Background: Cross-sectional studies revealed that cigarette smokers have lower high-density lipoprotein cholesterol (HDL-C) levels and higher levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) than nonsmokers. But prospective studies on the effects of cigarette smoking cessation on lipid profile have yielded inconclusive results.
Methods: Relevant English articles were retrieved by keyword searches of MEDLINE (1966-October 2000), Cochrane Library (2000, Issue 2), and cited references. Twenty-seven studies met the following inclusion criteria: (1) prospective cohort study including clinical trials, (2) measuring smoking status and lipid profile of HDL-C, TC, LDL-C, and TG, (3) reporting the changes of lipid concentrations in abstinent smokers, and (4) not using adjuvant antihyperlipidemic drugs.
Results: Overall Q statistics for net change of HDL-C, TC, LDL-C, and TG showed heterogeneity. Using a random-effects model, HDL-C level increased significantly [0.100 (CI 0.074 to 0.127) mmol/L] after smoking cessation. However, levels of TC [+0.003 (CI -0.042 to 0.048)], LDL-C [-0.064 (CI -0.149 to 0.021)], and TG [+0.028 (CI -0.014 to 0.071)] did not change significantly after smoking cessation.
Conclusions: Cigarette smoking cessation increases serum levels of HDL-C but not of TC, LDL-C, and TG.