RESUMO
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 <.01]) and accepting 75% of prior hypotheses. The minimal clinically important change was 6.96 points. No floor or ceiling effects were detected. CONCLUSIONS: The KNAP-SP, with robust psychometric properties and successful adaptation and validation, is a valuable tool for assessing pain knowledge and attitudes among Spanish-speaking physiotherapists.