Impact of Body Composition Status on 90-Day Mortality in Cancer Patients with Septic Shock: Sex Differences in the Skeletal Muscle Index.

Abnormalities in body composition are associated with poor prognosis in cancer patients. We investigated the association between body composition and 90-day mortality in cancer patients who developed septic shock. We included consecutive septic shock patients with active cancer from 2010 to 2017. The muscle area at the level of the third lumbar vertebra was measured by computed tomography upon emergency department admission and adjusted by height squared, yielding the Skeletal Muscle Index (SMI). Hazard ratios (HRs) and 95% confidence intervals (CIs) for 90-day mortality were estimated using a Cox proportional hazards model. Among 478 patients, the prevalence of muscle depletion was 87.7%. Among markers of body composition, the SMI only differed significantly between non-survivors and survivors (mean, 35.48 vs. 33.32 cm2/m2; P = 0.002) and was independently associated with lower 90-day mortality (adjusted HR, 0.970; P = 0.001). The multivariable-adjusted HRs (95% CI) for 90-day mortality comparing quartiles 2, 3, and 4 of the SMI to the lowest quartile were 0.646 (0.916-1.307), 0.620 (0.424-0.909), and 0.529 (0.355-0.788), respectively. The associations were evident in male patients, but not in female patients. The SMI was independently associated with 90-day mortality in cancer patients with septic shock. The graded association between the SMI and 90-day mortality was observed in male patients.