Introduction: Smoking has been shown to be associated with carotid atherosclerosis in cross-sectional and prospective studies in Western populations. However, few studies have examined the reversal of risk resulting from quitting smoking, and the results are conflicting.
Methods: Nine hundred and fifty-nine men aged 50 to 85 years were randomly selected from Phase 3 (2006-2007) of the Guangzhou Biobank Cohort Study into this cross-section study. Common carotid artery intima-media thickness (CCA-IMT) was measured by B-mode ultrasonography and carotid artery plaques were identified. Major cardiovascular risk factors including fasting triglyceride, low- and high-density lipoprotein (LDL and HDL)-cholesterol and glucose, systolic and diastolic blood pressure were assessed.
Results: CCA-IMT and the number of carotid plaque increased from never to former to current smokers (both P ¡Ü0.001). Among former smokers compared to current smokers, after adjustment for cigarette pack-years and other potential confounders, the adjusted odds ratios (95% confidence interval) for quitting for ¡°1-9 years¡±, ¡°10-19 years¡± and ¡°20+ years¡± were 0.77 (0.47, 1.26), 0.45 (0.26, 0.79) and 0.37 (0.17, 0.77) for presence of CCA atherosclerosis, and 0.69 (0.43, 1.12), 0.47 (0.27, 0.82) and 0.45 (0.23, 0.96) for presence of carotid plaques, respectively. Longer duration of quitting smoking was also significantly associated with decreasing risk of the severity of both CCA atherosclerosis and carotid plaques (all P¡Ü0.001).
Conclusion: Smoking cessation was beneficial in attenuating the risk of carotid atherosclerosis associated with cigarette smoking. The short duration of cessation in earlier studies is a likely explanation for the inconsistent results.