Correspondence

The Relation between Experience and Outcome in Heart Transplantation

N Engl J Med 1993; 328:514-515February 18, 1993

Article

To the Editor:

Although it is of historical interest, the paper by Laffel et al. (Oct. 22 issue)1 is of limited contemporary relevance. It reflects nothing more than the importance of the “period effect” in the assessment of forms of medical technology. Since 1987 there have been remarkable developments related to the provision of heart-transplantation services in the United States2-4. These include the implementation of criteria for transplantation programs by the United Network for Organ Sharing, the designation of transplantation centers by third-party payers, and the certification of transplantation personnel by appropriate professional associations (e.g., the North American Transplant Coordinators Organization)5-7. Each of these developments has been intended to enhance the outcomes of transplant recipients.

In a recent analysis of 1988 data, we too examined the “experience hypothesis” as it relates to kidney, heart, and liver transplantation8-10. We used three measures of experience -- the total volume of a program, the experience of individual surgeons (i.e., the number of transplantations performed), and the experience of physicians (i.e., the number of years involved in the care of transplant recipients after transplantation). Using a discrete piecewise exponential hazards model, we concluded, after adjusting for patient mix and other institutional covariates, that experience, however it was measured, had both a statistically insignificant and a clinically unimportant effect on the survival of heart-transplant recipients. The two most important predictors of an adverse outcome were the use of an artificial device as a bridge to transplantation and the need for a second transplantation10.

On the basis of our results, we concluded that transplantation professionals, as well as members of the insurance industry, have taken steps that have ensured the quality of transplantation services. Because all hospitals must now have experienced personnel before they can effectively begin a transplantation program, we believe that the learning curve described by Laffel et al. is an artifact of the period their data represent. Sadly, they have used historical data to create a contemporary misconception that may, in turn, unjustifiably handicap new heart-transplantation programs. There are simply no data to suggest that the experience of surgeons, physicians, nurses, and transplantation coordinators is attenuated as a result of geographic relocation. Thus, appropriate safeguards are now in place to ensure that even new heart-transplantation programs will offer high-quality services. We therefore recommend that third-party payers base the designation of transplantation centers on the experience of individual team members, rather than on the number of transplantations a program performs annually.

Roger W. Evans, Ph.D.
Mayo Clinic, Rochester, MN 55905

10 References

1. 1

   Laffel GL, Barnett AI, Finkelstein S, Kaye MP. The relation between experience and outcome in heart transplantation. N Engl J Med 1992;327:1220-1225
   Full Text | Web of Science | Medline

2. 2

   Monaco AP. Problems in transplantation -- ethics, education, and expansion. Transplantation 1987;43:1-4
   CrossRef | Web of Science | Medline

3. 3

   Corry RJ. Recommendations regarding issues facing organ transplantation. Transplantation 1988;45:259-261
   CrossRef | Web of Science | Medline

4. 4

   Task Force on Organ Transplantation. Organ transplantation: issues and recommendations. Rockville, Md.: Health Resources and Services Administration, April 1986.
   

5. 5

   Ascher NL, Evans RW. Designation of liver transplant centers in the United States. Transplant Proc 1987;19:2405-2405
   Web of Science | Medline

6. 6

   Evans RW. Public and private insurer designation of transplantation programs. Transplantation 1992;53:1041-1046
   CrossRef | Web of Science | Medline

7. 7

   Renlund DG, Bristow MR, Lybbert MR, O'Connell JB, Gay WA Jr. Medicare-designated centers for cardiac transplantation. N Engl J Med 1987;316:873-876
   Full Text | Web of Science | Medline

8. 8

   Evans RW, Manninen DL, Dong FB, eds. The National Cooperative Transplantation Study: final report. Seattle: Battelle Seattle Research Center, June 1991.
   

9. 9

   Evans RW, Manninen DL, Dong FB. The center effect in kidney transplantation. Transplant Proc 1991;23:1315-1317
   Web of Science | Medline

10. 10

    Evans RW, Manninen DL, Dong FB. The center effect in heart transplantation. In: Terasaki PI, Cecka JM, eds. Clinical transplants, 1991. Los Angeles: UCLA Tissue Typing Laboratory, 1991:45-59.
    

Author/Editor Response

Dr. Laffel replies:

To the Editor: We studied data from 1984 through 1986 in order to provide empirical support for the regulations and policies referred to by Dr. Evans. Our results generally support personnel-based policies that went into effect around 1986, but they suggest that these policies can be extended to include requirements for transplantation coordinators (as well as physicians). Furthermore, our results are consistent with those of Evans in suggesting that current experience-based policies for hospitals (such as the Medicare criteria for designating heart-transplantation centers) are too rigid. These criteria can be relaxed without jeopardizing outcomes at new centers.

We are concerned that Evans' group did not find institutional learning curves to be present in 1988, since we found them to be present in all three years of our study, with no dampening of the effect as the years went by. Since we did not observe a dampening of the learning-curve phenomenon, we find it difficult to accept the assertion that our differing results reflect different “eras” in the evolution of modern heart transplantation. We prefer to believe that these results reflect differences in the ways our two groups defined experience and in the methods we used to detect its effects. We believe our method of detecting learning curves is highly sensitive. It should be possible to study this issue by comparing both methods in the study of a single set of data.

In any case, we cannot help but think that Dr. Evans may have failed to grasp the primary purpose of our paper, which was to help policy makers make rational decisions about emerging techniques, such as lung, small-bowel, pancreas, and partial liver transplantation. No one disputes that heart transplantation has matured to the point at which the incremental effects of experience are no longer as important as they once were. The point is that, as with heart transplantation at about 1985, these forms of technology stand poised to become diffused explosively before providers gain much experience with them. This situation has given us a rare opportunity to provide genuine empirical support for policy makers, so that they can formulate rational policies for the use of the new techniques. From our study of Dr. Evans' work over the years, we assume that he supports this sort of endeavor.

Glenn Laffel, M.D., Ph.D.
Brigham and Women's Hospital, Boston, MA 02115

Citing Articles (2)

Citing Articles

1. 1

   I. Zupan, B. Vrtovec, U.D. Breskvar, T. Gabrijelčič. (2005) Noninvasive monitoring of rejection therapy based on intramyocardial electrograms after orthotopic heart transplantation. Initial experience with 14 cases. International Immunopharmacology 5:1, 59-65
   CrossRef

2. 2

   Steven H. Belle, Katherine M. Detre, Kimberly C. Beringer. (1995) The relationship between outcome of liver transplantation and experience in new centers. Liver Transplantation and Surgery 1:6, 347-353
   CrossRef