Elsevier

American Heart Journal

Volume 144, Issue 2, August 2002, Pages 290-296
American Heart Journal

Clinical Investigations: Outcomes, Health Policy, and Managed Care
A multicenter study of the coding accuracy of hospital discharge administrative data for patients admitted to cardiac care units in Ontario,☆☆,,★★

https://doi.org/10.1067/mhj.2002.123839Get rights and content

Abstract

Background Cardiac health services researchers frequently use cohorts derived from administrative hospital discharge abstract data to study the outcomes and treatment of coronary artery disease. However, relatively limited data exist on the accuracy of the coding of cardiac diagnoses in discharge abstract data. The goal of this study was to examine the accuracy of the coding of acute myocardial infarction and other cardiac diagnoses in the Canadian Institute of Health Information hospital discharge abstracts. Methods Patients admitted to 58 cardiac care units (CCUs) in Ontario that participated in the Fastrak II Acute Coronary Syndromes registry were linked to CIHI hospital discharge abstracts. The most responsible diagnosis at hospital discharge in the administrative data was compared with the CCU discharge diagnosis in the clinical registry. Results A total of 58,816 CCU patients were linked to hospital discharge abstract data. The specificity, sensitivity, and positive predictive value of a most responsible diagnosis of acute myocardial infarction were 92.8%, 88.8%, and 88.5%, respectively. The specificity of CIHI diagnosis codes for arrhythmia, congestive heart failure, unstable angina, and chest pain not yet diagnosed were all at least 93.9%. However, the sensitivity of these CIHI diagnosis codes was no greater than 60.7%. Furthermore, the positive predictive values were no larger than 80.8%. Conclusion Myocardial infarction is generally accurately coded in Ontario hospital discharge abstract data. However, other cardiac diagnoses are less reliably coded in discharge abstract data. (Am Heart J 2002;144:290-6.)

Section snippets

Data sources

Data on each patient's diagnosis were obtained from 2 sources: the Fastrak II acute coronary syndromes registry and the CIHI hospital discharge abstracts database. The Fastrak II acute coronary syndromes database is a prospective clinical registry at a number of hospitals across Canada, including 58 hospitals from Ontario. In the CCU phase of the registry, data are gathered from consecutive patients admitted to the CCU in participating hospitals by the nurse looking after the patient in the CCU

Results

There were 61,688 eligible Fastrak II records for patients admitted between January 1, 1996, and March 1, 2000. Of these, 59,116 (95.8%) were linked to a CIHI discharge abstract. The Fastrak II discharge diagnosis was absent for 300 of these records (0.5%), resulting in a final cohort of 58,816 patients. Of the 59,116 patients who were linked to the CIHI database, 87.9% had an exact match on patient date of birth, sex, date of admission, and admitting institution. A further 6.6% of patients had

Discussion

Hospital discharge abstract databases are increasingly being used in health services research. However, it is important that the coding of cardiac diagnoses in these databases be validated. Our study represents one of the largest validation studies of the administrative databases ever undertaken. We linked prospective clinical registry data on 58,816 patients admitted to 58 CCUs in Ontario to hospital discharge abstract data. We examined the accuracy of the coding of AMI, arrhythmia, congestive

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Supported in part by an operating grant from the Canadian Institutes of Health Research (CIHR), and in part by a Canada Research Chair in Health Services Research, in part by the Ontario Ministry of Health and Long Term Care, and in part by Hoffmann-La Roche, Canada.

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The results and conclusions are those of the authors and should not be attributed to any of the sponsoring organizations.

Reprint requests: Peter Austin, PhD, Institute for Clinical Evaluative Sciences, G-160, 2075 Bayview Ave, Toronto, Ontario, M4N 3M5 Canada.

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E-mail: [email protected]

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