American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Nov 2014
Multicenter Study Comparative StudyMulti-center Study Comparing Case Definitions Used to Identify Patients with Chronic Obstructive Pulmonary Disease.
Clinical trials in chronic obstructive pulmonary disease (COPD) usually require evidence of airflow obstruction and clinical risk factors. International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes or patient-reported physician diagnoses are often used for epidemiologic studies and performance improvement programs. ⋯ Findings highlight concerns about the applicability of findings in clinical trials to patients meeting other case definitions for COPD.