Toward a Core Outcome Measurement Set for Polymyalgia Rheumatica: Report from the OMERACT 2018 Special Interest Group

Test-retest reliability of pain VAS/NRS, stiffness VAS/NRS, HAQ-DI and mHAQ in polymyalgia rheumatica: An OMERACT study

OBJECTIVE

To examine the test-retest reliability of four measurement instruments in polymyalgia rheumatica (PMR): pain severity visual analogue scale (VAS) / numerical rating score (NRS), stiffness severity VAS/NRS, the Health Assessment Questionnaire-Disability Index (HAQ-DI) and the modified Health Assessment Questionnaire (mHAQ).

METHOD

Two prospectively collected datasets were used. All participants had a diagnosis of PMR and only those with stable disease were included in analyses. Measurement instruments were administered twice, with a testing interval of two to six weeks. The intra-class correlation coefficient (ICC) was calculated using a two-way mixed effects model looking for absolute agreement. ICC values of 0.8-0.9 were deemed representative of good test-retest reliability, whilst values >0.9 were representative of excellent test-retest reliability.

RESULTS

From the first dataset, 38 participants were analysed. The ICC between baseline and 2 weeks for pain VAS, stiffness VAS, HAQ-DI and mHAQ were 0.84, 0.82, 0.92 and 0.92 respectively. From the second dataset, 58 participants were included in the analysis for pain NRS, 59 for stiffness NRS and 78 for mHAQ. The ICC between baseline and follow-up for pain NRS, stiffness NRS and mHAQ were 0.80, 0.83 and 0.87 respectively.

CONCLUSION

Pain severity VAS/NRS, stiffness severity VAS/NRS, HAQ-DI and mHAQ all demonstrate good to excellent test-retest reliability in a PMR patient population.

Development and psychometric evaluation of the PMR-Impact Scale: a new patient reported outcome measure for polymyalgia rheumatica

OBJECTIVES

PMR causes pain, stiffness and disability in older adults. Measuring the impact of the condition from the patient's perspective is vital to high-quality research and patient-centred care, yet there are no validated patient-reported outcome measures (PROMs) for PMR. We set out to develop and psychometrically evaluate a PMR-specific PROM.

METHODS

Two cross-sectional postal surveys of people with a confirmed diagnosis of PMR were used to provide data for field testing and psychometric evaluation. A total of 256 participants completed the draft PROM. Distribution of item responses was examined, and exploratory factor analysis and Rasch analysis were used to inform item reduction, formation of dimension structure and scoring system development. Some 179 participants completed the PROM at two time points, along with comparator questionnaires and anchor questions. Test-retest reliability, construct validity and responsiveness were evaluated.

RESULTS

Results from the field-testing study led to the formation of the PMR-Impact Scale (PMR-IS), comprising four domains (symptoms, function, psychological and emotional well-being, and steroid side effects). Construct validity and test-retest reliability met accepted quality criteria for each domain. There was insufficient evidence from this study to determine its ability to detect flares/deterioration, but the PMR-IS was responsive to improvements in the condition.

CONCLUSION

The PMR-IS offers researchers a new way to assess patient-reported outcomes in clinical studies of PMR. It has been developed robustly, with patient input at every stage. It has good construct validity and test-retest reliability. Further work is needed to fully establish its responsiveness and interpretability parameters, and to assess its real-world clinical utility.

Not just pain and morning stiffness duration in the daily experience of patients with polymyalgia rheumatica. Does the rheumatologist listen to all patient-reported outcomes?

Patient-reported outcomes (PROs) provide a means for patients to communicate with their care teams about their disease. Polymyalgia rheumatica (PMR) is considered to be one of the most common inflammatory rheumatic diseases in older adults. The Visual Analogue Scale (VAS) of pain is the only PRO assessed by the PMR activity score (PMR-AS), which is still the only validated score for monitoring disease activity in patients affected with PMR. Other PROs such as fatigue, sleep disturbances, depressive symptoms, and patient’s perspective related to adverse effects of prednisolone are still unmet needs. This short communication suggests the gerontorheumatological outpatient clinic as an answer.

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 5 databases. Two researchers were involved in screening, data extraction, and risk of bias assessment. Once outcomes and instruments used were identified and categorized, key instruments were selected for further review through a consensus process. Studies on measurement properties of these instruments were appraised against the COSMIN-OMERACT (COnsensus-based Standards for the selection of health Measurement Instruments-Outcome Measures in Rheumatology) checklist to determine the extent of evidence supporting their use in PMR.

RESULTS

Forty-six studies were included. In decreasing order of frequency, the most common outcomes (and instruments) used were markers of systemic inflammation [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)], pain [visual analog 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 the Health Assessment Questionnaire. Five studies evaluated measurement properties of these instruments, but none met all of the COSMIN-OMERACT checklist criteria.

CONCLUSION

Measurement of outcomes in studies of PMR lacks consistency. The critical patient-centered 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.