Phase angle and ultrasonographic muscle thickness are potential methods to assess 30-day mortality risk in older adults with hip fractures

Objectives A low-energy hip fracture is a clinical diagnosis of osteoporosis. Thus, patients with both hip fracture and sarcopenia may be classified as having osteosarcopenia, which increases the risk of death. Assessing sarcopenia in bedridden patients, often with impaired cognition, is challenging. This study evaluated whether electrical bioimpedance (BIA) and quadriceps ultrasound are associated with 30-day mortality after hip fracture. Methods Prospective cohort of people older than 60 years with proximal femur fractures due to low-impact trauma and hospitalized in a university hospital in Brazil. Body composition was assessed by BIA, including phase angle (PhA). Quadriceps femoris muscle thickness (MT) was measured by ultrasonography and adjusted for knee height squared (Kh 2 ). The combination of PhA and MT was assessed as a parameter indicative of muscle mass and quality. Statistical analysis included receiver operating characteristic (ROC) curves and adjusted Cox regression. Results A total of 133 patients were included (79% female), of whom 47% had impaired cognition; 30-day mortality was 17 (12%). Lower PhA and reduced quadriceps MT were each associated with higher 30-day mortality, even after adjustment for confounders. The composite index of rectus femoris muscle thickness (RF MT /Kh 2 ) and PhA resulted in an AUC of 0.806 (95%CI:0.679 to 0.933), with a higher discriminatory ability for mortality than single parameters: PhA: 0.742 (95%CI: 0.602 to 0.882); RF MT : 0.751 (95%CI: 0.625 to 0.876) Conclusion PhA and quadriceps MT are independent predictors of 30-day mortality in older adults with hip fractures. For hospitalized, bedridden patients who cannot perform volitional strength tests, the combination of MT and PhA may complement osteosarcopenia assessment, thereby improving the prediction of poor outcomes.