Smoking did not modify the effects of anti-TNF treatment on health-related quality of life among Australian ankylosing spondylitis patients

Objective. The aim of this study was to examine the impact of smoking on health-related quality of life (HRQoL) among AS patients who were taking biologic DMARDS. Methods. This is a longitudinal cohort study of AS patients with anti-TNF treatment in the Australian Rheumatology Association Database (2003-11). They were assessed using the 36-item Short Form Health Survey (SF-36), Assessment of Quality of Life (AQoL) and HAQ for spondylitis (HAQ-S) on a biannual basis. Linear mixed models were used to assess the impact of smoking on HRQoL outcomes over the first 2 years of treatment. Results. Four hundred and twenty-two patients [73% male, mean age 44.9 years (S.D. 12.7) provided 1189 assessments for the study. Current smokers (n = 79) were slightly younger, more likely to be male, less likely to use or to have previously used prednisolone and had a slightly shorter disease duration than past smokers (n = 138) or non-smokers (n = 205). After adjusting for smoking, gender, age, education, employment, co-morbidities and medication use, including DMARDs, anti-inflammatories and analgesics, all the HRQoL measures improved significantly over the study period and the improvements were not modified by smoking status (all P-values > 0.36). Current smokers tended to have a poorer HRQoL on the SF-36 physical score [-1.93 (95% CI -3.94, 0.09), P = 0.06] and the HAQ-S score [0.10 (95% CI -0.01, 0.20), P = 0.07] compared with non-smokers. Conclusion. Among AS patients, active smoking did not diminish or modify the improvements in HRQoL from anti-TNF treatment, even though current smokers compared with non-smokers tended to have poorer scores in some HRQoL measures.