Effect of tumor necrosis factor inhibitors on spinal radiographic progression in patients with ankylosing spondylitis

AimTo evaluate the effect of tumor necrosis factor inhibitors (TNFi) on spinal radiographic progression in patients with ankylosing spondylitis (AS). MethodsSubjects were selected from patients at a single tertiary hospital between 1995 and 2014. Patients who used TNFi with baseline and paired follow-up radiographic data with a minimum interval of 2years were included. Time to start TNFi was defined as the time from symptom onset to the start of TNFi use. TNFi index was defined as the ratio of the period of TNFi use to the entire period of disease. Radiographic damage was assessed by the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Univariable and multivariable linear regression analyses were used to identify factors associated with radiographic progression. ResultsA total of 151 patients were included in the analysis. Seventeen (11.3%) patients were female and mean mSASSS/year was 1.01 units/year. Mean X-ray follow-up duration was 102.954.9months. Mean time from symptom onset to start of TNFi use was 104.8 +/- 83.6months (median 84months) and mean TNFi index was 42.9 +/- 23.8% (median 40.9%). In multivariable analysis, initial mSASSS, initial C-reactive protein, body mass index, current smoker, and delayed start of TNFi use were associated with radiographic progression. Presence of peripheral arthritis and the TNFi index were negatively associated with radiographic progression. ConclusionsA delay in starting TNFi use and low TNFi index were associated with radiographic progression. Early and long-term use of TNFi appear to reduce spinal radiographic progression in patients with AS.