RESUMO
STUDY DESIGN: Prospective observational study. PURPOSE: To test the face validity, content validity, feasibility, internal consistency, reliability, and test-retest reliability of the Arabic version of the Copenhagen Neck Functional Disability Scale (CNFDS). OVERVIEW OF LITERATURE: CNFDS is a clinical evaluation tool that accurately reflects the patient's perception regarding his/her functionality with existing cervical pain. This study aimed to investigate the validity and reliability of the Arabic version of the CNFDS in measuring the disability level in chronic neck pain patients. METHODS: Seventy-four patients with neck pain were recruited, and 135 sheets (test and retest sheets) were completed by patients; two expert panels (each comprising ten experts) participated in this study. Arabic translation (forward translation), development of the preliminary translated version, English translation (backward translation), development of the prefinal version, and testing of the prefinal version was performed by experts; thereafter, the final version was tested on patients. Index of clarity, expert proportion of clearance, index of content validity (CVI), expert proportion of relevance, descriptive statistics, missed item index, Cronbach's alpha, and Spearman's rank correlation coefficient were used for statistical analyses. RESULTS: The study revealed that the scale index of clarity was 86.84%, scale CVI was 99.33%, scale-level content validity index (universal agreement method) was 99.33%, 99.15% of the scale items were filled in all sheets, the scale was answered in less than 3 minutes in about 75% cases, Cronbach's alpha was 0.856 (0.796, 0.905), and all Spearman's correlations between the test and retest results were statistically significant. CONCLUSIONS: The Arabic version of the CNFDS has adequate validity and reliability for the measurement of the disability level in chronic neck pain patients.