Social class disparities in risk factors for disease: eight-year prevalence patterns by level of education

This article examines the associations between education, a primary indicator of social class, and six risk factors for disease. Data are presented on a sample of 3,349 individuals ages 25-74 years who participated in one of four cross-sectional surveys conducted by the Stanford Five-City Project between 1979 and 1986. The six risk factors examined are knowledge about health, cigarette smoking, hypertension, serum cholesterol, body mass index, and height. A highly significant pattern of associations was found between education level and the six risk factors, in the direction of higher risk among those with lower education (all P values less than 0.01). These associations persisted for both sexes and in the younger as well as the older age groups, with the exception of cholesterol values for males and for those in the 50 to 74-year-old age group. Furthermore, all associations remained highly significant after controlling for income and occupation, two other indicators of social class. When a summary-adjusted risk score was plotted against year of survey for the five education levels, a gradient of effect was observed where each progressive education level showed a decrease in total risk score. This gradient was replicated in all four cross-sectional surveys, providing evidence for the consistency of the findings over time.