Cigarette smoking and risk of adult-onset Still disease: a propensity score matching analysis.

Background: Environmental factors play an important role in the pathogenesis of rheumatic diseases. Smoking is thought to be a risk factor for autoimmune rheumatic diseases.

Aims: The purpose of the present study was to assess the association between smoking and adult-onset Still disease (AOSD) and the effect of smoking on outcomes of this disease.

Methods: In this case-control study, patients with AOSD who met the Yamaguchi criteria, were older than 16 years at the disease onset and were in follow-up for at least 12 months were consecutively enrolled in the study. The outcome of AOSD was assessed by acquiring remission on treatment, remission off treatment, time to remission and rate of flare. The smoking status of participants was defined by direct or phone interviews. Individuals who had smoked daily for at least 6 months were defined as a smoker. We performed propensity score matching analyses by using four parameters, including age, sex, educational status and marital status.

Results: Propensity score matching resulted in 72 patients with AOSD and 216 matched controls. The number of ever smokers in the AOSD and control groups were 11 (15.3%) and 25 (11.6%) respectively. There was no significant increase in the risk of AOSD in multivariate analysis after adjustment for age, sex, marital status and educational level. There were no significant differences in the outcomes of AOSD between ever and never smokers.

Conclusions: Smoking probably is not a risk factor for AOSD and did not affect the response to treatment.