Measurement and treatment of radiographic progression in ankylosing spondylitis: lessons learned from observational studies and clinical trials.

PURPOSE OF REVIEW: One of the major goals of treatment of ankylosing spondylitis is to prevent or slow the development of spinal new bone formation. Recent observational studies are compared with the results from clinical trials for the effects of tumor necrosis factor-alpha inhibitors (TNFi) and NSAIDs on radiographic measures of spinal damage.

RECENT FINDINGS: Data from clinical trials indicate that treatment up to 2 years with TNFi was not associated with a difference in rates of progression of spinal damage, compared with historical controls. These studies were based on open-label extensions, and analyzed as cohort studies. Recent observational studies have suggested that TNFi may reduce radiographic progression. The different conclusions may be related to the longer treatment and observation period of these observational studies, which may have permitted detection of changes in this slowly evolving process. There is emerging evidence from a clinical trial and retrospective studies that continuous NSAID use may slow radiographic progression.

SUMMARY: Lack of evidence that TNFi slows radiographic progression in ankylosing spondylitis in data from clinical trials may be because of the design of these studies, and possibly not a true null treatment effect.