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Predictive Value of the Present-On-Admission Indicator for Hospital-acquired Venous Thromboembolism

Khanna, Raman R. MD, MAS*; Kim, Sharon B. MD*; Jenkins, Ian MD; El-Kareh, Robert MD, MPH; Afsarmanesh, Nasim MD, SFHM; Amin, Alpesh MD, MBA§; Sand, Heather MD; Auerbach, Andrew MD, MPH*; Chia, Catherine Y. MD; Maynard, Gregory MD, MSc; Romano, Patrick S. MD, MPH#; White, Richard H. MD, FACP#

doi: 10.1097/MLR.0b013e318286e34f
Applied Methods

Background: Hospital-acquired venous thromboembolic (HA-VTE) events are an important, preventable cause of morbidity and death, but accurately identifying HA-VTE events requires labor-intensive chart review. Administrative diagnosis codes and their associated “present-on-admission” (POA) indicator might allow automated identification of HA-VTE events, but only if VTE codes are accurately flagged “not present-on-admission” (POA=N). New codes were introduced in 2009 to improve accuracy.

Methods: We identified all medical patients with at least 1 VTE “other” discharge diagnosis code from 5 academic medical centers over a 24-month period. We then sampled, within each center, patients with VTE codes flagged POA=N or POA=U (insufficient documentation) and POA=Y or POA=W (timing clinically uncertain) and abstracted each chart to clarify VTE timing. All events that were not clearly POA were classified as HA-VTE. We then calculated predictive values of the POA=N/U flags for HA-VTE and the POA=Y/W flags for non-HA-VTE.

Results: Among 2070 cases with at least 1 “other” VTE code, we found 339 codes flagged POA=N/U and 1941 flagged POA=Y/W. Among 275 POA=N/U abstracted codes, 75.6% (95% CI, 70.1%–80.6%) were HA-VTE; among 291 POA=Y/W abstracted events, 73.5% (95% CI, 68.0%–78.5%) were non-HA-VTE. Extrapolating from this sample, we estimated that 59% of actual HA-VTE codes were incorrectly flagged POA=Y/W. POA indicator predictive values did not improve after new codes were introduced in 2009.

Conclusions: The predictive value of VTE events flagged POA=N/U for HA-VTE was 75%. However, sole reliance on this flag may substantially underestimate the incidence of HA-VTE.

*Department of Medicine, Division of Hospital Medicine, UCSF, San Francisco

Department of Medicine, Division of Hospital Medicine, UCSD, San Diego

Department of Medicine, UCLA, Los Angeles

§Division of General Internal Medicine, Department of Medicine

Department of Medicine, UCI, Irvine

Department of Medicine

#Division of General Internal Medicine, Department of Medicine, UCD, Davis, CA

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Supported by the UC Collaborative to Reduce Hospital Acquired Venous thromboembolism (HA-VTE): Stop the Clot (PI=G.M.) and partly through department funds at each UCMC.

The authors declare no conflict of interest.

Reprints: Raman R. Khanna, MD, MAS, Department of Medicine, Division of Hospital Medicine, UCSF, 533 Parnassus Ave, U136, San Francisco, CA 94143-0131. E-mail:

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