Severe community-acquired pneumonia: Characteristics and prognostic factors in ventilated and non-ventilated patients

Abstract

Background : Severe community-acquired pneumonia (SCAP) is associated with significant morbidity and mortality. Patients with SCAP and life-threatening acute respiratory failure may require invasive mechanical ventilation (IMV); however, there is limited information on these patients. Methods : We prospectively studied consecutive patients with SCAP. We assessed the characteristics and outcomes of patients on IMV, compared with those who needed non-invasive ventilation (NIV) and no ventilatory support, and determined predictors for mortality and evolution of mortality over time in this population. Results : Among 3,719 patients diagnosed of CAP during 12 years, 664 (18%) had criteria for SCAP; 154 (23%) were allocated to the IMV group, 94 (14%) to the NIV group, and 416 (63%) did not require any ventilatory support; 198 (30%) presented septic shock. In 370 (56%) cases the diagnosis of SCAP was based solely on the presence of 3 or more IDSA/ATS minor criteria. Streptococcus pneumoniae was the main pathogen in all groups. The 30-day mortality was higher in the IMV, compared to the NIV and non-ventilated groups (51, 33%, vs. 17, 18% and 77, 19%, respectively, p=0·001). IMV, but neither NIV nor shock, independently predicted 30-day mortality in multivariate analysis (adjusted odds-ratio 2.18, 95% confidence interval 1·12-4·24, p=0·022). The 30-day mortality did not significantly change over time during the study period. Conclusion: The need for IMV independently predicted 30-day mortality in patients with SCAP. Patients needing IMV should be a target population for future clinical trials on new interventions addressed to improve mortality of SCAP.