Reliability and Validity of the Musculoskeletal Tumor Society Scoring System for the Upper Extremity in Japanese Patients

Background The Musculoskeletal Tumor Society (MSTS) scoring system developed in 1993 is a widely used disease-specific evaluation tool for assessment of physical function in patients with musculoskeletal tumors; however, only a few studies have confirmed its reliability and validity. Questions/purposes The aim of this study was to validate the MSTS scoring system for the upper extremity (MSTS-UE) in Japanese patients with musculoskeletal tumors for use by others in research. Does the MSTS-UE have: (1) sufficient reliability and internal consistency; (2) adequate construct validity; and (3) reasonable criterion validity in comparison to the Toronto Extremity Salvage Score (TESS) or SF-36? Methods Reliability was performed using test-retest analysis, and internal consistency was evaluated with Cronbach’s alpha coefficient. Construct validity was evaluated using a scree plot to confirm the construct number and the Akaike information criterion network. Criterion validity was evaluated by comparing the MSTS-UE with the TESS and SF-36. Results The test-retest reliability with intraclass correlation coefficient (0.95; 95% CI, 0.91–0.97) was excellent, and internal consistency with Cronbach’s α (0.7; 95% CI, 0.53–0.81) was acceptable. There were no ceiling and floor effects. The Akaike Information Criterion network showed that lifting ability, pain, and dexterity played central roles among the components. The MSTS-UE showed substantial correlation with the TESS scoring scale (r = 0.75; p < 0.001) and fair correlation with the SF-36 physical component summary (r = 0.37; p = 0.007). Although the MSTS-UE showed slight correlation with the SF-36 mental component summary, the emotional acceptance component of the MSTS-UE showed fair correlation (r = 0.29; p = 0.039). Conclusions We can conclude that the MSTS is not an adequate measure of general health-related quality of life; however, this system was designed mainly to be a simple measure of function in a single extremity. To evaluate the mental state of patients with musculoskeletal tumors in the upper extremity, further study is needed.