Improved survival among ICU-hospitalized patients with community-acquired pneumonia by unidentified organisms: a multicenter case–control study

A retrospective analysis from prospectively collected data was conducted in intensive care units (ICUs) at 33 hospitals in Europe comparing the trend in ICU survival among adults with severe community-acquired pneumonia (CAP) due to unknown organisms from 2000 to 2015. The secondary objective was to establish whether changes in antibiotic policies were associated with different outcomes. ICU mortality decreased ( p = 0.02) from 26.9 % in the first study period (2000–2002) to 15.7 % in the second period (2008–2015). Demographic data and clinical severity at admission were comparable between groups, except for age over 65 years and incidence of cardiomyopathy. Over time, patients received higher rates of combination therapy (94.3 vs. 77.2 %; p