Outcomes and prognostic factors for severe community-acquired pneumonia that requires mechanical ventilation

Background: Community-acquired pneumonia (CAP) remains a common and serious condition worldwide. The mortality from severe CAP remains high, and this has reached 50% in some series. This study was conducted to determine the mortality and predictors that contribute to in-hospital mortality for patients who exhibit CAP and acute respiratory failure that requires mechanical ventilation. Methods: We retrospectively reviewed the medical records of 85 patients with severe CAP as a primary cause of acute respiratory failure, and this required mechanical ventilation in a setting of the medical intensive care unit (ICU) of a tertiary university hospital between 2000 and 2003. Results: The overall in-hospital mortality was 56% (48/85). A Cox-proportional hazard model revealed that the independent predictive factors of in-hospital mortality included a PaCO₂ of less than 45 mmHg (p<0.001, relative risk [RR]: 4.73; 95% confidence interval [CI]: 2.16-10.33), a first 24-hour urine output of less than 1.5 L (p=0.006, RR: 2.46, 95% CI: 1.29-4.66) and a high APACHE II score (p=0.004, RR: 1.09, 95% CI: 1.03-1.16). Conclusions: Acute respiratory failure caused by severe CAP and that necessitates mechanical ventilation is associated with a high mortality rate. Initial hypercapnia and a large urine output favored survival, whereas a high APACHE II score predicted mortality.