Reliability and Validity of the Persian-Version of the University of California, Los Angeles (UCLA) Questionnaire in Iranian Candidates for Knee Replacement Surgery

Objective: To translate and cross-culturally adapt the University of California at Los Angles (UCLA) activity score to a Persian-version (UCLA-P) and evaluate the reliability and validity of the UCLA-P for Iranian patients (n=103) who were candidate for knee replacement surgery. Methods: In this methodological study, cross-cultural adaptation was performed according to the international quality of life assessment (IQOLA) in three stages: standard forward translation, synthesis and backward translation. Then, four questionnaires of UCLA, Tegner, short-form 36 health survey (SF-36) and international physical activity questionnaire (IPAQ) were completed by 103 participants. The UCLA-P questionnaire was re-completed by 66 participants in the retest session with time interval of 3 to 7 days between sessions. An intra-class correlation coefficient (ICC) was used to evaluate test-retest reliability. The standard error of measurement (SEM) was used to determine smallest detectable change (SDC). To evaluate construct validity of UCLA-P compared to similar and dissimilar concepts of Tegner, SF-36, and IPAQ, the Spearman’s rank correlation coefficient was used. The Ceiling and floor effects was used to evaluate content validity of UCLA-P. Results: During the process of Forward_Backward translation (Persian_English) no special changes were made by the translators and no problem or ambiguity was reported by the respondents in the pilot study. The type of sports mentioned in the original questionnaire was not changed either. None of the participants complained about the difficulty of understanding the content of the questionnaire options. In order to evaluate the test-retest reliability, the mean and standard deviation of the responses of 66 participants in the test session were 2.98±1.37 and in the retest session during the next 3 to 7 days were 2.89±1.32. Psychometric tests on the test-retest reliability for the Persian-version of the UCLA questionnaire, with ICC = 0.96 (CI = 0.93-97-97) showed acceptable results. Given an SDC score of 0.50, clinically with 95% confidence, it can be said that if the UCLA activity level score goes above or below 0.50, there is an improvement or deterioration in the activity level of these patients. By observing the results of Spearman correlation analysis, all hypotheses of this study were confirmed. The results of construct validity showed a strong correlation between UCLA-P and Tegner (rs = 0.71, p <0.001). In addition, UCLA-P showed a moderate correlation with IPAQ (rs = 0.58, p <0.001) and physical component of SF-36 (rs = 0.59, p <0.001). Compared to physical component of SF-36, there was a lower correlation between UCLA-P and the psychological component of SF-36 (rs = 0.39, p < 0.001). In this study, the response rate to item number 1 of the questionnaire (lowest activity level), which indicates the percentage of floor effect, was 4.9%, and the response rate to item number 10 of the questionnaire (highest activity level), which reflects the effect of the ceiling, was zero. Therefore, the UCLA-P questionnaire has no ceiling and floor effects and indicates the acceptable content validity of this questionnaire. Conclusion: The Persian version of the UCLA questionnaire that have acceptable reliability and validity seems to be suitable for Iranian candidates for knee surgery.