Smoking is highly associated with discoid lupus erythematosus and lupus erythematosus tumidus: analysis of 405 patients

Background Environmental factors appear to play a role in the pathogenesis of lupus erythematosus (LE). Objective To determine the association between cigarette smoking and various types of cutaneous LE. Design Retrospective descriptive study at a dermatology clinic of a tertiary referral hospital. Methods All patients diagnosed with cutaneous and/or systemic LE from January 2000 to December 2012 at the outpatient clinic for dermatological autoimmune diseases were analyzed. Results 405 patients were diagnosed with LE. Smokers were more common among patients with cutaneous LE, especially those with LE tumidus or discoid LE. The frequency of cigarette smokers was not significantly higher among patients with other LE-specific skin lesions and patients with systemic LE compared to the general population. Smoking at the onset of disease was associated with LE tumidus (odds ratio OR 4.5), discoid LE (OR 2.05), the male gender (OR 3.31), age<50 years (OR 1.03), and photosensitivity (OR 2.07). Limitations A retrospective descriptive study at a tertiary referral hospital. Conclusion Smoking is highly associated with cutaneous LE, but not systemic LE. Various risk factors appear to be involved in the pathogenesis of cutaneous and systemic LE.