Is healthcare-associated pneumonia a distinct entity needing specific therapy?

PURPOSE OF REVIEW

Healthcare-associated pneumonia (HCAP) was introduced in 2005 by American Thoracic Society/Infectious Diseases Society of America guidelines as a new entity of pneumonia, resembling nosocomial pneumonia rather than community-acquired pneumonia (CAP) in terms of frequency of multidrug-resistant (MDR) pathogens and outcomes, thus requiring broad spectrum initial antimicrobial coverage in order to prevent inadequate treatment and, as a consequence, excess mortality. This concept continues to be a subject of controversy. Main concerns relate to the definition of HCAP, the true frequency of MDR pathogens, and the impact of MDR pathogens on outcomes.

RECENT FINDINGS

Definitions of HCAP and the relative frequencies of HCAP defining subgroups were highly variable. All studies demonstrated an increased severity of pneumonia at presentation and an excess mortality from HCAP as compared to CAP. The incidence of MDR pathogens in different observational studies was slightly increased but generally low in most studies originating from Europe, South Korea, Canada, and Japan. However, the data do not support a causal relationship of MDR incidence and excess mortality. Instead, after adjustment for confounders, mortality might be related to hidden or documented treatment restrictions in elderly and severely disabled patients. Accordingly, HCAP guideline concordant antimicrobial treatment did not improve outcomes.

SUMMARY

The HCAP concept is based on varying definitions poorly predictive of MDR pathogens. The incidence of MDR pathogens is far lower than supposed in the original guideline document, and MDR pathogens do not seem to be the main cause of excess mortality. Broad antimicrobial coverage does not alter outcomes. As the HCAP concept results in a tremendous overtreatment without any evidence for improved outcomes, it should not be implemented in clinical practice prior to clear evidence that it is superior to a careful assessment of individual risk factors for MDR pathogens.