Measurement Properties of the Polymyalgia Rheumatica Activity Score: A Systematic Literature Review

Objective. To perform a COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN)-based systematic literature review of measurement properties of the Polymyalgia Rheumatica Activity Score (PMR-AS). Methods. PubMed, EMBASE, and CINAHL were broadly searched. English full-text articles, with (quantitative) data on ≥ 5 patients with PMR using the PMR-AS were selected. Seven hypotheses for construct validity and 3 for responsiveness, concerning associations with erythrocyte sedimentation rate, physical function, quality of life, clinical disease states, ultrasound, and treatment response, were formulated. We assessed the structural validity, internal consistency, reliability, and measurement error, or the hypotheses on construct validity or responsiveness of the PMR-AS based on COSMIN criteria. Results. Out of the identified 26 articles that used the PMR-AS, we were able to use 12 articles. Structural validity, internal consistency, construct validity, and responsiveness were assessed in 1, 2, 8, and 3 articles, respectively. Insufficient evidence was found to confirm structural validity and internal consistency. No data were found on reliability or measurement error. Although 60% and 67% of hypotheses tested for construct validity and responsiveness, respectively, were confirmed, there was insufficient evidence to meet criteria for good measurement properties. Conclusion. While there is some promising evidence for construct validity and responsiveness of the PMR-AS, it is lacking for other properties and, overall, falls short of criteria for good measurement properties. Therefore, further research is needed to assess its role in clinical research and care.