TY - JOUR T1 - The association between smoking and the development of psoriatic arthritis among psoriasis patients JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 219 LP - 224 DO - 10.1136/ard.2010.147793 VL - 71 IS - 2 AU - Lihi Eder AU - Sutha Shanmugarajah AU - Arane Thavaneswaran AU - Vinod Chandran AU - Cheryl F Rosen AU - Richard J Cook AU - Dafna D Gladman Y1 - 2012/02/01 UR - http://ard.bmj.com/content/71/2/219.abstract N2 - Aim To investigate the association between smoking and psoriatic arthritis (PsA) among patients with psoriasis and its interaction with the HLA-C*06 allele. Methods In this exploratory case–control study, smoking status was determined at the time of the diagnosis of arthritis for PsA patients and at their first study visit for psoriasis patients, when they were confirmed not to have PsA. The proportions of patients exposed to smoking were compared in patients with PsA to those with psoriasis alone. A logistic regression model was constructed to test the independent association of smoking and PsA after adjusting for potential confounders. The statistical interaction between HLA-C*06 and smoking was tested through a regression model. Results The proportions of current and past smokers were higher in the psoriasis group compared with the PsA group (30.2% vs 23.4% and 26.7% vs 22.3%, p=0.001, respectively). On multivariate analysis being a current smoker versus a lifetime non-smoker remained inversely associated with PsA (OR 0.57, p=0.002), while past smoker versus lifetime non-smoker status was no longer significant. In a subgroup analysis, smoking remained inversely associated with PsA only among patients who were HLA-C*06 negative. Regression analysis revealed that the interaction between smoking status (ever smoked vs lifetime non-smoker) and HLA-C*06 was statistically significant (p=0.01). Conclusion Smoking may be inversely associated with PsA among psoriasis patients. This association is not present among HLA-C*06-positive individuals. ER -