Psychometric properties of the Swedish version of the Functional Disability Inventory

Abstract

Chronic or recurrent pain is a common experience in children and adolescents. One questionnaire that is frequently used to assess pain-related disability is the Functional Disability Inventory (FDI). The aim of this study was to evaluate the psychometric properties of the Swedish version of the FDI. The patient group consisted of 30 patients, 8–17 years old. The comparison group consisted of 78 pupils, 8–17 years old. Reliability was assessed using Cronbach's alpha and intraclass correlation (ICC). Validity was assessed in terms of construct validity and face validity. To assess construct validity, Spearman's rho was used. Internal consistency reliability was high, with Cronbach's α = 0.90. Similarly, test–retest reliability was good, with an ICC of 0.90 (95% confidence interval 0.78–0.95). Concerning interrater reliability, the result was good, with an ICC of 0.67. Construct validity correlations, assessed using Spearman's rho, were significant. Most participants (85.7%) did not report any areas in their everyday lives where they experienced any disabilities not covered in the FDI, indicating acceptable face validity. In this context and used in this population, the results indicate that the FDI is a reliable and valid questionnaire for assessing pain-related disability in children and adolescents.