OBJECTIVES: To examine concurrent validity and discrimination of modified minimal disease activity (mMDA) criteria in peripheral spondyloarthritis (pSpA) following OMERACT filter principles and determine predictors of mMDA response.

METHODS: Four mMDA versions were derived in the ABILITY-2 study using the SPondyloArthritis Research Consortium of Canada (SPARCC) or Leeds Enthesitis Index (LEI) but excluding psoriasis. To assess concurrent validity, mMDA versions were correlated with Peripheral SpondyloArthritis Response Criteria (PSpARC) remission, Ankylosing Spondylitis Disease Activity Score for inactive disease (ASDAS ID), and physician global. Treatment discrimination was assessed between adalimumab and placebo at week 12. Multiple logistic regression was used to determine baseline predictors of long-term mMDA responses and sustained mMDA.

RESULTS: The four mMDA versions showed a stronger positive correlation with PSpARC remission (r

CONCLUSIONS: All four versions of mMDA showed concurrent validity and discriminated well between adalimumab and placebo treatment groups. Early mMDA response is a more consistent predictor of long-term mMDA achievement than baseline characteristics. The 5 of 6 versions of mMDA could be an appropriate treatment target in pSpA patients.