Increased prevalence of cigarette smoking in Japanese patients with sarcoidosis.

Background And Objective: Several studies have shown that individuals with sarcoidosis in Western populations are less likely to have smoked before diagnosis. Epidemiological characteristics of sarcoidosis are known to differ between Japanese and Westerners. Therefore, the relationship between cigarette smoking and sarcoidosis in a Japanese population was investigated.

Methods: Three hundred eighty-eight patients newly diagnosed with sarcoidosis between 2000 and 2008 were retrospectively identified. The results of two large surveys of smoking prevalence in Japan provided reference data. Specific clinical manifestations of sarcoidosis were compared between current smokers and never-smokers, after excluding former smokers.

Results: The prevalence of current smokers at the time of the diagnosis of sarcoidosis was 59.6% in men and 27.9% in women. With the exception of men in their 30s, the prevalence was higher in all age groups compared with the general Japanese population. The prevalence of lung parenchymal involvement tended to be higher in current smokers than in never-smokers (odds ratio = 1.33 (0.99-1.77), P = 0.054).

Conclusions: This retrospective cohort study suggests that smoking prevalence is higher in Japanese sarcoidosis patients than that reported in Western sarcoidosis patients and that there could be different relationships between smoking and the development of sarcoidosis in these populations.