CRP levels are elevated in smokers but unrelated to the number of cigarettes and are decreased by long-term smoking cessation in male smokers.

Background: It is not clear whether there is a dose-response relationship between the number of cigarettes smoked per day and CRP level and whether there is a relationship between the length of smoking cessation and CRP level.

Methods: Geometric mean levels of CRP were compared in smoking status groups for 1926 men aged 40 to 69 years using analysis of covariance.

Results: After adjusting for several confounding factors, geometric mean levels of CRP (mg/L) were significantly different among the three smoking status groups (0.41 in non-smokers, 0.57 in current smokers, 0.48 in past smokers, P < 0.05). A linear trend was not found in the relationship between CRP level and number of cigarettes smoked per day. The mean CRP level in the long cessation (> or =5 years) group was significantly lower than that in the short cessation (<5 years) group (0.45 vs. 0.58, P < 0.05) and similar to that in the non-smokers group (0.45 vs. 0.41, NS).

Conclusions: CRP levels in current smokers are elevated but unrelated to the number of cigarettes smoked per day. In past smokers, long-term smoking cessation may contribute to the reduction in risk of development of cardiovascular diseases through inflammatory mechanisms.