Measurement Properties of the Functional Rating Index: A systematic Review and Meta-analysis.

Study Design. A systematic review and meta-analysis. Objective. To assess the measurement properties of the Functional Rating Index (FRI) and determine whether its measurement properties are comparable with other region-specific questionnaires. Summary of Background Data. In addition to low back pain (LBP) and neck pain (NP), multiregion spinal pain (SP) is a common problem with a considerable prevalence in the general population. The FRI was built to assess physical functioning in patients with SP. However, a systematic review assessing evidence of its measurement properties in separated populations and a comparison with other questionnaires regarding each measurement property is lacking. Methods. Articles concerning the FRI's measurement properties or head-to-head comparison with other questionnaires on measurement properties were obtained from MEDLINE, Embase, CINAHL, and PsycINFO. Two reviewers independently reviewed the articles, extracted data, and conducted the methodological quality assessment. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist was used to assess the methodological quality of the included studies. Results. A total of 18 studies evaluating the FRI's measurement properties, including seven that carried out head-to-head comparisons in at least one measurement property with other questionnaires, were included in the current review. Our findings show strong positive evidence for structural validity and internal consistency in patients with SP and LBP. Evidence for most of the FRI's measurement properties is limited, conflicting, or even unknown. The current evidence shows that the FRI is comparable with both the Oswestry Disability Index and the Neck Disability Index in responsiveness. However, relevant information about the majority of the other measurement properties is lacking. Conclusion. Our finding suggests that clinicians and researchers should use the FRI with caution until there are more studies with high methodological quality that support the view that it is positive in all measurement properties, especially in regard to patients with multiregion SP.