Associations between leukocyte count and lipid-related indices: Effect of age and confounding by habits of smoking and alcohol drinking.

Leukocyte count in peripheral blood is an acute-phase reactant and is associated with the risk of atherosclerotic diseases. Blood lipid profile, a major risk factor of cardiovascular disease, is known to be associated with leukocyte count, but it remains to be determined how this association is affected by other factors including lifestyle and age. The subjects were 11261 Japanese middle-aged men (3065 years old) who had received health checkup examinations. The relationships of leukocyte count with lipid-related indices (ratio of LDL cholesterol to HDL cholesterol [LDL-C/HDL-C], ratio of triglycerides to HDL cholesterol [TG/HDL-C] and cardiometabolic index [CMI]) were investigated. Leukocyte count, LDL-C/HDL-C, TG/HDL-C and CMI were significantly higher in smokers than in nonsmokers, while leukocyte count and LDL-C/HDL-C were significantly lower in regular drinkers than in nondrinkers. Both in overall subjects and subjects without habits of smoking and drinking, LDL-C/HDL-C, TG/HDL-C and CMI were significantly higher in the 2nd and 3rd tertiles for leukocyte count than in the 1st tertile and tended to be higher with an increase of the tertile. Odds ratios for high TG/HDL-C and high CMI of the 3rd vs. 1st tertiles for leukocyte count tended to be lower with an increase of age, and odds ratios for high TG/HDL-C and high CMI of the interaction term, consisting of age (6065 vs. 30~39 years) and tertile (3rd vs. 1st tertiles for leukocyte count), were significantly lower than the reference level. In conclusion, leukocyte count is associated with lipid-related indices, and the associations are independent of smoking and alcohol drinking and tend to be weaker with an increase of age in Japanese middle-aged men.