Validity and reliability of the Danish version of the Short Form Brief Pain Inventory

Background: Pain is impacted by bio-psycho-social factors and is closely related to disability and poor quality of life. Therefore, a patient-reported outcome measure (PROM) is needed to capture these aspects effectively. The Short Form Brief Pain Inventory (SF-BPI) serves this purpose as a tool for pain assessment. However, the Danish translation (SFBPI-DK) has not undergone validation. Objective: Assess the validity and reliability of SFBPI-DK. Methods: In patients with spine-related pain, construct validity was tested using Confirmatory Factor Analysis (CFA) and convergent validity through correlations with EuroQol 5-domain 5-level (EQ-5D-5L), EQ-5D-5L VAS, Work Ability Score (WAS), and Insomnia Severity Index (ISI-7). Internal consistency was assessed with Cronbach's alpha. In individuals with musculoskeletal pain, test-retest reliability and Minimal Detectable Change (MDC) were evaluated. Floor and ceiling effects were reported for both groups. Results: In patients with spine-related pain (n = 329), construct validity of the SFBPI-DK was confirmed through CFA of a modified 3-factor structure. Convergent validity showed "fair" to "moderate strong" associations with EQ-5D-5L, EQ-5D-5L VAS, WAS, and ISI-7. Internal consistency was satisfactory (Cronbach's alpha 0.89-0.91). In individuals with musculoskeletal pain (n = 119), good temporal stability was demonstrated with ICCs of 0.76-0.88. The MDC for the Severity score, Interference score, and the Physical- and Affective Interference subscores were 3.37, 2.41, 3.57, and 4.01, respectively. Conclusion: The SFBPI-DK is a valid tool for assessing pain in patients with persistent spine-related pain and a reliable tool for individuals with persistent musculoskeletal pain among Danish-speaking populations.