Prognostic factors in severe community-acquired pneumonia in patients without co-morbid illness

Objectives: We wished to determine the prognostic factors and the impact of initial empirical antibiotic therapy on the outcome of severe community-acquired pneumonia in patients without underlying co-morbid illness. Methodology: This is a retrospective record review of consecutive patients with severe community-acquired pneumonia who were divided into those with and without underlying co-morbid illness. Results: There were 182 patients including 112 primary (no co-morbid illness) and 70 secondary (underlying co-morbid illness) pneumonias. The overall mortality was 41.8% and there were no differences in APACHE II score or mortality when comparing cases with primary (37.5%) and secondary infections (48.6%). The mortality was significantly higher in patients with negative microbiology. Univariate analysis identified a number of parameters and various antibiotic regimens, which appeared to be associated with a significantly poorer outcome. On multivariate analysis multilobar pulmonary consolidation, need for mechanical ventilation, inotropes and dialysis were documented to be independent predictors of mortality. Only in their absence could different antibiotic regimens be shown to have an apparent impact on outcome and further analysis suggested that the reason for these differences related predominantly to differences in the severity of the infection. Conclusions: Markers of disease severity appear to be the most important predictors of outcome in patients with severe community-acquired pneumonia.