Pack-year Smoking Associated with Poorer Functional Status, Worsened Spinal Mobility and More Radiological Damages in Axial Spondyloarthritis

Abstract

Introduction: To study the dose-response relationship between smoking and axial Spondyloarthritis (axSpA) disease outcome.

Method: One hundred and sixty participants with axSpA were recruited from a single rheumatology center. All of them fulfilled the classification criteria for axSpA by the Assessment of SpondyloArthritis International Society (ASAS). Clinical, demographic and biochemical data was collected. Participants were asked for detailed smoking histories including past and current smoking, smoking duration and quantity. Radiographs of cervical and lumbar spine were performed for modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and modified New York (MNY) criteria for radiological sacroiliitis. Ankylosing Spondylitis Disease Activity Score (ASDAS) was calculated based on C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Univariate and multivariate regression models were performed to determine the associations between pack-year smoking and different disease outcomes.

Results: Among the participants, 62 (38.7%) were either current (N = 39) or former smokers (N = 23). Ex-smokers quit smoking by 18.8 ± 12.4 years. The mean pack-year for patients who had ever smoked was 19.4 ± 23.1. In univariate analyses, pack-year smoking was associated with BASFI (p < 0.001), modified Schober test (p = 0.01) and mSASSS (p < 0.001). Multivariate regression models showed independent dose-response associations between pack-year of smoking and BASFI (SC 0.23; 95% CI 0.01 to 0.06; p = 0.004), modified Schober test (SC −0.16; 95% CI −0.03 to 0.00; p = 0.049) and mSASSS (SC 0.22; 95% CI 0.09 to 0.47; p = 0.01).

Conclusion: In Chinese axSpA patients, pack-year smoking was independently associated with poorer functional status, worsened spinal mobility and more radiological damages. Smoking cessation should be encouraged in patients with axSpA.