Psychometric properties of performance based tests in patients with Fibromyalgia: A systematic review.

Fibromyalgia (FM) impacts patients' health status, functioning and quality of life. Accurate diagnosis and effective treatment planning require reliable, valid and responsive measures of these domains. This study aimed to assess the psychometric properties of performance based tests (PBTs) in FM and to quantify the availability of reliable, valid and responsive PBTs linked to key International Classification of Functioning, Disability and Health (ICF) categories related to functional impact. A systematic review was conducted following the PRISMA checklist, and four databases (PubMed, EMBASE, Cochrane Library and Web of Science) were searched. Eligible studies contained information on population, intervention (assessment), and outcomes (PBTs and their psychometric properties). The risk of bias and the methodological quality were assessed according to the COSMIN criteria. Twenty-two studies evaluating twenty-six PBTs were included. PBTs were linked to five ICF categories: exercise tolerance, muscle power and muscle endurance and changing basic body position and walking. The psychometric properties assessed were reliability, validity and responsiveness. The 6 min walking test was the most often assessed PBT with moderate quality of evidence for reliability, and very good methodological quality for validity. Overall, the methodological quality for reliability was rated as doubtful with very low to moderate evidence, for validity we found very good methodological quality with low to high evidence. No studies investigated criterion validity, and construct validity and responsiveness were seldom determined. Clinicians assessing FM patients should carefully select PBTs. Future research on PBTs psychometrics in FM should follow COSMIN recommendations, ensuring control of symptom variability. PERSPECTIVE: This review confirms that the current understanding of the psychometric properties of PBTs for FM patients is limited, hindered by heterogeneous tests and insufficient evidence, complicating outcome comparisons across studies. This gap underscores the need for future research to enhance methodological quality and address missing ICF categories related to FM. REGISTERED PROTOCOL AT PROSPERO: Registration number: CRD42022380709.