Admission route and use of invasive procedures during hospitalization for acute myocardial infarction: analysis of 2007-2011 National Health Insurance database

OBJECTIVES: The goal of this study was to investigate trends in admission to the emergency department and the use of invasive or surgical procedures during hospitalization for acute myocardial infarction (AMI) in Korea. METHODS: The National Health Insurance (NHI) claims database between 2007 and 2011 was used. We identified all admission claims that included codes from the tenth revision of the International Classification of Diseases beginning with I21 as the primary or secondary diagnosis. Information about the admission route, admission date, discharge date, and whether coronary artery angiography, angioplasty, or bypass surgery was performed was also obtained from the NHI database. RESULTS: Of the 513,886 relevant admission claims over the five years encompassed by this study, 295,001 discrete episodes of admission for AMI were identified by analyzing the date and length of each admission and the interval between admissions. The number of AMI admissions gradually decreased from 66,883 in 2007 to 47,656 in 2011. The number and proportion of admissions through the emergency department also decreased from 38,118 (57.0%) in 2007 to 24,001 (50.4%) in 2011. However, during the same period, admissions in which invasive or surgical procedures were performed increased from 15,342 (22.9%) to 17,505 (36.7%). CONCLUSIONS: The reported numbers of emergency department visits and admissions for AMI decreased from 2007 to 2011. However, only a small portion of the patients underwent invasive or surgical procedures during hospitalization, although the number of admissions involving invasive or surgical procedures has increased. These findings suggest that simply counting the number of admission claims cannot provide valid information on trends in AMI occurrence.