Mortality from acute myocardial infarction is significantly higher in U.S. hospitals that treat a high percentage of black patients, according to a study published in the October issue of Circulation.
While the Institute of Medicine study on racial disparities in health and health care identified distinct differences in the treatment of diseases, particularly cardiovascular, in blacks, the mechanism driving these disparities has not been revealed, wrote the authors, led by Jonathan Skinner, PhD, of Dartmouth Medical School in Hanover, NH. Several studies have shown that black patients are treated by physicians with less clinical training, referred to lower-quality cardiac surgeons, and treated at hospitals with higher risk-adjusted surgical mortality.
The researchers conducted a prospective cohort study of fee-for-service Medicare patients hospitalized for acute myocardial infarction between January 1997 and September 2001. They classified 4,289 hospitals in deciles according to the extent to which they served the black community. Decile 10, which included 10 percent of AMI patients, encompassed hospitals with the highest fraction of black heart attack patients, 33.6 percent, while the lowest decile included the 12.5 percent of patients admitted to the 1,369 hospitals without any black AMI patients.
While patients admitted to hospitals disproportionately serving blacks experienced no greater level of morbidities or severity of the infarction, hospitals in decile 10 experienced a risk-adjusted 90-day mortality rate of 23.7 percent compared with 20.1 percent in decile 1 hospitals. Even though patients in decile 1 hospitals were the sickest, as measured by the index of comorbidities, they experienced the lowest risk-adjusted mortality after AMI. Differences in outcomes between hospitals were not explained by income, hospital ownership status, hospital volume, census region, urban status, or hospital surgical treatment intensity. Within hospitals, 90-day mortality rates for blacks were somewhat higher than for whites.
Patients admitted to hospitals with the highest fraction of black patients were more likely to live in the South and less likely to live in an urban setting. Compared with the hospital at which the average AMI patient was treated, hospitals that disproportionately treat blacks were more likely to be teaching, government, and non-profit. These hospitals were similar in terms of coronary artery bypass graft and percutaneous transluminal coronary angioplasty intensity but have lower AMI volume.