GENDER DIFFERENCES IN PLATELET COUNT AND ITS ASSOCIATION WITH CIGARETTE-SMOKING IN A LARGE COHORT IN ISRAEL

Cigarette smoking has an effect on platelet function and aggregation although the sensitivity of platelet count in reflecting this phenomenon is not known. The association of platelet count with smoking habits was examined in a cohort of 5017 Israeli industrial workers aged 20-64 years. Males had a significantly lower age-adjusted mean platelet count than females (225,600 vs 247,800/mu-l; p < 0.001). Female smokers had lower platelet counts than non-smokers (231,000 for heavy vs 252,000 for never smokers) with a strong dose-response relationship (p < 0.0001), whereas among males platelet count was slightly higher in smokers (224,000 for non-smokers vs 227,000 for heavy smokers; p = 0.243). The difference in platelet count between the sexes remained almost identical after controlling for smoking status and hematocrit. In multiple regression analysis, the negative association between smoking and platelet count in women remained highly significant (p < 0.001) after controlling for ethnic origin, alcohol consumption, body mass, hematocrit, cholesterol and HDL-cholesterol, whereas for males the slight positive association was not significant. The reduced platelet count observed in males compared with females and in female smokers, suggests that platelet count may reflect sex differences in hemostasis and the effects of smoking on the hemostatic system. This may have implications for the mechanisms underlying the pathogenesis of ischemic heart disease and should be explored further.