The incidence and longitudinal trends of patients with ST-elevation myocardial infarction (STEMI) presenting to United States (US) emergency departments (EDs) are currently unknown. Efforts to use effective treatments for cardiovascular disease may decrease ED STEMI presentation. We conducted a descriptive epidemiological analysis of STEMI visits to EDs from 2006 to 2011 using the Nationwide ED Sample, the largest source of US ED data, to determine the incidence of patients with STEMIs presenting to the US EDs. We included adult ED visits with an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of STEMI and calculated incidence rates for STEMI ED visits using US census population data. Incidence calculations were stratified by age group, geographic region, and year. From 2006 to 2011, there was a mean of 258,106 STEMIs presenting to EDs per year, decreasing from 300,466 in 2006 to 227,343 in 2011. Incidence of ED STEMI visits per 10,000 adults decreased from 10.1 (95% confidence interval [CI] 9.8 to 10.8) in 2006 to 7.3 (95% CI 6.8 to 7.8) in 2011. The Midwest had the highest rate of ED STEMIs at 10.0 (95% CI 9.2 to 10.8) and the West had the lowest with 6.6 (95% CI 6.1 to 7.0). The incidence of STEMI decreased for all age groups during the study period. In conclusion, we report the first national estimates of STEMI presentation to US EDs, which demonstrate decreasing incidence across all age groups and all geographic regions from 2006 to 2011. A decreasing STEMI incidence may affect the quality and timeliness of STEMI care. Continued national STEMI surveillance is needed to guide healthcare resource allocation.
Presentation of a patient with ST-elevation myocardial infarction (STEMI) to an emergency department (ED) represents an acute medical emergency requiring immediate complex care coordination to achieve narrow timeliness guidelines for myocardial reperfusion. Although cardiovascular disease prevalence is expected to increase in the United States, a more recent study of nearly 50,000 patient hospitalizations found significant reductions in hospitalizations for STEMI from 1999. However, neither of these earlier studies describes ED utilization for STEMI, national trends, or regional differences within the US. If the incidence of STEMI across the US is truly decreasing, particularly in combination with recent systematic efforts to take patients with STEMI straight to cardiac catheterization for reperfusion (i.e., bypassing the ED), significant changes may affect the ED’s role in the acute management of patients with STEMI. Therefore, we sought to quantify the contemporary incidence of STEMI in US EDs through a national sample of ED visits.
Methods
We conducted a cross-sectional analysis of STEMI visits to EDs in the US from 2006 to 2011, using the largest source of ED data in the US, the Nationwide ED Sample (NEDS). NEDS, a publicly available database from the Healthcare Cost and Utilization Project, contains a 20% sample of all hospital-based ED visits annually in the US. NEDS tracks geographic, hospital, and patient characteristics including diagnosis codes for patient visits. NEDS was constructed using the Healthcare Cost and Utilization Project State ED Databases and State Inpatient Databases. In 2011, the most recent year with NEDS data available, 30 states and 951 hospitals contributed data for 29 million ED visits. NEDS contains weights to calculate national estimates using the sample of ED visits contained within the data set. Previous research evaluated the quality of hospital discharge data and found that NEDS’ estimates of ED use are comparable to other national data sets for ED data.
For the current analysis, we included all adult (age ≥18 years) ED visits with a diagnosis of STEMI ( International Classification of Diseases, Ninth Revision, Clinical Modification codes 410.01, 410.11, 410.21, 410.31, 410.41, 410.51, 410.61, 410.81, or 410.91) and calculated incidence rates for STEMI ED visits using US census data. Incidence calculations were stratified by year (2006, 2007, 2008, 2009, 2010, and 2011), age group (18 to 34, 35 to 44, 45 to 54, 55 to 64, 65 to 74, 75 to 84, and ≥85 years old), and geographic region (Northeast, South, Midwest, and West).
Results
From 2006 to 2011, there were an estimated 1,548,634 ED visits for STEMIs in the US, representing 0.26% of all ED visits. The annual incidence of STEMI ED visits during this entire 6-year period was 8.5 (95% confidence interval 8.1 to 8.8) per 10,000 adults. When considering incidence separately by year, incidence decreased from 2006 to 2011, with decreasing incidence each subsequent year throughout the study period and across all age groups ( Figure 1 ) and geographic regions ( Table 1 ). Patients ≥85 years old had the highest incidence of STEMI ED visits, but also experienced the greatest decrease in incidence during the study period. Among the 4 geographic regions in the US, the West had the lowest overall rate of STEMI with 5.8 (95% confidence interval 5.0 to 6.5) STEMI ED visits per 10,000 adults and the Midwest had the largest reduction in STEMI incidence during the study period.
