Validation and Psychometric Properties of the Spanish Version of King's Parkinson's Disease Pain Scale

Objective: To assess the psychometric properties of the Spanish King's Parkinson's Disease Pain Scale (KPPS). Design: A descriptive transversal study at a Spanish hospital. Methods: Fifty-three Parkinson's disease (PD) patients suffering from otherwise explained pain (34 females, age = 63.42 ± 10.52 years, time with disease = 7.25 ± 4.65 years) were evaluated by the KPPS, Brief Pain Inventory (BPI), two Pain Pressure Thresholds (PPTs), Widespread Mechanical Hyperalgesia (WMH), and Conditioned Pain Modulation (CPM). A retest of the KPPS was performed 7-15 days later. Internal consistency, test-retest reliability (intraclass correlation coefficient (ICC)), measurement error, factor structure, and criterion/convergent validity were assessed. Results: Internal consistency of the Spanish KPPS was acceptable (Cronbach's alpha = 0.77). The mean test and retest total KPPS scores were similar (test = 34.83 ± 23.50 points, retest = 35.87 ± 26.23 points), and test-retest reliability was good (ICC = 0.85, 95% CI = 0.75-0.91). Standard error of measurement (SEM) was 9.1 points and smallest detectable change (SDC) was 25.22 points. The sampling adequacy was not sufficient to perform factor analysis. The total KPPS score was not correlated to the BPI intensity subscale (r = 0.18, p=0.19), but it was moderately and positively correlated to the interference subscale (r = 0.43, p=0.001). The total KPPS was moderately and negatively correlated to both the remote PPT (r = -0.4, p=0.003) and WMH (r = -0.38, p=0.005). No statistical correlations were found with local PPT or CPM. Conclusion: The present study provides evidence that the Spanish KPPS effectively measures pain in individuals with PD, with its total score demonstrating good reliability, minimal measurement error, and adequate criterion and convergent validity.