Gender-specific combined effects of smoking and hypertension on cardiovascular disease mortality in elderly Koreans: The Kangwha Cohort Study

Abstract

OBJECTIVE: We examined gender-specific combined effects of smoking and hypertension on risk of mortality from cardiovascular disease in elderly Korean men and women. STUDY DESIGN: This study followed a cohort of 6097 residents (2593 men, 3504 women) in the general population of Kangwha County, aged ≥55 years in March 1985 and examined their cause-specific mortality for 20.8 years, up to December 31, 2005. All participants were followed up more than once after the 1985 survey. MAIN OUTCOME MEASURES: We calculated hazard ratios for mortality for the combined sets of smoking habits and blood pressure levels using the Cox proportional-hazard model. The set of non-smokers with normal blood pressure served as a reference group. RESULTS: During the 20.8 years of follow-up, 759 people died from cardiovascular disease. The risk of mortality from cardiovascular disease and stroke according to smoking or hypertension was not different between men and women. However, the risk among smokers combined with hypertension was higher in men than in women; the multivariable-adjusted hazard ratios (95% CI) for mortality from cardiovascular disease and stroke were 4.52 (1.67-12.21) and 6.37 (1.57-25.85) in men and 2.11 (1.37-3.24) and 2.41 (1.44-4.01) in women, respectively. CONCLUSIONS: The magnitude of the joint effects of smoking and hypertension on cardiovascular disease and stroke mortality was different between men and women. This study suggests that combining quitting smoking with lowering blood pressure could contribute to preventing cardiovascular disease and stroke, especially in men.