Correspondence

Cost Effectiveness of Coronary Bypass Surgery versus Angioplasty

N Engl J Med 1997; 336:1840-1841June 19, 1997

Article

To the Editor:

Hlatky et al. (Jan. 9 issue)1 performed a cost-effectiveness analysis of data derived from a subgroup of the Bypass Angioplasty Revascularization Investigation (BARI) study, a randomized trial comparing coronary-artery bypass surgery with coronary angioplasty. After five years of follow-up, they found that the costs associated with bypass surgery were $2,664 higher than those associated with angioplasty. Noting that patients assigned to bypass surgery had “slightly better average survival rates (0.10 life-year),” they calculated a cost-effectiveness ratio of $26,117 per year of life added by surgery.

In fact, this study revealed no significant difference in survival between the patients randomly assigned to angioplasty and those randomly assigned to bypass surgery (except among patients with diabetes, not the subject of the analysis presented here). The authors state that “the patients in the angioplasty group [had] a slightly higher mortality rate (P = 0.54),” but the P value indicates that this result could well be due to chance.

A calculated cost-effectiveness ratio of $26,117 per year of life added by surgery is questionable when the data in the same population fail to show a significant survival benefit for surgery at all.

Michael W. Jacobson, M.D., M.P.H.
Lenox Hill Hospital, New York, NY 10021

1 References

1. 1

   Hlatky MA, Rogers WJ, Johnstone I, et al. Medical care costs and quality of life after randomization to coronary angioplasty or coronary bypass surgery. N Engl J Med 1997;336:92-99
   Full Text | Web of Science | Medline

Author/Editor Response

Dr. Hlatky replies:

To the Editor: In clinical studies, there is a well-recognized distinction between the concepts “statistically significant” and “clinically important.” The absolute survival difference of 2.9 percentage points between angioplasty and bypass surgery after five years in the BARI study was of marginal statistical significance owing to the sample size of 1829 patients. The cost-effectiveness analysis, however, suggests that a survival difference of this magnitude may indeed be clinically important despite the lack of nominal statistical significance. The differences in survival and cost measured in a randomized trial provide the best available evidence about cost effectiveness, and the bootstrap analysis reported in our paper gives the reader information about the range of cost-effectiveness ratios that are consistent with the data. We believe this information is useful for clinical decisions.

The variation in the cost effectiveness of surgery relative to angioplasty according to the characteristics of the patient was also a key finding in our study. We found that on average surgery was more cost effective in patients with three-vessel coronary disease, diabetes, or both, and that it was less cost effective in patients with two-vessel coronary disease. This variation according to clinical characteristics suggests that using a single number for the cost-effectiveness ratio is insufficient to characterize the value of surgery relative to that of angioplasty in multivessel coronary disease. The patients who are better suited than average for surgery and those who are better suited for angioplasty can be identified at the time their initial therapy is selected.

Mark Hlatky, M.D.
Stanford University School of Medicine, Stanford, CA 94305

Citing Articles (1)

Citing Articles

1. 1

   M. F. Botteman, M. Meijboom, I. Foley, J. M. Stephens, Y. M. Chen, S. Kaura. (2011) Cost-effectiveness of zoledronic acid in the prevention of skeletal-related events in patients with bone metastases secondary to advanced renal cell carcinoma: application to France, Germany, and the United Kingdom. The European Journal of Health Economics 12:6, 575-588
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