Are registry hospitals different? A comparison of patients admitted to hospitals of a commercial heart failure registry with those from national and community cohorts

Background Clinical registries have been created to address questions that are difficult to answer with clinical trials. However, the applicability of registry findings to the genera I population has been questioned because of concerns over potentia I bias in the selection of participating hospitals. The purpose of this study was to determine if patients admitted to hospitals participating in a heart failure registry (ADHERE) are comparable with patients admitted to other hospitals, including those admitted to Framingham area hospitals. Methods We used a 20% random sample of all Medicare patients discharged during 1984 to 2001 to determine rates of hospitalization, procedure use, and survival after a first admission for heart failure (none in the prior 3 years). Hospitals were classified as participating in the ADHERE registry (n = 189), located within or near Framingham, MA (n = 9), or other (n = 5541). Results A total of 725702 first admissions were identified, including 80338 to ADHERE hospitals and 1716 to Framingham area hospitals. Minimal differences in patient characteristics were noted between patients admitted to ADHERE and non-ADHERE hospitals, although patients admitted to Framingham area hospitals were more likely to be white (95%) than were patients admitted to ADHERE (84%) orother hospitals (87%, P <.0001). Mortality at 1 year was 35.8% for ADHERE, 36.2% for other hospitalized patients, and 32.9% for Framingham patients (P <.0001). Rehospitalization for heart failure at 90 days was 13.0% for following admission to ADHERE, 13.0% to other hospitals, and 16.4% to Framingham hospitals (P=.0004). After adjustment for patient characteristics, differences in outcome between ADHERE and non-ADHERE hospitals remained minimal. Conclusion Patients admitted with heart failure to ADHERE registry hospitals had similar baseline characteristics and outcomes to other patients.