Cardiology and vascular/original researchThe Internet Tracking Registry of Acute Coronary Syndromes (i*trACS): A Multicenter Registry of Patients With Suspicion of Acute Coronary Syndromes Reported Using the Standardized Reporting Guidelines for Emergency Department Chest Pain Studies
Introduction
More than 5.5 million patients present to a United States emergency department (ED) with chest pain and other symptoms related to acute coronary syndrome each year.1 Acute coronary syndrome is observed in people of all ages, races, and socioeconomic backgrounds. The clinical presentation of acute coronary syndrome is heterogeneous, varying from ST-segment elevation with positive cardiac biomarker results of myocardial necrosis to the very subtle cases of acute coronary syndrome with no observable ECG changes,2 negative cardiac biomarker results,3 atypical signs and symptoms,4 and a nonspecific medical history.4 This broad spectrum of disease has been extensively researched, yet appropriate evaluation and treatment can remain problematic for individual patients, and the impact of acute coronary syndrome remains enormous. Recently, improvements in medical management and invasive therapeutic options for these patients have resulted in the publication of numerous guidelines for appropriate evaluation and treatment of acute coronary syndrome.5, 6, 7 Despite these expert opinions, guidelines are poorly followed, disparities in outcomes persist, and emergency physicians miss up to 2% of acute myocardial infarctions in patients presenting to EDs.8, 9 To reduce the burden of acute coronary syndrome on patients and providers, delineating the relationship between evaluation, treatment, and outcomes is fundamental.
Randomized controlled trials can demonstrate the effectiveness of therapies or treatment pathways. They cannot help us to completely understand the complex presentations of acute coronary syndrome in the clinical setting. The only feasible method for unraveling the interaction between practice patterns, manners of presentation, patient characteristics, diagnostic testing, therapy, and outcomes in contemporary practice is through observational studies.
To our knowledge, the only inclusive multicenter observational data sets compiled heretofore are those reported by Goldman et al10 and Selker et al,11 which were used to develop risk-stratification protocols for ED chest pain patients. Although inclusive, both data sets commenced more than 15 years ago, when many of today’s guidelines, as well as diagnostic and therapeutic options, did not exist. This limits generalizability to today’s practice of emergency medicine. Further, only limited descriptions of these patient populations are available, providing insufficient information for evaluating generalizability. Guidelines for reporting studies of chest pain patients have recently been developed to assist researchers in satisfying the minimum description of the sample necessary for understanding ED chest pain studies.12 These guidelines offer data definitions and indicate those variables that must be reported to interpret study results in an optimal and generalizable fashion. No multicenter observational cohort study has previously attempted to use these guidelines to describe a large patient population with suspected acute coronary syndrome.
The dearth of more recent observational studies of well-described patient populations presenting to EDs with any suspicion of acute coronary syndrome represents a significant barrier to understanding the relationships between patients, signs and symptoms, practice patterns, and outcomes. There is a fundamental requirement for such a study. This need was recognized by EMCREG in 1999 when several of its member institutions began compiling i*trACS (the Internet Tracking Registry of Acute Coronary Syndromes). Since the registry was closed to enrollment in late 2001, subsets of the data have been used to assess health disparities, explore practice patterns, evaluate relationships between ECG results and cardiac biomarkers, and investigate the utility of diagnostic tests in subgroups such as diabetic patients and patients with heart failure.13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 However, a comprehensive description of the institutions collecting the data, the data collection methods, and of the entire cohort enrolled in the registry has yet to be provided. To facilitate use of the i*trACS database for exploring the complex interactions involved in the ED evaluation and treatment of acute coronary syndrome, we describe the data collection procedures and present a description of the entire spectrum of patients with suspected acute coronary syndrome using the standardized reporting guidelines for chest pain studies.
Section snippets
Study Design
This was a multicenter study using both direct observation and medical record review methods. Institutional review boards or ethics committees approved patient enrollment without informed consent at 8 of the 9 centers; at one center, verbal informed consent was required from the patients before data collection. At this site, no patients were known to have refused participation.
Setting
Eight sites participating in the registry were selected to represent a cross-section of providers in the United States;
Results
Throughout the 3 years, 12,390 patients suspected of having acute coronary syndrome and who had an ECG ordered by the treating physician were enrolled at one of 8 EDs in the United States. An additional 3,008 patients were enrolled in Singapore; data for these patients are available in Appendix E1 (available online at http://www.annemergmed.com). In the United States, there were 14,185 patient visits. Six patients visited the ED 10 or more times, 53 patients visited between 5 and 10 times, 55
Limitations
There are several limitations of this data set that must be accommodated by researchers using the registry. The primary limitation is the potential for bias arising from the sampling method. Although we attempted to sample as completely as possible, patients presenting overnight and on holidays were excluded at some sites. Complete capture during sampling hours is also unlikely; the practicality of obtaining a truly complete sample excluded its possibility. The most likely bias resulting from
Discussion
Several large observational studies are reported in the contemporary literature. The Global Registry of Acute Coronary Events project26 has evaluated such diverse factors as the impact of diabetes and the effectiveness of percutaneous coronary intervention, thrombolytics, and glycoprotein IIb/IIIa receptor inhibitors, as well as describing variations in practice patterns and developing risk prediction models.27, 28, 29, 30, 31 Although providing valuable insights into acute coronary syndrome in
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Cited by (0)
Supervising editor: Michael L. Callaham, MD
Author contributions: The i*trACS project was conceived and designed by CVP, JWH, JEH, JDK, WFP, BT, EKW, and WBG. CVP, VA, DD, JWH, JEH, JDK, S-HL, WFP, BT, EKW, and WBG were responsible for data collection. CJL prepared and analyzed the data, and CJL, CVP, JHH, and WBG drafted the manuscript. All authors provided critical revision of the manuscript for intellectual content. CJL had full access to the data and takes full responsibility for the integrity and analysis of the data. CJL takes responsibility for the paper as a whole.
Funding and support: The i*trACS project was supported in part by Millenium Pharmaceuticals and Schering-Plough Pharmaceuticals.
Reprints not available from the authors.