We found, as have others,1, 3, 11, 32, 33
that hospitals with higher teaching intensity appear to have lower risk-adjusted mortality after major surgery than less teaching intensive hospitals. Previous studies have shown similar or higher postoperative complication rates at teaching hospitals than at non-teaching hospitals.34–38
We now demonstrate that the lower mortality rates in surgical cases are mediated by fewer deaths among patients who experienced complications (lower FTR) and not by lower rates of complications. Moreover, this finding does not change when adjustments are made for ZIP code level income, suggesting that lower FTR rates in this population are not generated by unequal access to higher teaching intensity hospitals by patients of different incomes.
It is therefore of interest to find, when using data from the entire Medicare population in the United States, that blacks, unlike whites, do not experience lower surgical mortality and FTR rates at teaching intensive hospitals. It appears that blacks fare about equally well in teaching and non-teaching hospitals, whereas whites have significantly better risk adjusted mortality and FTR at teaching hospitals than at non-teaching hospitals.
Why does this racial disparity in mortality and FTR exist? It is noteworthy that this disparity is smaller, though still substantial, in the model with a separate fixed effect for each hospital. This indicates that some, but by no means all, of the disparity stems from blacks going to teaching hospitals with similar RB ratios but worse mortality and FTR rates than their white counterparts (a similar effect was reported by Lucas et al.39
and Barnato et al.40
). However, our study found that the within-hospital disparities are large, significant, and more substantial than those observed in previous work.13, 40–42
In earlier work we also have studied racial differences in the length of surgery for comparable procedures, and found lower income black Medicare patients had surgery that took on average 29 minutes longer than whites of similar income (P < 0.0001). In part this was because blacks tended to go to teaching hospitals that had longer procedure times.43, 44
However, even when adjusting for the individual hospital, procedure time remained significantly longer in blacks, but now by 7 minutes (P < 0.0001). Inside some very major teaching hospitals the black-white difference was not apparent, while in others the difference was more than 16 minutes for comparable surgery. The observed racial disparities in adjusted procedure length raises questions as to whether there are potential differences in who provides care to these populations at teaching-intensive hospitals.
Why racial differences in FTR should occur within hospitals is not well understood, but there are many possibilities. Chan et al.45
report that black patients were 22% (P < 0.009) more likely to experience a delay in initiating defibrillation than their white counterparts, with arrests occurring in unmonitored beds more often than whites (P < 0.001). Are black patients being monitored in the same way as their white counterparts? In search of a more general cause, Balsa and McGuire have described a process of “statistical” discrimination in which unintentional actions potentially based on poor communication may lead to disparities in outcomes. 46
This could be exacerbated in time-pressured environments in which relatively inexperienced providers deliver much of the care. Unintentional differences in communication47
might lead to less appropriate or less accurate monitoring of black patients, or less involvement in their care by personnel who could make a difference in reducing FTR. In our previous work we considered the possibility that the differences in surgical procedure length between whites and blacks may be due to different levels of involvement of physicians-in-training in black versus white patients.43, 44
How does the difference in income between blacks and whites relate to the disparity in FTR? This is a complex issue because these are Medicare, non HMO, patients and, in principle, income should not be a factor in care, though gaps between principle and practice might occur. We did adjust for median income within the ZIP code of residence, and after adjustment, teaching intensive hospitals still have lower FTR than non-teaching hospitals in whites but not blacks, suggesting that the apparent benefit of teaching intensity is not an artifact of unequal income.
It also was interesting to observe that at non-teaching hospitals, blacks actually had slightly lower overall adjusted mortality than whites, although the crude mortality rates were higher for blacks than whites in non-teaching hospitals.48–51
We would not want to make too much of our finding since the coefficient on the race difference in non-teaching hospitals was small (an odds ratio of 0.96) and recent work by Volpp et al.49
and Polsky et al.,50
report that black patients were noted to have lower 30-day mortality than whites for a number of conditions, but this reversed with longer follow-up.
It is important to note limitations to our study. Although we report on a very large sample size based on Medicare claims data, the tradeoff is that these records do not contain chart-based data. For example, we do not have details on the sequencing or severity of complications and do not know whether subgroups in this study had a different distribution of complications that may partially explain our findings.52, 53
Relying on claims data, and not chart review, does leave open the possibility that racial differences in mortality and failure-to-rescue may be due to unmeasured severity. However, it should be noted that our study compared whites at less teaching-intensive hospitals to whites at more teaching-intensive hospitals, and the same for blacks. Hence, for our severity adjustment to be inadequate it would need to be the case that even after our extensive risk adjustment, whites entering teaching hospitals are in better health than whites entering non-teaching hospitals, but blacks entering teaching hospitals are in the same health as blacks entering non-teaching hospitals. If blacks were sicker than whites in the same unmeasured ways upon admission to all hospitals, this by itself would not produce the pattern of mortality and FTR rates that we found.
In conclusion, teaching intensive hospitals with high RB ratios have lower risk adjusted mortality rates after major surgery than hospitals with lower ratios or without residents. This better survival is mainly due to better failure-to-rescue rates after postoperative complications. However, on average, while whites have lower mortality and failure-to-rescue rates at teaching intensive hospitals, blacks do not.