How valid is the ICD-9-CM based AHRQ patient safety indicator for postoperative venous thromboembolism?
BACKGROUND
Hospital administrative data are being used to identify patients with postoperative venous thromboembolism (VTE), either pulmonary embolism (PE) or deep-vein thrombosis (DVT). However, few studies have evaluated the accuracy of these ICD-9-CM codes across multiple hospitals.


METHODS
The Agency for Healthcare Research and Quality (AHRQ) Patient Safety Indicator (PSI)-12 was used to identify cases with postoperative VTE in 80 hospitals that volunteered for either an AHRQ or University HealthSystem Consortium (UHC) validation project. Trained abstractors using a standardized tool and guidelines retrospectively verified all coded VTE events.


RESULTS
In the combined samples, the positive predictive value of the set of prespecified VTE codes for any acute VTE at any time during the hospitalization was 451 of 573 = 79% (95% CI: 75%-82%). However, the positive predictive value for acute lower extremity DVT or PE diagnosed after an operation was 209 of 452 = 44% (95% CI: 37%-51%) in the UHC sample and 58 of 121 = 48% (95% CI: 42-67%) in the AHRQ sample. Fourteen percent of all cases had an acute upper extremity DVT, 6% had superficial vein thrombosis and 21% had no acute VTE, however, 61% of the latter had a documented prior/chronic VTE. In the UHC cohort, the sensitivity for any acute VTE was 95.5% (95% CI: 86.4%-100%); the specificity was 99.5% (95% CI: 99.4%-99.7%).


CONCLUSIONS
Current PSI 12 criteria do not accurately identify patients with acute postoperative lower extremity DVT or PE. Modification of the ICD-9-CM codes and implementation of "present on admission" flags should improve the predictive value for clinically important VTE events.
Division of General Medicine, University of California, Davis, CA 95817, USA. rhwhite@ucdavis.edu
Richard H
RH
White
Banafsheh
B
Sadeghi
Daniel J
DJ
Tancredi
Patricia
P
Zrelak
Joanne
J
Cuny
Pradeep
P
Sama
Garth H
GH
Utter
Jeffrey J
JJ
Geppert
Patrick S
PS
Romano
D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D038801:International Classification of Diseases / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D019984:Quality Indicators, Health Care / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012737:Sex Factors; D014481:United States; D016270:United States Agency for Healthcare Research and Quality / Q000706:statistics & numerical data*; D054556:Venous Thromboembolism / Q000453:epidemiology*