The prevalence of sarcopenia in adult spinal deformity patients differs significantly across measurement methods

Introduction: Sarcopenia has been associated with adverse outcomes after spine surgery. A major limitation to this research is that studies use many different criteria used to define sarcopenia. Thus, it remains unclear what the true prevalence of sarcopenia is in the adult spinal deformity (ASD) population. We sought to measure and compare the baseline prevalence of sarcopenia in ASD patients using 3 methods of measurement included in the Sarcopenia Definitions and Outcomes Consortium (SDOC) consensus criteria.

Methods: ASD patients at a single tertiary-care center were assessed preoperatively for grip strength and gait speed. Bioimpedance analysis (BIA) was performed using the Inbody970 Body Composition Analyzer (Inbody, USA) to determine Skeletal Muscle Index (SMI), which is appendicular skeletal muscle mass (ASM) divided by height2. The following SDOC-proposed cutoff points for sarcopenia were utilized: grip strength < 35.5kg for men and < 20.0kg for women, gait speed < 0.8m/s, and SMI of < 7.26kg/m2 for men, < 5.45kg/m2 for women. Differences in sarcopenia prevalence by each measurement method were evaluated using Chi-square analysis.

Results: Between 2023-2024, 97 ASD patients were evaluated for sarcopenia preoperatively. Sixty-four (66.0%) were female. The average age did not differ significantly between women and men (65.2 vs. 61.9 years, respectively, P=0.26, Student’s t test). For grip strength, 34 of 66 (53.1%) women and 20 of 33 (60.1%) men met the sarcopenia cutoff. For gait speed, 56 of 60 (93.3%, 4 patients excluded based on inability to ambulate) women and 29 of 33 (87.8%) men had a gait speed < 0.8m/s. In contrast, based on BIA data, 3 of 64 (4.7%) women had a SMI < 5.45 and 2 of 33 (6.1%) men had a SMI < 7.26. Chi-square analysis showed the proportion of sarcopenic individuals differed significantly within male (P < 0.0001) and female (P < 0.0001) by measurement method.

Conclusion : The prevalence of sarcopenia in the preoperative ASD patients varied from 4.7-93.3% of women and 6.1-87.8% of men based on 3 methods put forth by SDOC consensus criteria. These results highlight the need for a standardized diagnostic criterion for sarcopenia in ASD patients.