Impact of empirical treatment recommendations of European guidelines for nosocomial pneumonia. A prospective cohort study

<bold>Background:</bold> Nosocomial pneumonia (NP) is a major challenge in intensive care unit (ICU) and the latest European guidelines have proposed a new algorithm for empirical antimicrobial treatment. <bold>Aim:</bold> To assess the impact on outcomes of this tool within a population with high risk of multi-resistance and mortality. <bold>Methods:</bold> Retrospective analysis of a prospective cohort of 507 patients from 6 ICUs. Primary outcome was 28-day mortality. Secondary outcomes were 90-day mortality, ICU mortality, inadequate treatment, treatment failure and overtreatment. <bold>Results:</bold> 316 patients with microbiologically confirmed NP were included. There was no difference in terms of outcomes except for overtreatment, higher in the group treated according to guidelines (p<0.001). However, multivariate analysis found a significant effect modification by guidance adherence and septic shock at the diagnosis (p=0.027), suggesting a different efficacy in the two groups. In the first one ICU mortality (p=0.031) and adjusted 28-day mortality (p=0.034) were lower when the recommendations were implemented, while no difference was found in the other group (Figure). <bold>Conclusions:</bold> The algorithm proposed by the guidelines was able to reduce mortality in ICU and at 28 days in NP patients without septic shock, however, this superiority was not confirmed in the patients with septic shock.