Obesity Is Associated with Improved Early Survival but Increased Late Mortality in Surgical Patients with Sepsis: A Propensity Matched Analysis.

INTRODUCTION: While obesity is a risk factor for post-operative complications, its impact following sepsis is unclear. The primary objective of this study was to evaluate the association between obesity and mortality following admission to the surgical ICU (SICU) with sepsis.

METHODS: We conducted a single center retrospective review of SICU patients grouped into obese (n = 766, BMI ≥30 kg/m2) and non-obese (n = 574, BMI 18-29.9 kg/m2) cohorts. Applying 1:1 propensity matching for age, sex, comorbidities, SOFA, and transfer status, demographic data, comorbidities, and sepsis presentation were compared between groups. Primary outcomes included in-hospital and 90-day mortality, ICU length of stay (LOS), need for mechanical ventilation (IMV) and renal replacement therapy (RRT). P < 0.05 was considered significant.

RESULTS: Obesity associates with higher median ICU LOS (8.2 vs 5.6, p < 0.001), need for IMV (76% vs 67%, p = 0.001), ventilator days (5 vs 4, p < 0.004), and RRT (23% vs 12%, p < 0.001). In-hospital (29% vs 18%, p < 0.0001) and 90-day mortality (34% vs 24%, p = 0.0006) was higher for obese compared to non-obese groups. Obesity independently predicted need for IMV (OR 1.6, 95th CI: 1.2-2.1), RRT (OR 2.2, 95th CI: 1.5-3.1), in-hospital (OR 2.1, 95th CI: 1.5-2.8) and 90-day mortality (HR: 1.4, 95TH CI: 1.1-1.8), after adjusting for SOFA, age, sex, and comorbidities. Comparative survival analyses demonstrate a paradoxical early survival benefit for obese patients followed by a rapid decline after 7 days (logrank p = 0.0009).

CONCLUSIONS: Obesity is an independent risk factor for 90-day mortality for surgical patients with sepsis, but its impact appeared later in hospitalization. Understanding differences in systemic responses between these cohorts may be important for optimizing critical care management.

LEVEL OF EVIDENCE: III.