Association between sepsis at ICU admission and mortality in patients with ICU-acquired pneumonia: An infectious second-hit model

Purpose: We explore the hypothesis that critically ill patients developing ICU-acquired pneumonia (ICU-AP) have worse outcomes and an altered inflammatory response if their ICU admission was sepsis-related.

Methods: Prospective cohort study in two centers. Patients with ICU-AP were evaluated according to their previous exposure to sepsis at ICU-admission. Demographic variables, comorbidities, severity scores at admission and at the time of acquisition of ICU-AP, and serum biomarkers of the inflammatory response were evaluated.

Primary outcome: 90-day mortality.

Secondary outcomes: ICU and hospital length of stay, mortality at days 28 and 180, in-hospital mortality, ventilator-free days (day-28), and inflammatory response. Propensity scoring weighted the risk of previously-acquired sepsis. Multivariate analysis evaluated the risk of mortality by day-90. Sensitivity analyses evaluated the primary outcome in different subgroups.

Results: Of 341 patients enrolled, 147 had sepsis on ICU-admission. Adjusted risk of mortality at 90 days did not differ overall [hazard ratio (HR) = 0.94(CI:0.65-1.37)], nor in subpopulations with a confirmed etiology of pneumonia [HR = 0.93(CI:0.57-1.53)] or sepsis [HR = 0.91(0.54-1.55)], ventilator-associated pneumonia (VAP) [HR = 1.01(CI:0.61-1.68)], nor non-VAP ICU-AP [HR = 0.83(CI:0.40-1.71)]. No differences were found in clinical secondary outcomes, the inflammatory response was similar.

Conclusions: Previous sepsis does not appear to predispose to higher mortality nor worse outcomes in patients who develop ICU-acquired pneumonia.