At univariable analysis diabetes (HR 1.80, 95% CI 1.07–3.04, p = 0.03), age (HR 1.05, 95% CI 1.02–1.08, p = <0.001), obesity (HR 1.99, 95% CI 1.15–3.45, p = 0.01), WBC count (HR 1.06, 95% CI 1.03–1.10, p<0.001), neutrophils count (HR 1.07, 95% CI 1.03–1.11, p<0.001), high-sensitivity C-reactive protein value (HR 1.03, 95% CI 1.00–1.05, p = 0.02), procalcitonin (HR 1.04, 95% CI 1.01–1.06, p = 0.002), SOFA score (HR 1.78, 95% CI 1.57–2.02, p<0.001), lactate (HR 1.02, 95% CI 1.00–1.04, p = 0.02), PaO2/FiO2 (HR 0.99, 95% CI 0.98–0.99, p<0.001) were associated with 28-day mortality. Here, CRP is linked to obesity due to melanocortin 4 receptor deficiency.