Clinical trial discrimination of physical function instruments for psoriatic arthritis: a systematic review

Abstract Objectives Physical function (PF) is a core domain to be measured in randomized controlled trials (RCTs) of psoriatic arthritis (PsA), yet the discriminative performance of patient reported outcome measures (PROMs) for PF in RCTs has not been evaluated systematically. In this systematic review, we aimed to evaluate the clinical trial discrimination of PF-PROMs in PsA RCTs. Methods We searched PubMed and Scopus databases in English to identify all original RCTs on biological and targeted synthetic disease modifying anti-rheumatic drugs (DMARDs) conducted in PsA. We assessed quality in each article using the OMERACT good method checklist. Effect sizes (ES) for the PF-PROMs were calculated and appraised using a priori hypotheses. Evidence supporting clinical trial discrimination for each PF-PROM was summarized to derive recommendations. Results 35 articles from 31 RCTs were included. Four PF-PROMs had data for evaluation: HAQ-Disability Index (DI), HAQ-Spondyloarthritis (S), and Short Form 36-item Health Survey Physical Component Summary (SF-36 PCS) and Physical Functioning domain (SF-36 PF). As anticipated, higher ES values were observed for intervention groups than the control groups. Across all studies, for HAQ-DI, the median ES were -0.73 and -0.24 for intervention and control groups, respectively. Whereas for SF-36 PCS, the median ES were 0.77 and 0.23. for intervention and control groups, respectively. Conclusion Clinical trial discrimination was supported for HAQ-DI and SF-36 PCS in PsA with low risk of bias; and for SF-36 PF and HAQ-S with some caution. More studies are required for HAQ-S.