Critical appraisal of patient-reported and clinician-reported outcome measures assessing functional outcomes in lower extremity bone sarcoma patients-a COSMIN-based systematic review

PURPOSE: Local therapy for bone sarcoma often significantly impacts patients' physical abilities and participation in daily life, which underscores the need for accurate assessment of these outcomes to guide optimal care. This study aims to 1) evaluate the measurement properties of eight patient- and clinician-reported outcome measures identified in a recent systematic review (2024) as being used more than once in this population, and 2) recommend the most suitable instruments for evaluation in clinic and research. METHODS: We searched MEDLINE and Embase in July 2024 for studies assessing the development and/or measurement properties of the original version of the Baeck equestionnaire, Functional Mobility Assessment, Karnofsky Performance Status, Mankin score, MusculoSkeletal Tumor Society 1987 and 1993-Lower extremity (LE)scores, Reintegration to Normal Living (RNL) Index and Toronto Extremity Salvage Score (TESS) - LE. Full text availability was required. Measurement instruments were evaluated using COSMIN guidelines (July 2024 - January 2025). RESULTS: Seventy-three articles evaluating measurement properties of one of the eight instruments were included. The Baecke questionnaire, RNL Index and TESS-LE had clearly defined constructs of which only the RNL Index and TESS-LE demonstrated sufficient overall content validity (low- and moderate-quality evidence). The remaining instruments lacked clear construct definitions, resulting in indeterminate or insufficient content validity, and therefore cannot be recommended for use. Structural validity of the TESS-LE was inconsistent leading to indeterminate internal consistency, currently preventing its recommendation. Additionally, the evidence supporting sufficient measurement properties of the RNL Index was too limited to justify its use. CONCLUSION: A clearly defined construct is the cornerstone of a measurement instrument and was lacking in most cases. The TESS-LE and RNL Index show promise due to their sufficient content validity, but require further refinement before they can be recommended as standard instruments to assess physical abilities and participation in daily life in bone sarcoma patients. Advancing measurement of these outcomes requires comprehensive validation and refinement of existing instruments to overcome their current limitations, or the development of new, reliable, and valid instruments tailored to this population. REGISTRATION: Study protocol registration in the PROSPERO database:CRD42022353668.