Risk factors for ventilator‐associated lower respiratory tract infection in COVID‐19, a retrospective multicenter cohort study in Sweden

Abstract

AbstractBackgroundVentilator‐associated lower respiratory tract infections (VA‐LRTI) increase morbidity and mortality in intensive care unit (ICU) patients. Higher incidences of VA‐LRTI have been reported among COVID‐19 patients requiring invasive mechanical ventilation (IMV). The primary objectives of this study were to describe clinical characteristics, incidence, and risk factors comparing patients who developed VA‐LRTI to patients who did not, in a cohort of Swedish ICU patients with acute hypoxemic respiratory failure due to COVID‐19. Secondary objectives were to decipher changes over the three initial pandemic waves, common microbiology and the effect of VA‐LTRI on morbidity and mortality.MethodsWe conducted a multicenter, retrospective cohort study of all patients admitted to 10 ICUs in southeast Sweden between March 1, 2020 and May 31, 2021 because of acute hypoxemic respiratory failure due to COVID‐19 and were mechanically ventilated for at least 48 h. The primary outcome was culture verified VA‐LRTI. Patient characteristics, ICU management, clinical course, treatments, microbiological findings, and mortality were registered. Logistic regression analysis was conducted to determine risk factors for first VA‐LRTI.ResultsOf a total of 536 included patients, 153 (28.5%) developed VA‐LRTI. Incidence rate of first VA‐LRTI was 20.8 per 1000 days of IMV. Comparing patients with VA‐LRTI to those without, no differences in mortality, age, sex, or number of comorbidities were found. Patients with VA‐LRTI had fewer ventilator‐free days, longer ICU stay, were more frequently ventilated in prone position, received corticosteroids more often and were more frequently on antibiotics at intubation. Regression analysis revealed increased adjusted odds‐ratio (aOR) for first VA‐LRTI in patients treated with corticosteroids (aOR 2.64 [95% confidence interval [CI]] [1.31–5.74]), antibiotics at intubation (aOR 2.01 95% CI [1.14–3.66]), and days of IMV (aOR 1.05 per day of IMV, 95% CI [1.03–1.07]). Few multidrug‐resistant pathogens were identified. Incidence of VA‐LRTI increased from 14.5 per 1000 days of IMV during the first wave to 24.8 per 1000 days of IMV during the subsequent waves.ConclusionWe report a high incidence of culture‐verified VA‐LRTI in a cohort of critically ill COVID‐19 patients from the first three pandemic waves. VA‐LRTI was associated with increased morbidity but not 30‐, 60‐, or 90‐day mortality. Corticosteroid treatment, antibiotics at intubation and time on IMV were associated with increased aOR of first VA‐LRTI.