Risk factors and outcomes of ventilator-associated pneumonia in COVID-19 patients: a propensity score matched analysis

Abstract

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Dear Editor Mechanically ventilated patients with coronavirus disease (COVID-19) may be at an increased risk of developing ventilator-associated pneumonia (VAP). Our aim was to describe the clinical characteristics, risk factors, and outcomes associated with VAP in critically ill COVID-19 patients. In this single-center cohort study, all adult patients with laboratory-confirmed COVID-19, based on the detection of viral sequences by real-time reverse-transcription polymerase chain reaction, who needed mechanical ventilation (MV) between March 1, and April 30, 2020 were included. The local ethics committee approved this study and waived the need for informed consent due to the observational nature of the study. VAP was defined according to the current American Thoracic Society/ Infectious Diseases Society of America guidelines criteria [1]. Differences between quantitative variables were assessed by Student t-test or Mann–Whitney U-test. Chi-square or Fisher ́s exact tests were used to analyze categorical data. To determine which variables were independently associated with VAP, a logistic regression analysis was performed, including the variables with p < 0.1 in the univariate analysis. To assess the influence of VAP in outcomes and account for inter-group imbalances of baseline characteristics, we conducted a propensity score matching including those variables with p < 0.1 in the univariate analysis. In all cases, 1:1 matching without replacement was used with a caliper 0.2 standard deviation of logit of the propensity score and with the nearest neighbor method. In the matched cohorts, differences in the categorical variables were analyzed using McNemar’s test, and differences in continuous variables were determined using paired t-test or Wilcoxon signed-rank test, as appropriate. All statistical analyses were performed using the Stata Statistical Software 14 (StataCorp 15. College Station, TX: StataCorp LP) and R, version 3.6.3 (R project for Statistical Computing, http:// www.Rproje ct. org). Of the 353 patients admitted to the intensive care unit (ICU) during the study period, 250 (70.8%) required invasive MV (Table 1). VAP occurred in 100 (40%) of the mechanically ventilated patients. Of these, 78 were confirmed by a positive quantitative culture and 22 were defined by clinical criteria and a purulent respiratory sample. Median time to the diagnosis of VAP was 13 (8–20) days, with only 11 developing VAP within the first 96 h of admission. Antibiotic treatment was adequate in 89% of the cases. Admission to an open ICU (contingency unit without physical barriers between patients) (odds ratio [OR], 1.85; 95% confidence interval [CI], [1.04–3.33]; p = 0.037), higher Sequential Organ Failure Assessment score (OR 1.55; 95% CI [1.21–2.00]; p = 0.001), corticosteroid treatment (OR 3.26; 95% CI [1.78–5.97]; p < 0.001) and treatment with tocilizumab (OR 1.85; 95% CI [1.02–3.38]; p = 0.044) before VAP were independently associated with VAP development. After propensity score matching, VAP was associated with Open Access