Psychometric evaluation of the Hamilton Inventory to evaluate signs and symptoms in patients with Complex Regional Pain Syndrome (CRPS)

BACKGROUND: Complex Regional Pain Syndrome (CRPS) is a debilitating condition with profound physical and psychological impacts, necessitating comprehensive assessment tools for effective evaluation. PURPOSE: This study aimed to validate the Persian version of the Hamilton Inventory for Complex Regional Pain Syndrome (HI-CRPS) and assess its reliability and validity in individuals diagnosed with CRPS. STUDY DESIGN: A cross-sectional clinical measurement study evaluated the Persian version of HI-CRPS. METHODS: A sample of 64 individuals diagnosed with CRPS from pain and hand surgeon clinics completed the Persian versions of the patient-reported (PR-HI-CRPS) and clinicians based (CB-HI-CRPS). Test-retest reliability was assessed after 1 week, and responsiveness was measured after 3 months. Baseline scores, ceiling effects, internal consistency (Cronbach's alpha), and construct validity (correlations with related measures) were examined. Effect sizes and standardized response means (SRM) were calculated to gauge responsiveness. RESULTS: Baseline scores for PR-HI-CRPS and CB-HI-CRPS were 77.8 and 14.9, respectively. Around 18% of PR-HI-CRPS and 16% of CB-HI-CRPS respondents exhibited ceiling effects. Internal consistency for PR-HI-CRPS (Cronbach's alpha: 0.71-0.91) and CB-HI-CRPS (alpha: 0.90) was satisfactory. PR-HI-CRPS (ICC: 0.86) and CB-HI-CRPS (ICC: 0.97) showed robust test-retest reliability. Construct validity was confirmed by significant correlations between PR-HI-CRPS subscales and related measures (p < 0.01). Structural validity was confirmed by confirmatory factor analysis. PR-HI-CRPS displayed an effect size of 0.79 and a standardized response mean (SRM) of 0.88. CONCLUSIONS: The Persian version of the HI-CRPS demonstrated satisfactory internal consistency, test-retest reliability, construct validity, and responsiveness. It can be relied upon to assess CRPS symptoms, functional limitations, and psychosocial impacts.