Outcomes measured in polymyalgia rheumatica and measurement properties of instruments considered for the OMERACT core outcome set: A systematic review

Objective To systematically identify the outcome measures and instruments used in clinical studies of polymyalgia rheumatica (PMR) and to evaluate evidence about their measurement properties.

Methods Searches based on the MeSH term ‘polymyalgia rheumatica’ were carried out in five databases. Two researchers were involved in screening, data extraction and risk of bias assessment. Once outcomes and instruments used were identified and categorised, key instruments were selected for further review through a consensus process. Studies on measurement properties of these instruments were appraised against the COSMIN-OMERACT (Outcome Measures in Rheumatology) checklist to determine the extent of evidence supporting their use in PMR.

Results 46 studies were included. In decreasing order of frequency, the most common outcomes (and instruments) used were: markers of systemic inflammation (ESR/CRP), pain (visual analogue scale (VAS)), stiffness (duration in minutes) and physical function (elevation of upper limbs). Instruments selected for further evaluation were ESR, CRP, pain VAS, morning stiffness duration and Health Assessment Questionnaire. Five studies evaluated measurement properties of these instruments, but none met all of the COSMINOMERACT checklist criteria.

Conclusion Measurement of outcomes in studies of PMR lacks consistency. The critical patient-centred domain of physical function is poorly assessed. None of the candidate instruments considered for inclusion in the core outcome set had high quality evidence, derived from populations with PMR, on their full range of measurement properties. Further studies are needed to determine whether these instruments are suitable for inclusion in a Core Outcome Measurement set for PMR.