Assessing the Utility of Frailty and Sarcopenia in Spinal Oncology: A Comprehensive Systematic Review and Critical Analysis

Introduction: Increased frailty and sarcopenia predict worse clinical outcomes among patients undergoing spinal surgery for degenerative and deformity-related conditions; however, this association is less clear in the context of spinal oncology. Here we sought to: (1) appraise the clinimetric properties of these tools; and (2) summarize the application of these tools in the context of risk stratification and outcome prognostication.

Methods: The AO Spine Knowledge Forum Tumor group conducted a systematic review according to 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and CINAHL were searched from January 1st, 2000, until June 2022. Study characteristics, frailty tools, and measures of sarcopenia were recorded. Component domains, individual items, cut off values, and measurement techniques were also collected. Clinimetric assessment of measurement tools was performed according to the Consensus-based Standards for Health Measurement Instruments (COSMIN).

Results: Twenty-two studies were included, accounting for 42,514 patients. Most studies (91%) were retrospective. Seventeen (77%) studies utilized tools to measure frailty. The three most employed frailty tools employed were the Metastatic Spine tumor Frailty Index (MSTFI; 7 studies), Modified Frailty Index-11 (mFI-11; 5 studies), and the mFI-5 (4 studies). Eight (36%) studies used various measures of sarcopenia; the three most common were the L3-Total Psoas Area (TPA)/Vertebral Body Area (VBA) (three studies), the L3-TPA/Height2 (2 studies), and the L3-Spinal Muscle Index (L3-Cross-Sectional Muscle Area/Height2; two studies). All measures of frailty and sarcopenia lacked or had uncertain content and construct validity. All measures of frailty were objective except the Johns-Hopkins Adjusted Clinical groups. All tools were feasible except the Hospital Frailty Risk Score (HFRS). Positive predictive validity was observed for the HFRS (2 of 2 studies), and in select studies employing the mFI-5 (2 of 4 studies), MSTFI (2 of 7 studies), and L3-TPA/VBA (1 of 3 studies). All other sarcopenia measures lacked or had uncertain predictive validity.

Conclusion : Existing tools for evaluating frailty and sarcopenia among patients undergoing surgery for spinal tumors suffer from poor clinimetric properties. There remains a need for a clinimetrically robust tool for stratifying risk and predicting clinical outcomes in this patient population.