Assessment of Mortality Predictors in Patients with Severe Community-acquired Pneumonia Requiring ICU Admission

Abstract

Background: Community-acquired pneumonia (CAP) is a leading cause of death. The knowledge of pathogen patterns causing severe CAP is crucial. Study Objectives: The purpose of this prospective study was to describe patient characteristics, mortality rates, and etiological pathogens in patients with severe CAP who required ICU admission, as well as to identify predictors of mortality. Patients and Methods: This was a multicenter prospective observational study of 57 consecutive patients who were admitted to the ICU with diagnosis of severe CAP from October 2012 to August 2015. Results: In total, 57 individuals were included in the trial, with a 49.1% overall ICU death rate. The most common comorbidities associated with severe CAP were heart disease and chronic obstructive pulmonary disease. Comparison between survivors and non-survivors revealed that mortality was associated with old age (P=0.01), low diastolic blood pressure (P=0.04), low PaO2/FiO2 (P=0.04), high acute physiology and chronic health evaluation II (APACHE II) score (P=0.001), (CURB-65) score (P=0.005), low hemoglobin (P=0.008), and high urea (P=0.04). The univariate analysis revealed the following predictors of mortality: : age older than 65 years (P=0.03); APACHE II score greater than 20 (P=0.007); CURB-65 of 3 or greater (0.03); total leukocyte count less than 4 or greater than 11×109/(P=0.04); PaO2/FiO2 less than 250 (P=0.03); serum urea greater than 30 mg/dl (P=0.04); presence of septic shock (P=0.003); mechanical ventilation requirement (P=0.02); and bilateral or multilobar infiltrates on chest radiograph (P=0.03). Multiple regression analysis identified. High APACHE II score (>20) and septic shock as significant independent predictors of mortality in severe CAP. In 52.6 percent of cases, microbiological identification was obtained, with positive blood cultures in 17.5 percent. Streptococcus pneumoniae (S. pneumoniae) (19.3%) and Staphylococcus aureus (S. aureus) were the pathogens most often isolated (15.8 percent). Conclusion: The mortality rate in patients with severe CAP was high, as reported by the majority of other studies. Septic shock and a high APACHE II were both independent predictors of death. The most common comorbidities were cardiovascular disease and chronic obstructive pulmonary disease. Microbiological identification was obtained in 52.6 percent of cases, with S. pneumonia and S. aureus being the most frequently isolated pathogens.