Measurement properties of the Swedish Brief Pain Coping Inventory-2 in patients seeking primary care physiotherapy for musculoskeletal pain.

OBJECTIVES

This study aimed to evaluate the validity and reliability of the two subscales of a Swedish version of the Brief Pain Coping Inventory-2 (BPCI-2:SWE) in a population of patients seeking primary care physiotherapy for musculoskeletal pain (MSKP). The BPCI-2 is a patient-reported outcome measure (PROM) originally developed to measure traditional pain management strategies (TPMS) and psychological flexibility (PF) in populations with chronic pain.

METHODS

This study followed guidance from the "COnsensus based Standards for the selection of health Measurement INstruments-group" and the stages described by Beaton. The BPCI-2 was translated and cross-culturally adapted from English to Swedish. The BPCI-2:SWE's content validity was evaluated using the face-validity index and qualitative content analysis of semi-structured interviews in a cohort of 13 patients seeking primary care physiotherapy for MSKP. The BPCI-2:SWE's construct validity, floor and ceiling effects, reliability, and measurement error were evaluated using a test-retest design in a cohort of 124 patients seeking primary care physiotherapy for MSKP.

RESULTS

The BPCI-2:SWE had excellent content validity, but patients' experiences indicated that the scoring method may benefit from amendment. The PF subscale demonstrated good construct validity on hypothesis testing. However, the TPMS subscale did not reach the a priori threshold for good construct validity, correlating positively with pain intensity and demonstrating low correlation with all other PROMs. Neither subscale demonstrated floor or ceiling effects. The PF subscale had moderate, and the TPMS subscale had good, test-retest reliability. Measurement error was relatively high for both subscales at the individual patient level but low at the group level.

CONCLUSIONS

The BPCI-2:SWE is comprehensible and relevant within a Swedish primary care context. The BPCI-2:SWE demonstrated adequate measurement properties for use as an outcome measure in research studies, but future research should further evaluate the BPCI-2:SWE's reliability, responsiveness, and prognostic utility.