Cooccurrence of lifestyle risk factors and the explanation of education inequalities in mortality: results from the GLOBE study

Background: To investigate whether the cooccurrence of two lifestyle risk factors (smoking, excessive alcohol consumption, physical inactivity in leisure time) has an additional contribution to the explanation of education inequalities in mortality, over and above the contribution of single risk factors. Methods: Prospective cohort study, 1991–1998, in the South East of the Netherlands. Participants were 16,980 men and women aged 15–74 years at baseline. Results: Education differences in the cooccurrence of risk factors were of a similar magnitude as education inequalities seen for single risk factors. A significant (P = 0.04) interaction effect on mortality was found between smoking and physical inactivity. Adjustment for both smoking and inactivity reduced the mortality hazard ratio of the lowest level of education by 30% (from 1.66 to 1.46). Further adjustment for the interaction between the two risk factors did not change the hazard ratio significantly. Conclusion: The cooccurrence of lifestyle risk factors did not provide any additional contribution to the explanation of education inequalities in mortality, over and above that of single risk factors. However, because risk factors tend to cooccur and have a higher prevalence among lower-educated people, it is still useful to focus interventions on more than one risk factor.