title: 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.
authors.affiliation: Rush University Medical Center, Section of Pulmonary and Critical Care Medicine, Chicago, Illinois, USA. brian_stein@rush.edu
authors.forename: Brian D
authors.initials: BD
authors.lastname: Stein
authors.forename: Jeffery T
authors.initials: JT
authors.lastname: Charbeneau
authors.forename: Todd A
authors.initials: TA
authors.lastname: Lee
authors.forename: Glen T
authors.initials: GT
authors.lastname: Schumock
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lindenauer
authors.forename: Adriana
authors.initials: A
authors.lastname: Bautista
authors.forename: Diane S
authors.initials: DS
authors.lastname: Lauderdale
authors.forename: Edward T
authors.initials: ET
authors.lastname: Naureckas
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Krishnan
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006302:Health Services Research / Q000379:methods*; D017052:Hospital Mortality / Q000639:trends; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D015994:Incidence; D007902:Length of Stay / Q000639:trends; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000628:therapy*; D012008:Recurrence; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology