Further validation of the Toronto extremity salvage score for lower extremity soft tissue sarcoma based on Finnish patients

The most widely used patient-reported outcome (PRO) measure for soft tissue sarcoma (STS) patients is the Toronto Extremity Salvage Score (TESS). The aim of the study was to validate and test the reliability of the TESS for patients with lower extremity STS based on Finnish population data. Patients were assessed using the TESS, the QLQ-C30 Function and Quality of life (QoL) modules, the 15D and the Musculoskeletal tumour Society (MSTS) score. The TESS was completed twice with a 2- to 4-week interval. The intraclass correlation coefficient (ICC) was used for test-retest reliability. Construct validity was tested for structural validity and convergent validity. Altogether 136 patients completed the TESS. A ceiling effect was noted as 21% of the patients scored maximum points. The ICC between first and second administration of the TESS was 0.96. The results of exploratory factor analysis together with high Cronbach's alpha (0.98) supported a unidimensional structure. The TESS correlated moderately with the MSTS score (rho = 0.59, p< 0.001) and strongly with the mobility dimension in the 15D HRQL instrument (rho = 0.76, p < 0.001) and the physical function in QLQ-C30 (rho = 0.83, p< 0.001). The TESS instrument is a comprehensive and reliable PRO measure. The TESS may be used as a validated single index score, for lower extremity STS patients for the measurement of a functional outcome. The TESS seems to reflect patients’ HRQoL well after the treatment of lower extremity soft tissue sarcomas.