Comparison of simple bedside sarcopenia-related tests and their association with postoperative recovery after lumbar disc herniation surgery: a pilot study

Abstract Background Probable sarcopenia, defined by low muscle strength, is a common and potentially modifiable preoperative condition in older adults undergoing lumbar spine surgery. We evaluated how preoperative sarcopenia risk and probable sarcopenia, identified with simple bedside tests, affect postoperative recovery, and whether the available tests are interchangeable. Methods In this prospective single-center observational cohort study at a tertiary university hospital, we screened 123 consecutive adults (≥ 45 years) scheduled for elective lumbar disc herniation surgery and analysed 111. Risk of sarcopenia was screened with the SARC-F questionnaire; probable sarcopenia was assessed with absolute hand-grip strength (HGS) and the 30-s chair-stand test (30 s-CST); and clinically relevant weakness with BMI-adjusted HGS (HGS/BMI) per FNIH criteria. The primary outcomes were length of hospital stay (LOS) and time to independent ambulation over 20 m without a walking aid. We analysed length of stay in its original count form using multivariable Poisson regression with robust standard errors, adjusted for age, sex, BMI, ASA status, and diabetes. BMI was omitted from the HGS/BMI model because it is mathematically incorporated into the exposure. Threshold-based logistic models for prolonged LOS were retained as sensitivity analyses, and time to independent ambulation was analysed as a time-to-event outcome. Results All four tests were associated with worse postoperative recovery, including longer hospital stay and delayed independent walking. Agreement between the criteria was generally low (Cohen’s κ 0.237–0.315), suggesting that the tools identified somewhat different subgroups. In adjusted models, prolonged LOS was independently associated with SARC-F (adjusted incidence rate ratio [IRR] 1.17, 95% CI 1.02–1.34), the chair-stand classification (IRR 1.21, 95% CI 1.05–1.40), and BMI-adjusted HGS (IRR 1.29, 95% CI 1.08–1.53), whereas absolute HGS showed a similar effect size without reaching statistical significance (IRR 1.08, 95% CI 0.92–1.27). Conclusions Preoperative sarcopenia risk, probable sarcopenia, and clinically relevant weakness, identified using simple, radiation-free bedside tools, were associated with an adverse postoperative course after lumbar disc herniation surgery; SARC-F, the chair-stand classification, and BMI-adjusted HGS remained independently associated with longer length of stay in adjusted count models. Because the tools showed only modest agreement, they may be complementary rather than interchangeable. These preliminary findings warrant confirmation in larger, externally validated cohorts.