Cross-cultural adaptation and psychometric evaluation of the Spanish version of the Knowledge and Attitudes of Pain questionnaire (KNAP) in physiotherapists

Background: Healthcare providers’ attitudes and beliefs can influence how patients with persistent musculoskeletal pain are treated. A biopsychosocial approach is more effective than a purely biomedical approach. Ensuring healthcare professionals have appropriate pain science education (PSE) is essential for successful treatment outcomes. Objective: To validate the Spanish version of the Knowledge and Attitudes of Pain (KNAP-SP) questionnaire among Spanish physiotherapists and students and analyze its psychometric properties. Methods: From May to October 2022, two independent teams adapted the KNAP questionnaire from English to both European and Hispanic-Spanish. A cross-sectional validation study was conducted with 517 physiotherapists examining internal consistency (Cronbach’s alpha), structural validity (exploratory factor analysis), and construct validity (hypothesis testing). Longitudinal analyses assessed test–retest reliability (intraclass correlation coefficient [ICC2,1; n = 63]) and responsiveness following a PSE intervention using Receiver Operating Characteristic (ROC) curve analysis and hypothesis testing (n = 70). Results: The KNAP-SP showed strong internal consistency [overall α coefficient = 0.86; domain 1 (α = 0.82); domain 2 (α = 0.70)], explaining 32.3% of the variance. Construct validity was supported by 75% of the hypotheses. Test–retest reliability was high (ICC2,1 = 0.84). KNAP-SP’s responsiveness was confirmed by ROC analysis (area under the curve [AUC] = 0.87 [95% CI: 0.79–0.96, p-value