In 2 recent CMAJ articles[1, 2] we reported a favourable national trend of decreasing risk-adjusted rates of death after coronary artery bypass graft (CABG) surgery over 4 fiscal years - 1992/93 through 1995/96. The 17% relative decline in adjusted death rates over this period was judged to be comparable to the declines seen over similar periods in various regions of the United States.[3–6] We now briefly report results of more recent analyses that include data from 2 additional fiscal years, 1996/97 and 1997/98.
The updated results (Table 1) were generated using hospital discharge data from the Canadian Institute for Health Information. This data source provides information on CABG surgery cases from all provinces except Quebec. We performed risk adjustment analyses to control for differences in average severity of illness across years using the methods described in our original articles.[1, 2]
These data demonstrate a steady increase in the number of CABG procedures performed each year and continuing improvement in both observed and adjusted death rates after CABG surgery, despite a concomitant increase in expected death rates. The latter suggests that, on average, patients selected for CABG surgery are becoming sicker and their cases more complex, and yet they are more likely to experience favourable short-term outcomes after surgery. The 29.5% relative decline in risk-adjusted death rates seen over 6 years is unlikely to be the result of "upcoding" of severity of illness, because the coding of hospital discharge data is not done by the clinicians who care for the patients and because the observed death rates (which are not subject to coding biases) also dropped considerably.
Although the reasons for the improved outcomes are not clear from our analyses, we would nonetheless propose that collective congratulations ought to be extended to the community of cardiologists, intensivists, anesthetists and cardiac surgeons who care for these patients.
References
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.