Hope for mismatched-blood donor kidney transplant

It’s been less than a decade since the first kidney transplant into a patient with a different blood type was performed in Singapore.

Before this, a match had always been required between recipient and donor. Faced with a growing shortage of organs, researchers were determined to develop a way to cross this barrier. By the turn of the century, trials of so-called ABO-incompatible kidney transplants, led by teams in Japan, had begun to register impressive rates of success. “ABO” refers to the different human blood types – A, B, AB, and O.

“When you’re doing a transplant, you’re bringing an organ from a stranger into the patient, and the blood-group matching is always important,” says Dr Roger Tan, a nephrologist at Gleneagles Hospital in Singapore and one of the few physicians to perform high-risk kidney transplants in the country.

“If they’re not matched, the rate of rejection is always higher. And for years the blood-group mismatch transplant was considered impossible to do. But over the last eight years or so in Singapore, we have had the technology and medicine to do such a difficult transplant successfully, and the results have been very encouraging.”

Lower rejection rate

The surgical procedure itself is the same whether or not the kidney is compatible. The difference occurs in the days before and after the transplant, when the recipient undergoes plasma exchange to clean away antibodies to prevent rejection of the organ.

The rejection rate of a mismatched kidney can be exceptionally high, although under plasma exchange this plunges to eight to 12 percent, Dr Tan says.

“So far, we’ve been quite lucky. We’ve just had one case which was easily treated with a standard anti-rejection therapy,” he explains.

Due to the plasma exchange, however, physicians are forced to use stronger medication that weakens the immunity of the recipient, leaving them at higher risk of developing infections in the short term.

In terms of the procedure itself, there is little difference between the long-term management of complex and compatible transplants. Both use immunosuppressants, and the body will accept both transplants ideally within a year.

What does vary is the difference in the level of the drugs taken, which is higher following an ABO-incompatible kidney transplant than a standard procedure.

“As is standard for transplants, patients will take immunosuppressants for the rest of their lives,” Dr Tan says. “The main thing is the doses will be reduced over time. Some may go from three to two medications, but definitely they will be on some immunosuppressants for the rest of their lives.”

The only time this will not be the case is in twin-to-twin transplants, which do not require the use of life-long medication, he says.

Not suitable for all

Not all patients are suitable for an ABO-incompatible kidney transplant. Those with underlying problems can experience additional complications from such a complex operation, including those with heart conditions where the risk may be too high.

Dr Tan says he is also reluctant to operate on elderly patients for whom quality of life is limited, such as when they are confined to a wheelchair.

“The transplant may not be ideal because you will not change their quality of life. If the transplant involves removing an organ from a healthy donor, we will always want this kidney to last longer in a patient whose quality of life is quite good. In my opinion, I don’t think it is correct to give a kidney to a bedridden patient,” he says.

Patients must also be able to afford the treatment as the surgery is still quite expensive and should have the means to afford anti-rejection medicines for the rest of their lives.

While some reports suggest that the number of kidney transplants has been increasing around the world, that is not the case in Singapore, despite efforts by the government and institutions to promote transplants over dialysis. This is because Asian patients are not so forthcoming when it comes to donating organs. “It’s always a problem finding donors here,” Dr Tan says.

Yet ABO-incompatible transplants are still having an impact on lowering the number of deaths from kidney failure, despite the dearth of available organs.

Better than dialysis

Like his peers, Dr Tan believes that every patient should receive a kidney when one becomes available even when their blood type is not the same as the donor’s. This is far preferable to relying on dialysis, which is difficult for the body to sustain.

Half of dialysis patients die within five years, despite having their blood cleaned for four hours a day, three times a week. Although the process will initially reduce toxins to an acceptable level for the patient to live, these toxins will build up in the body and their residue will still have an impact on long-term survival, with many patients developing cardiovascular complications during that period.

“In contrast, with a transplant, there is an 80-90 percent survival rate, without the complications, the inconvenience, and the suffering of dialysis,” Dr Tan says. “In such terms, transplant is far superior. That’s the view of the whole nephrologist profession.”

Dr Tan Choon Hian Roger is a nephrologist at Gleneagles Hospital in Singapore, where he specialises in kidney transplants, chronic kidney failure and hypertension. He also has a keen interest in treating autoimmune kidney conditions, such as lupus nephritis. A 1997 graduate of the National University of Singapore, he has worked in both public and private practice. Dr Tan has also served as a member of a group tasked with drafting guidelines on medical practice for Singapore’s Ministry of Health.

Roger Kidney Clinic

6 Napier road
#04-16
Gleneagles Medical Centre
Singapore

Tel: (+65) 6476 6289