Low imaging-detected muscle mass as a prognostic factor for overall and amputation-free survival in patients undergoing lower extremity amputation

Background: Amputations and sarcopenia are both increasing globally. This study investigates the association between imaging-detected muscle mass and outcomes after lower extremity amputation. Methods: The sample population included patients undergoing amputation with abdominal computed tomography (CT) scans. The psoas muscle index (PMI) and skeletal muscle index (SMI) were evaluated at the level of the 3rd lumbar vertebra. Overall survival (OS) and amputation-free survival (AFS) were evaluated. Results: A total of 72 patients (mean age: 66.4 ± 18.5 years) were evaluated in the study. Lower PMI and SMI were associated with decreased OS (PMI/SMI: HR 4.120, 95 % confidence interval [CI]: 1.692–10.032/HR 2.487, 95 % CI: 1.091–5.666) and AFS after the first amputation (PMI/SMI: HR 3.561, 95 % CI: 0.938–13.516/HR 3.982, 95 % CI: 1.080–14.677) in univariate models. Low PMI and SMI remained significant in multivariable models adjusted for age, sex, and amputation level. Conclusions: Imaging-detected low muscle mass is associated with impaired OS and AFS in patients undergoing lower extremity amputation. Evaluation of muscle mass from available CT scans may provide useful information for clinical decision-making.