A Case-Control Study Assessing the Impact of Nonventilated Hospital-Acquired Pneumonia on Patient Outcomes

Abstract

Background: Nonventilated hospital-acquired pneumonia (NVHAP) is a serious nosocomial infection that is increasingly attributed to antibiotic-resistant bacteria.

Methods: This is a retrospective case-control study comparing patients with and those without NVHAP from January 1, 2014 to December 31, 2014 at Barnes-Jewish Hospital, a 1,300-bed urban academic medical center in St. Louis, Missouri.

Results: One hundred seventy-four consecutive patients with NVHAP were enrolled. A random sample of 696 control patients matched by age, sex, race, and hospital admission date were selected from a total of 5,322 potential matched control subjects. NVHAP was pathogen-negative in 98 cases (56.3%). Respiratory viruses were identified in 42 patients (24.1%), gram-negative bacteria were seen in 25 patients (14.4%), and gram-positive bacteria were identified in 20 patients (11.5%). Individuals in whom NVHAP developed were more likely to die (15.5% vs 1.6%; P < .01), to require intensive care (56.3% vs 22.8%; P < .01) or mechanical ventilation (19.0% vs 3.9%; P < 0.01), and to have a longer hospital length of stay (15.9 days [range, 9.8-26.3 days] vs 4.4 days [range, 2.9-7.3 days]; P < 0.01). This case-control study identified a strong association between hospital mortality and NVHAP, with patients who acquired NVHAP having an 8.4 times greater odds of death (95% CI, 5.6-12.5).

Conclusions: The occurrence of NVHAP was associated with significant increases in mortality, the use of intensive care and mechanical ventilation, and hospital length of stay. We also found that respiratory viruses were an important cause of NVHAP. These findings suggest that efforts aimed at the successful prevention of NVHAP could improve patient outcomes and reduce health-care costs.

Keywords: antibiotic resistance; outcomes; pneumonia.

Figure 1

Study flow diagram. Case and control patients were selected from the Barnes-Jewish Hospital Informatics Repository. ICD-9 = International Classification of Diseases, Ninth Revision.

Figure 2

Hospital mortality for patients with (cases) and without (control subjects) nonventilated hospital-acquired pneumonia stratified by Charlson comorbidity index.