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The validity of using ICD-9 codes and pharmacy records to identify patients with chronic obstructive pulmonary disease

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Microsoft Word 1472-6963-11-37-s2.doc (34KB) Simulated positive predictive values (PPV) and negative predictive values (NPV) for Model 88, by prevalence of COPD Microsoft Word
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Title: The validity of using ICD-9 codes and pharmacy records to identify patients with chronic obstructive pulmonary disease
Author(s): Cooke, Colin R.; Joo, Min J.; Anderson, Stephen M.; Lee, Todd A.; Udris, Edmunds M.; Johnson, Eric; Au, David H.
Subject(s): pulmonary pharmacy
Abstract: Background: Administrative data is often used to identify patients with chronic obstructive pulmonary disease (COPD), yet the validity of this approach is unclear. We sought to develop a predictive model utilizing administrative data to accurately identify patients with COPD. Methods: Sequential logistic regression models were constructed using 9573 patients with postbronchodilator spirometry at two Veterans Affairs medical centers (2003-2007). COPD was defined as: 1) FEV1/FVC < 0.70, and 2) FEV1/FVC < lower limits of normal. Model inputs included age, outpatient or inpatient COPD-related ICD-9 codes, and the number of metered does inhalers (MDI) prescribed over the one year prior to and one year post spirometry. Model performance was assessed using standard criteria. Results: 4564 of 9573 patients (47.7%) had an FEV1/FVC < 0.70. The presence of >= 1 outpatient COPD visit had a sensitivity of 76% and specificity of 67%; the AUC was 0.75 (95% CI 0.74-0.76). Adding the use of albuterol MDI increased the AUC of this model to 0.76 (95% CI 0.75-0.77) while the addition of ipratropium bromide MDI increased the AUC to 0.77 (95% CI 0.76-0.78). The best performing model included: >= 6 albuterol MDI, >= 3 ipratropium MDI, >= 1 outpatient ICD-9 code, >= 1 inpatient ICD-9 code, and age, achieving an AUC of 0.79 (95% CI 0.78-0.80). Conclusion: Commonly used definitions of COPD in observational studies misclassify the majority of patients as having COPD. Using multiple diagnostic codes in combination with pharmacy data improves the ability to accurately identify patients with COPD.
Issue Date: 2011-02-16
Publisher: BioMed Central
Citation Info: Cooke, C. R., Joo, M. J., Anderson, S. M., Lee, T. A., Udris, E. M., Johnson, E., & Au, D. H. 2011. The validity of using ICD-9 codes and pharmacy records to identify patients with chronic obstructive pulmonary disease. Bmc Health Services Research, 11. DOI: 10.1186/1472-6963-11-37
Type: Article
Description: The original source for this publication is at BioMed Central; DOI: 10.1186/1472-6963-11-37. © 2011 Cooke et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ISSN: 1472-6963
Sponsor: This study was supported by the Department of Veterans Affairs, Health Services Research and Development (DHA), American Lung Association (CI-51755-N) awarded to DHA, the American Thoracic Society Fellow Career Development Award (CRC), and the Robert Wood Johnson Foundation Clinical Scholar's Program (CRC). The funding bodies had no role in study design analysis, interpretation and writing of the manuscript, and in the decision to submit the manuscript for publication. The authors would also like to acknowledge the referees for their thoughtful contributions to the manuscript.
Date Available in INDIGO: 2011-05-25

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