Summer 1996 Volume 3, Number 1

THE SAFETY OF THE DONOR ORGAN SUPPLY

What Are the Risks?

The rapid growth of solid organ transplantation over the last decade has created shortages in organ supply that have reached crisis levels worldwide. Efforts to expand the donor pool, although essential, have raised concern regarding the safety of donor organs. Clearly, proper biological allograft function is the sine qua non of successful transplantation. But the transplantation team must also assure recipients and their families that diseases (infectious or neoplastic) are not transmitted from donors (most often cadaveric, but increasingly living donors as well) to recipients. Risk is heightened in this era of multiple recipients of solid organs and tissues from a single donor.

A donor's medical and social history serve as the first and most important screen in preventing donor to recipient disease transmission. Certain risk factors (homosexual men, intravenous drug users, prostitutes, current/
recent prisoners) can be classified as "life-style" or "social history"-based. Others (prior hepatitis, hemophilia) fall into the "medical history" category and carry the potential for transmission of viral diseases including hepatitis B, hepatitis C, and HIV. A medical history (negative or positive) should always be accompanied by a careful physical examination which may reveal evidence of high-risk behavior (ie, track marks) or possible malignancy (see below).

Despite the extraordinarily high specificity and sensitivity of antibody/antigen screens for these diseases, reports of possible viral transmission of hepatitis B and C among solid organ recipients are emerging. The use of organs from hepatitis antibody-positive donors (core or surface) remains controversial. Some transplant centers accept kidneys only from these donors; others accept livers also, particularly in the case of an extremely ill recipient. Likewise, organs from donors with hepatitis C antibody positivity are placed by some centers into recipients who are already seropositive for this virus. Outcomes from these transplants are being closely monitored as these policies continue to evolve.

Increasingly, HIV antibody screens shorten the window of time from viral exposure to antibody detectability. A newly available HIV antigen test for p-24 protein may have a role in screening high-risk donors and allowing use of organs from high-risk social groups which may otherwise have been discarded. The use of this test is projected to detect 6 to 12 infectious blood units annually in the United States that might have been missed by HIV antibody testing.^1,2 Applying this technology to organ donor testing may provide extra assurance of the safety of that organ. More importantly, it may allow the transplant surgeon or physician to accept organs from high-risk donors when recent exposure to HIV is considered very unlikely. In general, the HIV p-24 protein is detectable within three weeks of infection. A high false positive rate, however, may reduce the value of this test. Furthermore, current technology does not allow this test and its confirmation to be completed within a few hours' time, the typical time window necessary in organ donation work.

In reality, even prior to the recent advances in HIV antibody and antigen testing, only seven instances of donor to recipient HIV transmission have been documented between 1988 and 1992. All seven organs came from the same donor. During this period 66,284 recipients were transplanted, giving an infection rate of 0.006 percent. These data highlight the excellent record of the transplant community in the prevention of HIV transmission.

Another safety concern is the potential for transmitting a malignancy from the donor to the recipient. Here again, the first and most important screen against this threat is a careful history from a knowledgeable family member and a detailed physical exam. A donor with any recent malignancy other than non-melanoma skin cancer should be approached with caution, but a remote malignancy, of which the donor can be considered cured, should not prevent organ acceptance. Many donors undergo extensive medical imaging prior to organ donation. A careful exploration of the chest and abdominal cavities at the time of organ retrieval presents another opportunity to uncover an occult cancer. Of course, the precarious status of the particular recipient (in the case of lifesaving transplantation) may compel the transplant center to be more lenient in donor selection.

Reports of donor-derived malignancy diagnosed in the recipient are exceedingly rare.^3,4 Indirect evidence of the safety of the donor organ from a malignancy standpoint comes from transplant registries. With tens of thousands of patients transplanted, only skin cancers and lymphomas occur at a higher incidence in transplant recipients than they do in the general population. Common cancers (lung, breast, colon, prostate) are no more frequent in the transplant population. In general, potential donors with known malignancies are precluded from organ donation. A rare exception is made for patients who die from primary central nervous system tumors which are well differentiated, slow-growing, and known not to spread outside the skull. Donor organ acceptance, though, is always considered in the light of the urgency of the potential recipient's illness.

Bacterial and treponemal (syphilis) infections are routinely screened for in the potential organ donor. Even active syphilis, however, is not an obstacle to donation if both the donor and the recipient are treated. Bacterial infections with negative blood cultures are also not generally problematic, given proper antibiotic treatment in the donor and coverage in the recipient. Some infections (ie, meningococcal) do require adequate duration of therapy prior to organ donation.

With tens of thousands of patients transplanted, only skin cancers and lymphomas occur at a higher incidence in transplant recipients than they do in the general population. Common cancers (lung, breast, colon, prostate) are no more frequent in the transplant population. In general, potential donors with known malignancies are precluded from organ donation.

In summary, recent experience demonstrates that the organ supply in the United States is extremely safe. Proper donor screening and advances in serologic testing over the last two decades have significantly reduced the transmission of infection from donor to recipient. Nevertheless, with increasing utilization of tissues and organs from high-risk donors, innovative strategies will be needed to ensure the continued safety of the organ supply and a proper balance between donor organ quality and recipient need.

Marlon F. Levy, MD
Department of Surgery
Baylor University Medical Center
Dallas, Texas

REFERENCES

1. Sloand EM, Pitt E, Klein HG. Safety of the blood supply. JAMA 1995;274(17):1368-1373.
2. Lackritz EM, Satten GA, Aberle-Grasse J, Dodd RY, Raimondi VP, Janssen RS, et al. Estimated risk of transmission of the human immunodeficiency virus by screened blood in the United States. N Engl J Med 1995;333(26):1721-1725.
3. Penn I. Occurrence of cancers in immunosuppressed organ transplant recipients. In: Clinical Transplants 1990, Terasaki P, editor. Los Angeles, UCLA Tissue Typing Laboratory 1990, pp 53-62.
4. Penn I. Malignant melanoma in organ allograft recipients. Transplantation 1996;61(2):274-278.

Back to Top · Return to Contents

Please be aware that medical advice, diagnoses and physician references cannot be obtained from this site.