Association between fat-free mass index and severe locomotive syndrome in patients with cancer: sex-specific cutoff values

Background Locomotive syndrome (LS) is a clinical condition used to describe reduced mobility caused by musculoskeletal dysfunction and is highly prevalent among patients with cancer. The fat-free mass index (FFMI) is an indicator of nutritional status and muscle mass, and has been associated with malnutrition and prognosis in this population. This study investigated the relationship between FFMI and LS in patients with cancer and determined sex-specific FFMI cutoff values associated with severe LS. Methods This study included patients hospitalized for cancer treatment who were referred for rehabilitation therapy. Patient characteristics, laboratory data, body composition, and grip strength were collected. LS was assessed using the stand-up test, two-step test, and 25-Geriatric Locomotive Function Scale. FFMI was measured using bioelectrical impedance analysis. Results Overall, 144 patients (102 men and 42 women; mean age, 63.9 ± 15.8 years) were analyzed. Ordinal logistic regression analysis demonstrated that FFMI was independently associated with LS severity (odds ratio [OR], 0.597; 95% confidence interval [CI], 0.434–0.821). The optimal FFMI cutoff values associated with severe LS (grade ≥ 2) were 16.99 kg/m² in men and 15.25 kg/m² in women, with areas under the curves of 0.806 (95% CI, 0.720–0.890) and 0.760 (95% CI, 0.596–0.925), respectively. Conclusions FFMI was associated with mobility function in patients with cancer. The proposed sex-specific cutoff values may help identify patients with impaired mobility who could be considered for referral to rehabilitation therapy.