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Research Letter
Feb 27, 2012

Increasing US Rates of Endocarditis With Staphylococcus aureus: 1999-2008

Author Affiliations

Author Affiliations: Department of Health Policy and Management, University of North Carolina Gillings School of Global Public Health (Mr Federspiel and Dr Stearns), and Division of Infectious Diseases (Dr Peppercorn), University of North Carolina School of Medicine (Mr Federspiel), Chapel Hill; GlaxoSmithKline, Research Triangle Park, North Carolina (Dr Peppercorn); Division of Infectious Diseases and Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina (Drs Chu and Fowler).

Arch Intern Med. 2012;172(4):363-365. doi:10.1001/archinternmed.2011.1027

Estimates of the incidence and impact of bacterial infective endocarditis (IE) have been limited by the infrequency of the disease. Administrative data analyses can provide important information across a broad range of hospitals and regions. We used a recent nationally representative sample1 to estimate the incidence of hospitalizations for bacterial IE in the United States.

We conducted a retrospective cohort study using the 1999 through 2008 Nationwide Inpatient Sample (NIS), which is produced by the Agency for Healthcare Research and Quality.1 The NIS is the largest all-payer inpatient database in the United States (approximately 8 million records per year).1 Admissions related to bacterial IE were identified by the presence of International Classification of Diseases, Ninth Revision (ICD-9) codes 421.0, 421.1, 421.9, or 996.61, combining 2 previous strategies.2,3 The etiologic agent of IE was determined by the presence of organism-specific infection (eg, 041.x) and bacteremia codes (038.x). Incidence was estimated using the rate of IE-related discharges per 100 000 US population-years. Rates were calculated quarterly based on discharge date; the denominator was adjusted annually based on the US population.