The Mutual Impact of Smoking and Low Cholesterol on All-Cause, Non-Cardiovascular, and Cardiovascular Mortalities in Males

Abstract

The aim of the current study was to examine the possible relationship between the mutual effects of smoking and low cholesterol on all-cause, non-cardiovascular, and cardiovascular mortalities in males. This is a prospective cohort study of 30,179 males sampled from the Risk Factors and Life Expectancy (RIFLE) studies in the Italian population. The RIFLE data are from 19 different large-scale studies over a 9.5-year follow-up period. The Cox Proportional Hazard model was applied to analyze the data. The associations are presented as hazard ratios (HRs) with 95% confidence interval (CI). Cholesterol data were reported in categories. There were significant mortality risk mutual associations for never-smokers and those in the low cholesterol category (<160 mg/dl) for all-cause (HR = 3.13, 95% CI [1.69, 5.80]), and non-cardiovascular disease (CVD) (HR = 6.51, 95% CI [2.19, 19.33]) mortality in men with an insignificant risk for CVD mortality (HR = 1.90, 95% CI [0.85, 4.22]). There were significant mortality risk associations of the mutual effects of ex-smokers and low cholesterol for non-CVD in the first to third cholesterol categories (HR = 2.50, 95% CI [1.40, 4.46]; HR = 2.65, 95% CI [1.50, 4.71]; HR = 2.12, 95% CI [1.17, 3.82], respectively), but no significant findings for all-cause and CVD deaths. Furthermore, there were significant mortality risk association of mutual effects of current-smokers and low cholesterol for non-CVD (HR = 1.56, 95% CI [1.11, 2.28]) in the first category of cholesterol level, but insignificant risk associations for all-cause deaths (HR = 1.21, 95% CI [0.89, 1.66]). Interestingly, findings indicate a mutual protective association for current-smokers and low cholesterol (<160 mg/dl) for CVD risk in males (HR = 0.42, 95% CI [0.19, 0.91]). Findings of this study identified significant mortality risk association for mutual effects of never-smokers, ex-smokers, and low cholesterol for non-CVD. However, there is significant protective association for current-smokers and low cholesterol for CVD.

Keywords: low serum cholesterol; male; mortality; smoking status.