Reliability and Validity of the Persian Version of the University of California at Los Angeles (UCLA) Activity Scale in Candidates for Knee Replacement Surgery

Abstract

Objective: This study aims to translate and cross-culturally adapt the University of California at Los Angles Activity Scale (UCLA) to Iranian samples and evaluate the reliability and validity of the Persian UCLA in candidates for knee replacement surgery. Materials & Methods: In this cross-sectional study, cross-cultural adaptation was performed according to the international quality of life assessment protocol in three stages: standard forward translation, translation synthesis, and backward translation. The Persian UCLA, tegner activity scale (TAS), short-form health survey (SF-36) and international physical activity questionnaire (IPAQ) were completed by 103 participants (candidates for knee replacement surgery). The Persian UCLA questionnaire was re-completed by 66 participants in the retest session with an interval of 3-7 days. 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) in scores. To evaluate convergent validity of the Persian UCLA, its correlation with TAS, SF-36, and IPAQ was assessed using Spearman’s correlation test. The ceiling and floor effects were also calculated. Results: In the Persian version, no special changes were made and no problem or ambiguity was reported by the respondents based on a pilot study. The type of activities mentioned in the original version was not changed either and none of the participants had difficulty understanding the items. The Mean±SD of UCLA scores were 2.98±1.37 in the test phase and 2.89±1.32 in the retest phase. Psychometric tests results showed acceptable test-retest reliability of the Persian UCLA (ICC=0.96, 95% CI=0.93-0.97). Given an SDC score of 0.50 at 95% confidence interval, it can be said that if the UCLA score be above or less than 0.50, there is an improvement or decline in the activity level of patients. Based on the results of Spearman correlation test, the Persian UCLA showed a strong correlation with TAS (rs=0.71, P<0.001), a moderate correlation with IPAQ (rs=0.58, P<0.001) and physical health summary component of SF-36 (rs=0.59, P<0.001), and a weak correlation with the mental health summary component of SF-36 (rs=0.39, P<0.001). The Persian UCLA questionnaire had no ceiling or floor effects. Conclusion: The Persian version of the UCLA questionnaire has acceptable reliability and validity for Iranian candidates for knee replacement surgery.