioeconomic status, and measured health behaviors — smoking, alcohol consumption, diet, and physical activity — at 4 points during follow-up.

Overall, the risk of all-cause mortality was 1.6 times higher in the lowest socioeconomic status group versus the highest, amounting to 1.94 deaths per 1000 person-years. However, this association between socioeconomic status and death was weakened when adjusted for health behaviors: 42% weaker when only baseline health behaviors were considered and 72% weaker when time-dependent health behaviors were considered. Adjusting for health behaviors also decreased the association between socioeconomic status and specific causes of death. When assessed only at baseline, the association was weakened by 29% for cardiovascular mortality, versus 45% when health behaviors were assessed over time. Similarly, the association between socioeconomic status and noncardiovascular and noncancer mortality decreased by 61% when health behaviors were analyzed at baseline versus 94% when considered over time.

These differences in associations of mortality reflect the effect of lifestyle changes on all-cause mortality. Likewise, the effect of diet was increased from 7% to 17% when health behaviors were considered at baseline versus over time, respectively. The corresponding explanatory power of physical activity on all-cause mortality increased from 5% to 21%, and that of alcohol consumption increased from 3% to 12%. The role of smoking did not change the association between socioeconomic status and all-cause mortality.

The prevalence of unhealthy behaviors is high among lower socioeconomic groups, and they contribute to increased morbidity and mortality. Until this study, most evaluations of socioeconomic status and morbidity and mortality only assess health behaviors at baseline; this study emphasizes the effect of changing health behaviors on mortality, regardless of socioeconomic status. Health behaviors likely play a larger role than socioeconomic status in all-cause mortality, according to the authors.

However, inequalities in health behaviors, policies and interventions exist, which are correlated to socioeconomic status. So, which comes first? Are health behaviors socially patterned and predetermined , leading  to maintenance of a certain socioeconomic status? Or, do inadequate health policies and interventions among low socioeconomic groups lead to poor health behaviors? Does simply the stress associated with having low socioeconomic status influence poor health behaviors? Many recent studies describe associations between low socioeconomic status and higher all-cause mortality, as well as specific cancer-related deaths, kidney transplant failure and mortality, and heart transplant rejection, but fail to identify the root of the association.

Since the current analysis of the association between socioeconomic status and mortality appears to be attenuated by changing health behaviors, health policies and interventions among low socioeconomic groups should focus on health education and affecting change in populations that have notoriously poor health behaviors.

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