Data Resources: Introduction
This chapter reviews various data sources available for observational research, examines their strengths and limitations, and identifies opportunities for further improving observational databases by integrating data collected from different sources. The focus is on observational research using existing databases.
Clinical registries have an important role in observational research. In this section, we first review an array of the available clinical registries that are closely or broadly relevant to cardiovascular disease (Table 11–1). We then summarize the strengths and limitations of clinical registries for observational study.
Database | Size | Examples |
|---|---|---|
Clinicians’ own experiences | 10–100s | Osler, Harvey |
Single center databases | 1000–10,000s | Duke Databank for Cardiovascular Diseases Emory Cardiac Database |
Epidemiological cohorts | 10,000s | National Heart, Lung, and Blood Institute Dynamic Registry |
National registries | Millions | American Heart Association Get With The Guidelines American College of Cardiology National Cardiovascular Data Registry Society of Thoracic Surgeons National Database |
Global registries | Potentially billions | Global Registry of Acute Coronary Events (GRACE) ProspeCtive observational LongitudinAl RegIstry oF patients with stable coronary arterY disease (CLARIFY) |
Get With The Guidelines® (GWTG) is a national cardiovascular disease registry and quality improvement program developed by the American Heart Association (AHA) and American Stroke Association. The GWTG registry includes three modules—one each for coronary artery disease, heart failure, and stroke (1)—and one outpatient program (2). GWTG uses a Web-based patient management tool (Outcomes, Cambridge, MA) to abstract detailed clinical data, including patient demographics, medical history, symptoms on arrival, in-hospital treatment and events, contraindications to medications, laboratory findings, discharge treatment and counseling, and patient disposition from more than 381,000 patients in the heart failure module and more than 1,000,000 patients in the stroke module. In 2008, the coronary disease module was merged with the American College of Cardiology (ACC) Acute Coronary Treatment and Intervention Outcomes Network (ACTION®) registry to form the National Cardiovascular Data Registry (NCDR) ACTION Registry–GWTG, which has become the most comprehensive data source for acute coronary syndromes in the United States (3). In 2011, the GWTG outpatient program was expanded to become The Guideline Advantage™, in collaboration with the American Cancer Society and American Diabetes Association (2).
This is a comprehensive outcomes-based quality improvement program operated by the ACC since 1997 (4). More than 2,200 hospitals participate in the NCDR across the United States. The NCDR includes the outpatient Practice INNovation And CLinical Excellence (PINNACLE) registry, with more than 1.5 million records, and various hospital-based registries, including ACTION Registry–GWTG, for patients with high-risk myocardial infarction; CathPCI, for cardiac catheterizations and percutaneous coronary intervention procedures; the ICD Registry, for tracking implantable cardioverter defibrillator procedures; the CARE Registry, for carotid artery stenting and endarterectomy; and the IMPACT registry, for pediatric and adult patients with congenital heart disease who are undergoing diagnostic catheterization and interventions.
Can Rapid risk stratification of Unstable patients with angina Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines? (CRUSADE) is a clinical registry of more than 200,000 patients with acute coronary syndromes at 600 hospitals in the United States (5). Data collected include patient risk factors, presenting symptoms, use of medications/invasive procedures, and in-hospital clinical outcomes focused on the ACC/AHA guidelines.
This is the largest cardiothoracic surgery quality improvement and outcomes database in the world (6). The society provides clinical details and outcomes for more than 4.3 million coronary artery bypass graft surgeries and valvular and other cardiac procedures from 1,014 participating sites in the United States.
The Acute Decompensated Heart failurE national REgistry (ADHERE) is an industry-sponsored, multicenter, national registry evaluating the characteristics, management, and clinical outcomes of patients hospitalized with acute decompensated heart failure (7). More than 150,000 patients from 300 community and academic centers in the United States were enrolled between 2001 and 2006.
The Organized Program To Initiate life-saving treatMent In hospitaliZEd patients with Heart Failure (OPTIMIZE- HF) is a national registry designed to evaluate and improve guideline adherence among hospitalized patients with heart failure (8). Unlike ADHERE and many other clinical registries reporting only in-hospital events, OPTIMIZE-HF captures outcomes data at 60 and 90 days after discharge for selected patients (10%). The OPTIMIZE-HF project transitioned to GWTG-HF in 2005.
The Prospective Registry Evaluating Myocardial Infarction: Event and Recovery (PREMIER) (9) and Translational Research Investigating Underlying disparities in acute Myocardial infarction Patients’ Health status (TRIUMPH) (10) are prospective multicenter registries of 7000 patients with acute myocardial infarction (2,500 in PREMIER and 4,500 in TRIUMPH). A distinct feature of PREMIER and TRIUMPH is that patient-centered outcome measures, including symptoms, functional status, and quality of life, are collected at 1, 6, and 12 months after the index hospitalization.
Among the most important strengths of clinical registries are broader population coverage, solid exposure and outcomes measures, and rich clinical data available to adjust for confounding variables. Clinical registries tend to include a large number of patients; registry-based findings therefore can be more generalizable to a wide range of patients than can those from randomized controlled trials (RCTs), which contain more homogenous populations in ideal situations. Exposure/treatment and outcomes/effectiveness are better defined in a registry than in administrative data. Additionally, rich clinical information, such as risk factors and comorbid conditions, can be used to build precise risk-adjustment models. Finally, clinical registries provide an opportunity to evaluate the effectiveness of interventions in cases in which randomization is unethical or impractical (e.g., studies of surgical procedures).
Despite the clear strengths of clinical registries, several limitations should be noted. Unlike in clinical trials, in which patients are randomized to either a treatment or a control arm, outcomes assessment using registry data can be subject to selection bias. In addition, registries are often limited in terms of their targeted population. Unlike hospital administrative data, a clinical registry often focuses on certain diseases and conditions. For instance, it is unrealistic to use a stroke registry for cancer research. Another drawback of many clinical registries has been the lack of follow-up data beyond hospital discharge or the acute episode of care. Knowledge obtained in hospital may not be applicable to intermediate or long-term outcomes. Methods have been developed to address this limitation by linking clinical registry data with external data sources. These strategies are discussed later in this chapter.
