Surveillance Definitions for Nonventilator Hospital-Acquired Pneumonia

The objective surveillance for nonventilator hospital-acquired pneumonia (HAP) via electronically computable definitions that incorporate common clinical criteria is feasible and generates incidence, mortality, and adjusted odds ratios [OR] for hospital mortality similar to those generated from manual surveillance, according to results from a cohort study in 2 tertiary care referral centers and 2 community hospitals in Massachusetts conducted between May 31, 2015 and July 1, 2018, published in JAMA Open Network.

All 310,651 non-ventilated patients aged ≥18 years admitted to these facilities were included in the study. For nonventilator HAP, 10 definitions were proposed using clinically meaningful combinations of 6 potential surveillance criteria. These criteria were: worsening oxygenation, fever (temperature >38°C), white blood cell count <4000/μL or >12 000/μL, performance of chest imaging, submission of respiratory specimen for culture, and 3 or more days of new antibiotics.

The 310,651 patients represented 489,519 admissions, including 205,054 patients with 311,484 admissions of ≥3 days. The incidence rate for candidate definitions per 100 admissions ranged from 3.4 events of worsening oxygenation alone to 0.9 events for worsening oxygenation and at least 3 days of new antibiotics to 0.6 events for worsening oxygenation, at least 3 days of new antibiotics, fever, abnormal white blood cell count, and performance of chest imaging. The range of crude mortality rates was 16.1% in patients with worsening oxygen alone compared with 27.7% in patients with worsening oxygenation, at least 3 days of antibiotics, fever or abnormal white blood cell count, and chest imaging.

Patients who met the candidate nonventilator HAP definitions stayed in hospital 2-times as long as their matched controls, adjusted ORs ranged from 1.8 (95% CI, 1.7-1.8) to 2.1 (95% CI, 2.0-2.1). They were also 4- to 6-times as likely to die in hospital: adjusted ORs ranged from 3.8 (95% CI, 3.5-4.0) to 6.5 (95% CI, 5.2-8.2). The agreement between the candidate definitions and clinical diagnosis was deemed fair (k= 0.33).

The conclusions of this study was limited due to it being conducted hospitals from a single region. While the findings were similar across hospitals and matched independent estimates, they may differ in other clinical settings with distinct populations and clinical practices. Also, estimates of potential excess time to discharge and mortality rate may be biased by residual confounding and only the association between surveillance definitions and clinically diagnosed pneumonia in patients with worsening oxygenation was assessed, which may have led to an overestimation of sensitivity. Finally, the proposed definitions are only amenable to implementation in hospital systems with comprehensive electronic health records that include vital signs, demographics, antibiotic administrations, radiographic procedures, clinical cultures, and laboratory values, along with analytic support to extract and analyze these data.

Investigators concluded that the candidate definitions yielded incidence and mortality rates comparable to existing estimates based on manual surveillance and were associated with longer time to discharge and higher mortality rates. Therefore, they believe these definitions may provide hospitals with, “an efficient and objective means to conduct routine surveillance for [nonventilator] HAP and thus to develop and evaluate prevention programs.”

Reference

Ji W, McKenna C, Ochoa A, et al. Development and assessment of objective surveillance definitions for nonventilator hospital-acquired pneumonia. JAMA Netw Open. 2019;2:e1913674.