Background: Smoking is closely linked to socioeconomic status and risk of death. We examined the extent to which educational disparities in mortality can be explained by smoking.
Methods: We analysed data from 513,552 men and women aged 25-69 years, excluding individuals with a history of cardiovascular disease, diabetes or cancer. The educational level was lower (less than 10 years), upper (10-12 years) and higher (13 or more years). We employed the direct method to estimate age-adjusted mortality rates and used the Cox proportional hazards model to calculate hazard ratios, using a higher educational level as the reference level. We ran models among non-smokers with interaction terms, educational level and another variable. Based on Akaike information criterion, we performed stratified analyses by marital status among non-smokers.
Results: The hazard ratio for lower educational level in men was 1.38 (1.31-1.45) in non-smokers and 1.57 (1.49-1.66) in smokers. The figures for women were almost identical. Among non-smoking men, the hazard ratio for lower educational level was 1.28 (1.21-1.35) for the ever married and 2.20 (1.93-2.52) for the unmarried men. In women the figures were the same. For non-smoking men and women combined, the population attributable risk ascribed to upper or lower educational level was 17% for the ever married and 35% for the unmarried.
Conclusions: