Multicenter study comparing case definitions used to identify patients with chronic obstructive pulmonary disease.

Area of Science:

• Pulmonary Medicine
• Clinical Epidemiology
• Respiratory Research

Background:

• Clinical trials for chronic obstructive pulmonary disease (COPD) typically require airflow obstruction and clinical risk factors.
• International Classification of Diseases, Ninth Revision (ICD-9) codes and patient-reported physician diagnoses are commonly used in COPD studies.

Purpose of the Study:

• To evaluate the agreement between different case definitions for COPD.
• To assess the comparability of COPD patient populations identified using various definitions versus a clinical trial reference standard.

Main Methods:

• A cross-sectional study analyzed data from 1,206 participants in the COPD Outcomes-based Network for Clinical Effectiveness and Research Translation registry.
• Demographics, clinical data, and post-bronchodilator spirometry were collected.
• Agreement between case definitions was assessed using the kappa statistic (κ), and multivariable logistic regression identified factors associated with meeting the trial standard.

Main Results:

• Of 1,206 participants, 998 met at least one COPD case definition (91% via ICD-9, 73% via patient report, 56% via trial standard).
• Agreement between definitions was poor (κ = 0.20-0.26).
• Lack of airflow obstruction was the primary reason (89%) patients didn't meet the trial standard. Black, obese, and depressed patients were less likely to meet the trial standard.

Conclusions:

• Poor agreement exists between common COPD case definitions and the clinical trial reference standard.
• Findings raise concerns about applying clinical trial results to patients defined by other criteria.