The Burden of Community-Acquired Pneumonia Requiring Admission to ICU in the United States

Background: A paucity of studies have assessed the epidemiology of community-acquired pneumonia (CAP) that require ICU admission. We conducted a study on this group of patients with the primary objective of defining the incidence, epidemiology, and mortality rate of CAP in the ICUs in Louisville, Kentucky. The secondary objective was to estimate the number of patients who were hospitalized and the number of deaths that were associated with CAP in ICU in the United States.

Research questions: What is epidemiology of CAP in the ICU in Louisville, Kentucky, and the projected incidence in the United States?

Study design and methods: This was a secondary analysis of a prospective population-based cohort study. The setting was all nine adult hospitals in Louisville, Kentucky. The annual incidence of CAP in the ICU per 100,000 adults was calculated for the whole adult population of Louisville. The number of patients who were hospitalized because of CAP in ICU in the United States was estimated by multiplying the Louisville incidence rate of CAP in ICU by the 2014 US adult population.

Results: From a total of 7,449 unique patients who were hospitalized with CAP, 1,707 patients (23%) were admitted to the ICU. The incidence of CAP in the ICU was 145 cases per 100,000 population of adults. Cases of CAP in the ICU were clustered in patients from areas of the city with high poverty. The mortality rate of patients with CAP in ICU was 27% at 30 days and 47% at one year. In the United States, the estimated number of patients who were hospitalized with CAP requiring the ICU was 356,326 per year, and the estimated number of deaths at 30 days and one year were 96,206 and 167,474, respectively.

Interpretation: Almost one in five patients who are hospitalized with CAP requires intensive care. Poverty is associated with CAP in the ICU. Nearly one-half of patients with CAP in the ICU will die within one year. Because of its significant burden, CAP in the ICU should be a high priority in research agenda and health policy.