Is cigarette smoking an effect modifier of the relation between antihypertensive therapy and blood lipids?

We examined the relation between current use of antihypertensive medications and lipid levels in relation to smoking status. We used data from cross-sectional random sample surveys conducted between 1981 and 1993 in two southeastern New England communities. The analysis included 3,027 normotensive, 1,416 untreated hypertensive, and 1,174 treated hypertensive survey respondents between 40 and 64 years of age. After adjustment for body mass index, diabetes mellitus, alcohol use, use of medications with adverse lipid effects, age, and sex, the estimated mean high-density-lipoprotein- cholesterol level among hypertensives using beta-blockers [44.6 mg per dl; 95% confidence interval (CI) = 43.l-46.1] was lower than that for either untreated hypertensives (48.5 mg per dl; 95% CI = 47.8-49.2) or normotensives (47.1 mg per dl; 95% CI = 46.6-47.6). This pattern was similar among smokers and nonsmokers. Smokers treated with beta-blockers, however, had particularly low levels of high-density-lipoprotein-cholesterol (43.4 mg per dl; 95% CI = 40.7-46.l), compared with non-smokers using beta-blockers (45.8 mg per dl; 95% CI = 44.247.3). Low levels of high-density-lipoprotein-cholesterol may increase the risk of coronary heart disease among smokers using beta- blockers.