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External Validation of ASPECT (Algorithm for Suspected Pulmonary Embolism Confirmation and Treatment)

Klil-Drori, Adi J. MD, MSc*,†; Prajapati, Dwip MD; Liang, Zhiying MSc§; Wang, Meng MSc§; Toupin, Dominique MD; Alothman, Latifah MD; Lang, Eddy MD; Suryanarayan, Deepa MD MSc; Tagalakis, Vicky MD, MSc*,∥

doi: 10.1097/MLR.0000000000001055
Online Article: Applied Methods

Background: Administrative health care databases are increasingly being used to study pulmonary embolism (PE), but the validity of single PE codes is variable. Using data from Quebec, Canada, we developed ASPECT (Algorithm for Suspected Pulmonary Embolism Confirmation and Treatment), combining 3 components to ascertain confirmed PE: emergency department (ED) diagnoses, imaging codes, and dispensed prescriptions or hospital diagnoses. Herein, we used unrelated administrative health care databases to externally validate ASPECT.

Methods: We used ED electronic health records (ED-EHRs) to identify all residents of Calgary (Alberta, Canada) with PE codes between January and June, 2016. We applied ASPECT by identifying imaging studies in the ED-EHR, admission diagnoses in linked discharge abstract database and filled prescriptions in linked pharmacy information. Confirmed PE in ASPECT was validated against chart review in the ED-EHR.

Results: The cohort included 498 patients. Overall, 258 (51.9%) were managed as outpatients and 327 were adjudicated to have confirmed PE; the positive predictive value (PV) of single PE codes was 65.6%. With ASPECT the positive PV was 96.5% [95% confidence interval (CI), 94.4–98.5%] and positive likelihood ratio was 10.9 (95% CI, 6.8–15.1). The negative PV and negative likelihood ratio were 85.1% (95% CI, 80.0–90.2%) and 0.1 (95% CI, 0.0–0.1), respectively. Overall agreement of ASPECT with confirmed PE was 92.2%. Further, ASPECT was similarly robust in inpatients and outpatients and was more precise than any 2-component combination of ASPECT.

Conclusions: Our findings reiterate the limitations of using single administrative codes for PE and suggest ASPECT as an acceptable tool to study PE.

*Center for Clinical Epidemiology, Jewish General Hospital

Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC

Departments of Hematology and Hematologic Malignancies

§Clinical Neurosciences, University of Calgary, Calgary, AB

Department of Medicine, McGill University, Montreal, QC

Department of Emergency Medicine, University of Calgary, Calgary, AB, Canada

This study was funded by CanVECTOR (Canadian venous thromboembolism clinical trials and outcomes) Network; the Network receives grant funding from the Canadian Institutes of Health Research (Funding Reference: CDT-142654).

A.J.K.-D. received speaking fees from Bristol-Myers-Squibb. V.T. received an investigator-initiated research grant from Sanofi. The remaining authors declare no conflict of interest.

Reprints: Vicky Tagalakis, MD, MSc, McGill University, Division of Internal Medicine, and Center for Clinical Epidemiology of the Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Sainte-Catherine, B-304, Montréal, QC, Canada H3T 1E2. E-mail:

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