The Prevalence of COPD in Individuals with Acute Coronary Syndrome: A Spirometry-Based Screening Study

Abstract

Background: The prevalence of COPD among individuals with acute coronary syndrome (ACS) is estimated at 5% to 18%, and COPD appears to be a predictor of poor outcome. Diagnosis of COPD has mostly been based on medical records without spirometry. As COPD is largely undiagnosed and misdiagnosed, the prevalence and clinical significance of COPD in the ACS population has not been reliably assessed. The present study aimed to estimate the prevalence of COPD in patients with ACS and evaluate the accuracy of medical record-based COPD diagnoses. Methods: This was a single-centre spirometry screening study for COPD in patients admitted for ACS in the county of Jämtland, Sweden. Patient medical records were reviewed to register previous medical history. Spirometry was performed prior to discharge or at the first follow-up outpatient visit after discharge. COPD was defined as a post-bronchodilator FEV1/FVC of <0.7 or below lower limit of normal. Results: Of 743 eligible patients, 407 performed spirometry. Five percent had COPD according to medical records; 11% and 5% fulfilled spirometric criteria of COPD according to FEV1/FVC of < 0.7 (p = 0.002) and below lower limit of normal definitions, respectively. “COPD according to medical history” had a sensitivity of 23%, specificity of 98%, positive predictive value of 53%, and negative predictive value of 91% compared with spirometric COPD FEV1/FVC of < 0.7 Conclusions: In patients with ACS, COPD is underdiagnosed and misdiagnosed. We raise concerns regarding the validity of medical record-based COPD in evaluating the biological and clinical association between COPD and coronary disease. ­Clinical Trial Registration: ISRCTN number 05697808 (www. controlled-trials.com)

Keywords :

• chronic obstructive pulmonary disease
• epidemiology
• diagnosis
• validity

Acknowledgments

We thank the research nurses at the Unit of Cardiology for their assistance with this project. This study was financially supported by the Research & Development Unit of the Jämtland County Council (Sweden), and The Swedish Heart and Lung Association. The sponsors had no influence on the study design, data collection, data analysis, interpretation of data, writing of the manuscript or in the decision to submit the manuscript for publication.

Declaration of Interest Statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Abbreviations
ACS, acute coronary syndrome	=
CI, confidence interval	=
COPD, chronic obstructive pulmonary disease	=
CVD, cardiovascular disease	=
FEV1, forced expiratory volume in one second	=
FVC, forced expiratory volume	=
GOLD, Global initiative for Obstructive Lung Disease	=