Minority of patients with nr-axSpA in study progressed to ankylosing spondylitis

A limited number of patients diagnosed with nonradiographic axial spondyloarthritis will develop ankylosing spondylitis, according to recently published research.

Researchers identified 83 patients who met Assessment of Spondyloarthritis International Society (ASAS) criteria for nonradiographic axial spondyloarthritis (nr-axSpA) from the Rochester Epidemiology Project, including 18 patients in an imaging arm and 65 patients in a clinical arm of the project. A combination of diagnostic and procedural codes for back pain, HLA-B27 status and pelvis MRI was used to identify patients in the database who were seen between 1985 and 2010. The average patient age at inclusion was 33.3 years with a mean of onset of back pain of 30.3 years. About half (53%) of the patients were men and the mean follow-up time for the cohort was 10.6 years.

Survival analysis revealed 16 patients (19%) developed radiographic sacroiliitis that qualified as ankylosing spondylitis (AS) based on modified New York criteria. The probability of disease status remaining at nr-axSpA at 5 years was 93.6%, at 10 years was 88.3% and at 15 years was 82.7%.

Using the last date of a negative pelvis imaging scan as a cut-off threshold, the sensitivity analysis showed the probability for remaining with nr-axSpA at 5 years was 89.6%, at 10 years was 70.4% and at 15 years was 53.9%. A hazard ratio of 3.5 was calculated for patients to develop AS in the imaging arm (28%) compared to the clinical arm (17%). A nonstatistically significant trend for men to progress more often than women was observed. – by Shirley Pulawski

Reference:

Wang R, et al. Paper #709. Presented at: American College of Rheumatology Annual Meeting; Nov. 7-11, 2015; San Francisco.

Disclosure: The researchers report no relevant financial disclosures.