Patients with acute myocardial infarction (AMI) who are admitted to hospitals without coronary revascularization are frequently transferred to hospitals with this capability. We sought to determine whether the timeliness of hospital transfer and quality of destination hospitals differed between black and white patients.
We evaluated all white and black Medicare beneficiaries admitted with AMI at nonrevascularization hospitals in 2006 who were transferred to a revascularization hospital. We compared hospital length of stay before transfer and the transfer destination's 30-day risk-standardized mortality rate for AMI between black and white patients. We used hierarchical regression to adjust for patient characteristics and examine within and across-hospital effects of race on 30-day mortality and length of stay before transfer.
A total of 25,947 (42%) white and 2345 (37%) black patients with AMI were transferred from 857 urban and 774 rural nonrevascularization hospitals to 928 revascularization hospitals. Median (interquartile range) length of stay before transfer was 1 day (1 to 3 d) for white patients and 2 days (1 to 4 d) for black patients (P<0.001). In adjusted models, black patients tended to be transferred more slowly than white patients, a finding because of both across and within-hospital effects. For example, within a given urban hospital, black patients were transferred an additional 0.24 days (95% confidence interval 0.03-0.44 d) later than white patients. In addition, the lengths of stay before transfer for all patients at urban hospitals increased by 0.37 days (95% confidence interval 0.28-0.47 d) for every 20% increase in the proportion of AMI patients who were black. These results were attenuated in rural hospitals. The risk-standardized mortality rate of the revascularization hospital to which patients were ultimately sent did not differ between black and white patients.
Black patients are transferred more slowly to revascularization hospitals after AMI than white patients, resulting from both less timely transfers within hospitals and admission to hospitals with greater delays in transfer; however, 30-day mortality of the revascularization hospital to which both groups were sent to appeared similar. Race-based delays in transfer may contribute to known racial disparities in outcomes of AMI.