TTalbot VAE VAP IDWeek 2014 FINAL

VAP to VAE: Exploring the Epidemiology
of a New Surveillance Definition
Eileen M. Duggan MD,1 Vicki Brinsko RN,4 Barbara Martin RN MBA,5 and Thomas R. Talbot, MD, MPH2,3
From the Departments of Surgical Sciences,1 Medicine,2 and Health Policy,3 Vanderbilt University School of Medicine;
and the Department of Infection Prevention4 and Quality Safety and Risk Prevention,5
Vanderbilt University Medical Center, Nashville TN
Methods
Abstract
Background: Due to concerns about the subjectivity and inter-rater reliability of
the surveillance definition for VAP (ventilator-associated pneumonia), a more
objective outcome measure, VAE (ventilator-associated event), was released in
2013. We examined the epidemiology of the traditional VAP and new VAE
measures in 6 adult intensive care units (ICUs) and hypothesized that VAE rates
would be considerably higher than the traditional VAP rates and that correlation
between VAEs and traditional VAPs would be low.
Methods: Traditional VAP events (TradVAP) and VAEs in six adult ICUs (medical,
surgical, burn, trauma, cardiovascular, and neurosciences) at an academic
medical center were determined by trained personnel for the study period from
July to December 2012. VAEs were classified as a ventilator-associated condition
(VAC), infection-related VAC (IVAC), and possible/probable VAP (PossVAP) based on
NHSN definitions. Descriptive analyses were conducted to assess the proportion
of TradVAPs that were also identified as VAEs; TradVAP and VAE rates were also
compared.
Results: During the study period, 15 TradVAPs and 91 VAEs were identified in all
ICUs combined. Only 8/15 (53%) TradVAPs met the VAE definition, but of these,
75% (6/8) were identified as a PossVAP; the other two TradVAPs met criteria for
an IVAC only. The VAE rate was higher than the TradVAP rate across all units, but
units differed in the degree of rate increase (Table).
Conclusions: The overall VAE rate was 6-times higher than the TradVAP rate with
wide variation in the degree of increase across ICU types. Only half of the
identified TradVAPs were captured as a VAE event, but the majority of these VAEs
were classified as a possible VAP. Further research is needed to determine causes
of the VAEs in these units and the preventability of these.
Introduction
The CDC first included surveillance for nosocomial pneumonia as part of the National
Nosocomial Infection Surveillance System (NNIS) program. Over several years, the CDC
pneumonia (PNEU) definitions were refined and eventually included radiographic,
clinical and laboratory data. Patients on ventilators at the onset of PNEU or within 48
hours of the event were also classified as having a ventilator-associated pneumonia
(VAP). As more hospitals incorporated this outcome into healthcare-associated
infection (HAI) surveillance and as interest in the use of HAI performance data as a
means for hospital quality comparisons, a need for more specific definitions for
nosocomial pneumonia was identified. In particular, the subjectivity of the VAP
definition and the need for increased clinical credibility raised the scrutiny of the VAP
definition. In 2011, a new National Healthcare Safety Network (NHSN) surveillance
algorithm, referred to as ventilator-associated events (VAE), was developed. This
objective, tiered definition algorithm identifies VACs (ventilator-associated
conditions), IVACs (infection-related VACs) and possible and probable VAPs. With the
implementation of the new VAE definition at our institution, we compared VAE
events and rates with traditionally-defined VAP events and rates during a concurrent
period of time in six adult intensive care units at an academic medical center.
Setting: 6 adult ICUs at a large academic medical center
(includes burn, cardiovascular, medical, neurosurgical,
surgical, and trauma ICU types)
Results
Table. Traditional VAP and VAE events and event rates by unit
Event Rate
ICU Type
Bronchoscopy
Culture Rate
per 1000
Patient Days
(Mean
Monthly)
Burn
3.6
1
6
3
2
1
3.1
18.6
6x
Cardiovascular
13.0
1
19
6
11
2
0.8
15.6
19.5x
Medical
5.0
0
8
3
4
1
0.0
7.0
N/A
Neurosciences
3.8
1
14
6
6
2
1.3
17.4
13.4x
Surgical
15.5
6
20
10
8
2
5.3
17.6
3.3x
Trauma
29.7
6
24
9
3
12
4.2
16.6
4x
15
91
37
34
20
2.5
15.0
6x
Study Period: July through December 2012
Outcomes:
1) Traditional VAP: Ventilator-associated pneumonia events
as defined using the now-retired CDC definition in place
during 2012 (“TradVAP”)
2) Ventilator-Associated Events (VAE): Defined using 2013
CDC NHSN definitions (Figure 1). VAE were classified into
several different subtypes:

Ventilator-Associated Condition (VAC)

Infection-related Ventilator-Associated Condition
(IVAC)

Possible or Probable VAP – these events were
combined into a single outcome group for comparison
Analysis: Event rates per 1,000 ventilator days and
descriptive assessment of concordance of TradVAP
surveillance with VAE surveillance. An examination of the rate
of use of bronchoscopy-derived specimens used for
microbiologic culture per 1000 patient days was also assessed.
Figure 1. National Healthcare Safety Network Definition
Algorithm for Ventilator-Associated Events (2013 version)
Total
TradVAP
VAE rate
rate per
per 1000
1000 Vent
Vent Days
Days
Figure 2. Distribution of Traditional VAP and VAE
events, Adult ICUs July-December 2012
Fold
Increase,
TradVAP to
VAE Rate
 Only 8/15 (53%) TradVAPs met the
VAE definition (Figure 2)
 Of these, 75% (6/8) were identified
as a PossVAP; the other two
TradVAPs met criteria for an IVAC
only
 The VAE rate was higher than the
TradVAP rate across all units, but
units differed in the degree of rate
increase
 The difference between TradVAP
and VAE rates was smaller for the
two units where diagnostic
bronchoscopy was used extensively
in patients with respiratory
failure/potential pneumonia
(trauma and surgical) vs. the two
of the three ICUs that rarely used
bronchoscopy to diagnosis
underlying pulmonary illness
(medical and neurosciences)
Conclusions
The number and rate of VAE events were several-fold higher compared to surveillance
using the traditional VAP definition. These differences varied by ICU type, and may
reflect differences in diagnostic testing as well as underlying patient populations (e.g.
higher rates of non-infectious VAE events related to heart failure in the cardiovascular
ICU). Further research is needed to determine causes of the VAEs in these units and the
preventability of these important events.
Contact Information:
Thomas R. Talbot, MD MPH
A-2209 Medical Center North
1161 21st Ave. S.
Nashville, TN 37232
Phone: (615) 343-2035
email: [email protected]

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