A back pain screening questionnaire developed for ankylosing spondylitis performs well for identifying the subset of axial psoriatic arthritis patients who have active symptoms, according to researchers.
The inflammatory back pain criteria didn’t perform as well when patients with established disease but no symptoms were included, though using a lower cutoff point for the questionnaire improved its sensitivity, the researchers reported in the Annals of the Rheumatic Diseases.
Previous investigations showed that the inflammatory back pain criteria, as defined by the Assessment of Spondyloarthritis International Society (ASAS), had low sensitivity and high specificity for axial involvement in psoriatic arthritis.
Those earlier studies may have registered suboptimal performance of the inflammatory back pain criteria by not distinguishing between patients with axial disease in remission and those with active symptoms, according to Muhammad Haroon, PhD, of the division of rheumatology at University Hospital Kerry in Tralee, Ireland, and his coinvestigators.
The present study, which they said represents a much larger cohort than earlier investigations, included 406 patients with psoriatic arthritis, about one-quarter of whom had rheumatologist-diagnosed axial psoriatic arthritis. The mean age of the axial psoriatic arthritis patients was 51 years and 53% were male.
The researchers found that the inflammatory back pain criteria had poor sensitivity but good specificity at 59% and 84%, respectively, in patients with established axial psoriatic arthritis, defined as axial disease regardless of whether it was active or in remission.
By contrast, the criteria had good sensitivity and good specificity at 82% and 88%, respectively, in patients who had active axial psoriatic arthritis, according to the investigators.
The standard cutoff points used by the ASAS inflammatory back pain criteria may be too high for screening for early disease or for evaluating patients already receiving systemic therapies for psoriatic disease, the investigators said.
Looking at a lower cutoff point of three of five ASAS criteria, sensitivity was “quite high” for detecting established axial psoriatic arthritis, they said, increasing from 59% to 84%, while specificity remained relatively high, decreasing from 84% to 80%.
“We suggest that the standard cutoffs for this questionnaire be used for patients with active axial psoriatic arthritis, and the lower cutoffs should be used among patients with established axial psoriatic arthritis, where patients can potentially be in remission or partial remission,” they wrote in their report.
These findings could have important implications for the use of this screening tool in patients with psoriatic arthritis; however, more research is needed to validate the observations, the researchers cautioned.
Dr. Haroon reported competing interests related to AbbVie, Pfizer, and Celgene.
SOURCE: Haroon M et al. Ann Rheum Dis. 2018 Dec 14. doi: 10.1136/annrheumdis-2018-214583.