Smoking and the risk of systemic lupus erythematosus.

This study aims to study the association of smoking with the development of systemic lupus erythematosus (SLE). The study included 223 SLE patients (92 % women, mean age 47 years) and 1,538 population controls of similar age and socioeconomic status living in the metropolitan area of Finland. The history of smoking in patients and controls was obtained by personal interview. The prevalence of current and past smoking was more common in patients with SLE than in controls. In women with a history of daily smoking for more than 1 year, the odds ratio (OR) for SLE was 1.45 (95 % CI 1.07-1.97), in current daily smokers as compared to never smokers, the OR was 1.55 (1.00-2.40), and in ex-smokers versus never smokers 1.80 (1.15-2.83). The number of men with SLE, who had smoked more than 100 cigarettes during their lifetime was higher than in male controls (p = 0.026). A history of smoking is significantly though modestly associated with the development of SLE.