Cigarette smoking and disease activity in systemic lupus erythematosus.

To investigate the effect of cigarette smoking on disease activity and cumulative organ damage in systemic lupus erythematosus (SLE). Methods. Extensive clinical and demographic variables, including current and previous cigarette smoking, were collected from 111 SLE patients using a detailed interview-administered questionnaire. Disease activity was estimated with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Cumulative organ damage was measured by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR). Smoking status was correlated with disease activity and cumulative organ damage, while statistically adjusting for the individual effects of potentially confounding demographic and clinical variables using analysis of variance followed by Fisher's least significant difference method. Results. Current smokers demonstrated significantly higher (p < 0.001) SLEDAI scores (15.6 +/- 7.8) than ex-smokers (9.63 +/- 6.00), and never smokers (9.03 +/- 5.75). This association remained significant (p = 0.001) after adjusting for all covariates, including ethnicity, education level, income level, alcohol use, age of onset of SLE, current age, mean duration of SLE, marital status, and hydroxychloroquine therapy. Current smokers also demonstrated significantly (p = 0.003) higher scores for both the neurological and non-neurological components of SLEDAI. There was no significant difference in the SLICC/ACR scores across the various smoking groups, although there was a trend for more severe disease in current smokers. Conclusion. Cigarette smoking is associated with increased disease activity in SLE. These data further establish the association of SLE with cigarette smoking, and suggest that individuals with SLE should avoid all exposure to tobacco products.