Hospitalizations for Acute Exacerbations of Chronic Obstructive Pulmonary Disease: How You Count Matters

ABSTRACT

ICD-9-CM diagnosis codes are increasingly used to estimate the burden of disease, as well as to evaluate the quality of care and outcomes of various conditions. Acute exacerbations of COPD (AE-COPD) are common and associated with substantial health and financial burden in the U.S. Whether published algorithms that employ different combinations of ICD-9-CM codes to identify patients hospitalized for AE-COPD yield similar or different estimates of disease burden is unclear. In this study, the Nationwide Inpatient Sample from years 2000–2006 was used to identify and compare the number of hospitalizations, healthcare utilization, and outcomes for patients hospitalized for AE-COPD in the U.S. AE-COPD was identified using five different published ICD-9-CM algorithms. Estimates of the annual number of hospitalizations for AE-COPD in the U.S. varied more than 2-fold (e.g., 421,000 to 870,000 in 2006). Outcomes and healthcare utilization of patients hospitalized for AE-COPD varied substantially, depending on the algorithm used (e.g., in-hospital mortality 2.0% to 5.1%, total hospital days 2.0 to 5.1 million in 2006). Observed trends in the number of hospitalizations over the 7-year period varied depending on which algorithm was used. In conclusion, the estimated health burden and trends in hospitalizations for AE-COPD in the United States differ, depending on which ICD-9-CM algorithm is used. To improve our understanding of the burden of AE-COPD and to ensure that quality of care initiatives are not misdirected, a validated approach to identifying patients hospitalized for AE-COPD is needed.

ACKNOWLEDGMENTS

We would like to thank Dr. Fernando Holguin, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, for his input on a prior version of this manuscript. This work was supported by the National Institutes of Health [Grant HL07605, B. Stein] and AHRQ [Grant 5U18HS016967-02, J. Krishnan, G. Schumock, T. Lee].