Cigarette smoking correlates with disease activity, function and health assessment in the patients with ankylosing spondylitis

Objective To investigate the relationship between cigarette smoking, disease activity, functional limitation, and health status in Chinese patients with ankylosing spondylitis （AS）. Methods A total of 687 AS patients were recruited in this cross-sectional survey. Age, gender and smoking status were collected. Smoking status was obtained by a standard questionnaire involving smoking status （non-smoker, ex-smoker or current smoker）, the age when starting smoking and smoking status of family members. The course of disease, duration of morning stiffness, C-reactive protein （CRP） and erythrocyte sedimentation rate （ESR） were observed. The severity of morning stiffness, visual analogue scale （VAS） scores of systemic pain, nocturnal back pain and during whole day were recorded. The disease, functional limitation and health status were evaluated by using the Bath AS Disease Activity Index （BASDAI）, the Bath AS Functional Index （BASFI） and Health Assessment Questionnaire for Spondyloarthropathy （HAQ-S）. Correlation analysis was performed between duration of cigarette smoking and clinical parameters. Results Of all the 687 patients, 168 （24.5%） are current smokers, 108 were ex-smokers （15.7%） and 411 patients never smoked （59.8%）, respectively. The smokers had 4.0 （8.5） packs of cigarette per year. The family members of 186 patients （27.1%） smoked and family members of 501 cases （72.9%） did not smoke. Compared with non-smokers, current smokes had older age, longer duration of disease, more severe morning stiffness higher VAS of the systemic pain, nocturnal back pain and back pain, during whole day, HAQ-S, BASDAI scores, and level of CRP （all P < 0.05）. Compared with the ex-smokers, current smokers had older age and more severe morning stiffness （both P < 0.05）. The parameters did not significantly differ between non-smokers and ex-smokers （all P > 0.05）. Age （r_s = 0.255）, course of disease （r_s = 0.168）, duration of morning stiffness （r_s = 0.145）, degree of morning stiffness （r_s = 0.170）, systemic pain （r_s = 0.089）, nocturnal back pain （r_s= 0.133）, back pain during whole day （r_s = 0.116）, CRP （r_s=0.106）, BASDAI （r_s=0.114）, BASFI （r_s = 0.075） and HAQ-S （r_s = 0.092） were significantly correlated with duration of smoking （all P < 0.05）. Conclusion Cigarette smoking is correlated with disease activity, functional limitation and health status in AS patients.