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Published on: October 17, 2018
External validation of the polymyalgia rheumatica impact scale: a prospective cohort study
Lien Moreel1,2, Michaël Doumen3,4, Albrecht Betrains1,2
1Department of General Internal Medicine, UZ Leuven, Leuven, Belgium.
Objectives:
To externally validate the PMR impact scale (PMR-IS).
Methods:
We conducted a prospective cohort study at the University Hospitals Leuven, Leuven, Belgium. Recently diagnosed PMR patients were included between July 2022 and December 2023 and followed until 1 year after diagnosis. All patients completed the PMR-IS, HAQ Disability Index, 36-item Short Form and a visual analogue scale for pain at every visit. Internal consistency, floor and ceiling effects, construct validity, responsiveness and discriminatory power for detecting relapse on the PMR-IS were assessed.
Results:
Fifty-five PMR patients (mean age 71 years, 47% female) were included, who had a total of 246 visits. Internal consistency, construct validity and responsiveness met the quality criteria for the symptoms, function and emotional and psychological well-being subdomains. The internal consistency of the glucocorticoid side effects subdomain was insufficient and only one of the three hypotheses for construct validity were met. The function and emotional and psychological well-being subdomains showed a floor effect, while no ceiling effect was observed. The symptoms, function and emotional and psychological well-being subdomains had a good discriminatory power for detecting relapse [area under the curve (AUC) 0.89, 0.86 and 0.72, respectively], but the PMR activity score performed better (AUC 0.94, P < 0.05 for all subdomains).
Conclusion:
This study validates the good measurement properties of the symptoms, function and emotional and psychological well-being subdomains of the PMR-IS. In contrast, the glucocorticoid side effects subdomain did not show adequate internal consistency and construct validity, necessitating further validation and possibly refinement of its items prior to application in clinical trials or daily practice.
Insights
This study validated the Polymyalgia Rheumatica Impact Scale (PMR-IS) in patients with polymyalgia rheumatica. The symptoms, function, and well-being subscales showed good measurement properties, but the side effects scale needs further refinement.
Area of Science:
- Rheumatology
- Clinical Measurement
- Patient-Reported Outcomes
Background:
- Polymyalgia Rheumatica (PMR) significantly impacts patient quality of life.
- Validated instruments are crucial for assessing PMR's effects on patients.
- The PMR Impact Scale (PMR-IS) aims to capture these effects.
Purpose of the Study:
- To externally validate the measurement properties of the PMR Impact Scale (PMR-IS).
- To assess the reliability and validity of the PMR-IS in a real-world clinical setting.
Main Methods:
- Prospective cohort study including 55 recently diagnosed PMR patients.
- Patients completed the PMR-IS, HAQ-DI, SF-36, and VAS for pain.
- Assessed internal consistency, construct validity, responsiveness, and discriminatory power.
Main Results:
- Symptoms, function, and emotional well-being subscales demonstrated good internal consistency, construct validity, and responsiveness.
- The glucocorticoid side effects subdomain showed insufficient internal consistency and construct validity.
- Discriminatory power for relapse detection was good for most subscales, though the PMR activity score performed better.
Conclusions:
- The symptoms, function, and emotional/psychological well-being subscales of the PMR-IS are validated for use.
- The glucocorticoid side effects subdomain requires further validation and potential item refinement.
- The PMR-IS shows promise for assessing PMR impact in clinical practice and research.