| Visits (95% CI) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | |||||||
| U.S. STEMI ED visits (n) | ||||||||||||
| 300,466 | 276,779 | 263,475 | 243,471 | 237,100 | 227,343 | |||||||
| Incidence of STEMI ED visits in U.S. (visits/10,000 adults/year) | ||||||||||||
| 10.1 | (9.3, 10.8) | 9.2 | (8.5, 9.9) | 8.7 | (8.0, 9.3) | 7.9 | (7.3, 8.6) | 7.7 | (7.1, 8.3) | 7.3 | (6.8, 7.8) | |
| Incidence of STEMI ED visits by Age Group (visits/10,000 adults/year) | ||||||||||||
| 18-34 | 0.5 | (0.4, 0.5) | 0.5 | (0.4, 0.6) | 0.5 | (0.4, 0.5) | 0.4 | (0.3, 0.4) | 0.5 | (0.4, 0.5) | 0.4 | (0.4, 0.4) |
| 35-44 | 4.1 | (3.7, 4.5) | 3.9 | (3.5, 4.2) | 3.8 | (3.5, 4.2) | 3.3 | (3.0, 3.6) | 3.4 | (3.0, 3.7) | 3.3 | (3.0, 3.6) |
| 45-54 | 11.7 | (10.7, 12.6) | 10.9 | (10.0, 11.8) | 10.3 | (9.4, 11.2) | 9.7 | (8.9, 10.5) | 9.4 | (8.6, 10.2) | 9.0 | (8.3, 9.8) |
| 55-64 | 20.8 | (19.1, 22.5) | 18.5 | (17.0, 20.1) | 17.7 | (16.2, 19.1) | 16.3 | (14.9, 17.6) | 15.6 | (14.3, 16.8) | 14.7 | (13.6, 15.8) |
| 65-74 | 31.3 | (28.8, 33.8) | 27.7 | (25.5, 30.0) | 25.6 | (23.6, 27.7) | 23.6 | (21.8, 25.5) | 21.8 | (20.1, 23.6) | 21.1 | (19.5, 22.7) |
| 75-84 | 47.2 | (43.6, 50.8) | 42.5 | (39.2, 45.9) | 38.4 | (35.3, 41.6) | 34.1 | (31.3, 36.8) | 32.0 | (29.5, 34.6) | 29.5 | (27.3, 31.6) |
| 85+ | 83.4 | (76.9, 90.0) | 73.5 | (67.6, 79.4) | 67.5 | (61.9, 73.1) | 58.8 | (53.7, 63.8) | 55.9 | (51.4, 60.5) | 49.5 | (45.8, 53.2) |
| Incidence of STEMI ED visits by U.S. Geographic Region (visits/10,000/year) | ||||||||||||
| Northeast | 8.8 | (7.1, 10.5) | 8.1 | (6.6, 9.6) | 7.8 | (6.2, 9.4) | 7.3 | (5.9, 8.8) | 7.1 | (5.8, 8.4) | 6.8 | (5.5, 8.0) |
| Midwest | 12.4 | (10.5, 14.3) | 11.0 | (9.4, 12.7) | 9.8 | (8.3, 11.3) | 9.2 | (7.8, 10.6) | 9.2 | (7.8, 10.7) | 8.4 | (7.2, 9.7) |
| South | 10.9 | (9.6, 12.3) | 10.0 | (8.7, 11.3) | 9.6 | (8.3, 10.8) | 8.5 | (7.4, 9.6) | 8.0 | (6.9, 9.1) | 7.9 | (7.0, 8.8) |
| West | 7.5 | (6.2, 8.7) | 6.9 | (5.7, 8.1) | 6.9 | (5.8, 7.9) | 6.3 | (5.2, 7.3) | 6.1 | (5.2, 7) | 5.8 | (5.0, 6.5) |
Results
From 2006 to 2011, there were an estimated 1,548,634 ED visits for STEMIs in the US, representing 0.26% of all ED visits. The annual incidence of STEMI ED visits during this entire 6-year period was 8.5 (95% confidence interval 8.1 to 8.8) per 10,000 adults. When considering incidence separately by year, incidence decreased from 2006 to 2011, with decreasing incidence each subsequent year throughout the study period and across all age groups ( Figure 1 ) and geographic regions ( Table 1 ). Patients ≥85 years old had the highest incidence of STEMI ED visits, but also experienced the greatest decrease in incidence during the study period. Among the 4 geographic regions in the US, the West had the lowest overall rate of STEMI with 5.8 (95% confidence interval 5.0 to 6.5) STEMI ED visits per 10,000 adults and the Midwest had the largest reduction in STEMI incidence during the study period.
