Descriptive Epidemiology and Outcomes of Nonventilated Hospital-Acquired, Ventilated Hospital-Acquired, and Ventilator-Associated Bacterial Pneumonia in the United States, 2012–2019
Authors: Zilberberg Marya D. , Nathanson Brian H. , Puzniak Laura A. , Shorr Andrew F. 
Published: September 2021

OBJECTIVES:
Multiple randomized controlled trials exploring the outcomes of patients with ventilator-associated bacterial pneumonia and hospital-acquired bacterial pneumonia have noted that hospital-acquired bacterial pneumonia patients who require subsequent ventilated hospital-acquired bacterial pneumonia suffered higher mortality than either those who did not (nonventilated hospital-acquired bacterial pneumonia) or had ventilator-associated bacterial pneumonia. We examined the epidemiology and outcomes of all three conditions in a large U.S. database.

DESIGN:
Retrospective cohort.

SETTING:
Two hundred fifty-three acute-care hospitals, United States, contributing data (including microbiology) to Premier database, 2012–2019.

PATIENTS:
Patients with hospital-acquired bacterial pneumonia or ventilator-associated bacterial pneumonia identified based on a slightly modified previously published International Classification of Diseases, 9th Edition/International Classification of Diseases, 10th Edition-Clinical Modification algorithm.

INTERVENTIONS:
None.

MEASUREMENTS AND MAIN RESULTS:
Among 17,819 patients who met enrollment criteria, 26.5% had nonventilated hospital-acquired bacterial pneumonia, 25.6% vHAPB, and 47.9% ventilator-associated bacterial pneumonia. Ventilator-associated bacterial pneumonia predominated in the Northeastern United States and in large urban teaching hospitals. Patients with nonventilated hospital-acquired bacterial pneumonia were oldest (mean 66.7 ± 15.1 yr) and most likely White (76.9%), whereas those with ventilator-associated bacterial pneumonia were youngest (59.7 ± 16.6 yr) and least likely White (70.3%). Ventilated hospital-acquired bacterial pneumonia was associated with the highest comorbidity burden (mean Charlson score 4.1 ± 2.8) and ventilator-associated bacterial pneumonia with the lowest (3.2 ± 2.5). Similarly, hospital mortality was highest among patients with ventilated hospital-acquired bacterial pneumonia (29.2%) and lowest in nonventilated hospital-acquired bacterial pneumonia (11.7%), with ventilator-associated bacterial pneumonia in-between (21.3%). Among survivors, 24.5% of nonventilated hospital-acquired bacterial pneumonia required a rehospitalization within 30 days of discharge, compared with 22.5% among ventilated hospital-acquired bacterial pneumonia and 18.8% ventilator-associated bacterial pneumonia. Unadjusted hospital length of stay after infection onset was longest among ventilator-associated bacterial pneumonia and shortest among nonventilated hospital-acquired bacterial pneumonia patients. Median total hospital costs mirrored length of stay: ventilator-associated bacterial pneumonia $77,657, ventilated hospital-acquired bacterial pneumonia $62,464, and nonventilated hospital-acquired bacterial pneumonia $39,911.

CONCLUSIONS:
Both hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia remain associated with significant mortality and cost in the United States. Our analyses confirm that of all three conditions, ventilated hospital-acquired bacterial pneumonia carries the highest risk of death. In contrast, ventilator-associated bacterial pneumonia remains most costly. Nonventilated hospital-acquired bacterial pneumonia survivors were most likely to require a readmission within 30 days of discharge.