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Published on: July 7, 2023
Construct validity, reliability, and sensitivity of proxy-reported pain interference in individuals with cerebral
Breanne J Byiers1, Serena Chan2, Frank J Symons1
1Department of Educational Psychology, University of Minnesota, 56 East River Rd, Minneapolis, MN 55455, USA.
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Chronic pain is prevalent among individuals with cerebral palsy (CP), yet its assessment is complicated by communication and cognitive challenges. The Modified Brief Pain Inventory (mBPI), adapted for proxy reporting (mBPI-P), offers a multidimensional approach to evaluating pain interference. This study aimed to validate the mBPI-P in individuals with CP, relying on proxy-report, by examining its factor structure, reliability, and sensitivity to clinical intervention. Two studies were conducted. Study 1 assessed the construct validity of the 7-, 10-, and 12-item versions of the mBPI-P using confirmatory factor analysis in a sample of 250 individuals with CP and chronic pain. Study 2 evaluated test-retest reliability and sensitivity to corticosteroid joint injections in a separate, smaller, cohort using multi-level modeling and linear mixed-effects analysis. The 7-item two-factor model demonstrated the best fit (CFI = .979, RMSEA = .083) and strong internal consistency (α =.900). Total scores showed moderate correlations with pain severity and duration, and negligible correlation with physical disability, supporting concurrent and divergent validity. In Study 2, test-retest reliability was excellent (RkF = .97). Sensitivity analysis revealed greater reductions in mBPI-P scores following joint injections compared to a matched control group, though pain scores declined over time in both groups. Findings support the use of the 7-item mBPI-P as a reliable and valid tool for assessing pain interference in individuals with CP. Its strong psychometric properties support its use in clinical contexts and research to measure the multidimensionality of pain, assess changes in pain over time, and determine treatment efficacy. PERSPECTIVE: This article presents the psychometric properties of a widely used pain interference scale for use among caregivers of individuals with cerebral palsy. Reducing the number of items included in the scale may improve its measurement properties. The reduced version of the scale shows good psychometric properties, supporting its use.
