Marx Activity Rating Scale: Italian translation, validation and cross-cultural adaptation

BACKGROUND: Currently, in sport and in the orthopedic field, the presence of objective, reliable and validated measurement tools is essential; they allow us to objectify the athlete’s or patient’s state of health and establishing the best rehabilitation treatment programme. However, most of them are designed to quantify symptoms and/or functional disability only, while Functionality and level of activity assessed distinctly and separately. For this reason, the objective was to adapt the Marx Activity Rating Scale into Italian language. METHODS: The original questionnaire in English was translated according to the guidelines. We included patients with various knee injuries and disorders. The statistical was conducted with the use of Spearman’s correlation to assess convergent validity and reproducibility, Cronbach’s alpha to assess internal consistency, and intraclass correlation (ICC) for test-retest reliability. A factor analysis was performed, and content validity was determined by the presence of floor and ceiling effects. RESULTS: Ninety patients completed the questionnaire and 46 of them completed the retest too. Sampling was adequate (KMO=0.782). Significant correlations were found between MARS and IKDC (Spearman r=0.804, P<0.01) and CKRS (Spearman r=0.600, P<0.01). Cronbach’s alpha was 0.853 at the first administration of the questionnaire and 0.840 at the retest. The intraclass correlation coefficient was 0.925. There were no floor and ceiling effects. CONCLUSIONS: Statistically significant results (ICC 0.925) emerged from the analysis of the collected data, demonstrating that the Italian version of the MARS has excellent psychometric properties; this makes it a valid and reliable tool to assess the level of activity in subjects suffering from different knee problems.