Factors Predictive of Radiographic Progression in Ankylosing Spondylitis.

OBJECTIVE

Using a longitudinal observational cohort of ankylosing spondylitis (AS) patients, we sought to identify progression rates and factors predictive of spinal progression. As a secondary aim, we analyzed the effect of tumor necrosis factor inhibitor (TNFi) treatment on radiographic progression.

METHODS

AS patients who had baseline and follow-up cervical and lumbar radiographs were included in the study. Radiographic damage was assessed by the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). A change of 2 mSASSS units in 2 years was defined as progression. The characteristics of the study group such as demographic, clinical, laboratory, and treatment history were collected.

RESULTS

There were 350 patients in the study. The mean ± SD mSASSS increased from 9.3 ± 15.8 units at baseline to 17.7 ± 21.7 units by the sixth year. Mean ± SD changes in mSASSS between the years 0 to 2, 2 to 4, and 4 to 6 were 1.23 ± 2.68, 1.47 ± 2.86, and 1.52 ± 3.7 units, respectively. Overall, 24.3% of the group progressed over 2 years. Male sex (hazard ratio [HR] 2.46 [95% confidence interval (95% CI) 1.05, 5.76]), the presence of baseline damage (HR 7.98 [95% CI 3.98, 16]), increased inflammatory markers (log C-reactive protein level HR 1.35 [95% CI 1.07, 1.70]), and TNFi use (HR 0.82 [95% CI 0.70, 0.96]) were predictive of radiographic progression. There was a 20% reduction in the rate of progression with TNFi.

CONCLUSION

Male sex, the presence of baseline damage, active disease state, and higher inflammatory markers confer a high risk for disease progression. Treatment with TNFi showed a disease-modifying effect by slowing the rate of radiographic progression.