Ask any typical renal patient waiting for a transplant
why they're so desperate for that new kidney and you're
likely to hear the same word over and over again: independence.
They simply want an end to the constant routine of hospital
visits for hemodialysis or the time-consuming rigmarole
of peritoneal dialysis, even if it means accepting the
considerable risks that go along with transplantation.
Now transplant recipients have
more than just independence to look forward to. New
research is starting to prove that an even bigger pot
of gold lies at the end of the transplant waiting list
— a major increase in life expectancy.
DOUBLE,
TRIPLE, HOME RUN
Early comparisons of dialysis to cadaveric transplantation
showed little survival benefit from a new kidney, but
advocates of transplantation argued that these studies
were skewed because they effectively measured dialysis
patients from the time of diagnosis, while measuring
transplant patients from the time of surgery.
More recent results from the US,
using better methodology, suggested a doubling of life
expectancy in transplant recipients. Now, Scottish research
from the June issue of the Journal of the American
Society of Nephrology appears to show that patients
who get their transplant can expect to live three times
longer, on average, than patients who remain on dialysis.
Researchers from the New Royal
Infirmary of Edinburgh followed the progress of all
1,732 patients listed for a first cadaveric transplantation
in Scotland between 1989 and 1999. Of these, 1,095 got
their new kidney during the study period. Since that
time, the researchers have calculated that the patients
who received a new kidney have had an average life expectancy
of 17.19 years, while those who remained on dialysis
had an average life expectancy of 5.84 years. To put
it another way, most of the transplant recipients are
still alive, and most of the dialysis patients are now
dead.
The greatest survival benefit was
seen in the 50 to 59 age group, while the smallest benefit
was in patients aged 18 to 34 because they tended to
survive even on dialysis. In fact, patients aged 65
and older saw a bigger increase in life expectancy from
transplantation than this youngest age group.
OPERATION:
RISK
Naturally, an operation as dramatic as a kidney transplant
carries its own risks. In the first month after transplant,
patients ran a risk of death 35% higher than those who
remained on dialysis. But by the 18-month mark, their
risk of death was already dramatically lower, just 18%
of the risk in the dialysis group.
The findings of the Edinburgh study
are complicated, however, by the vagaries of the transplant
system, which operates a sort of triage based on doctors'
assessments of patients' chances. There were marked
differences between the patients who got their transplant
and those who languished on the waiting list. The transplant
recipients had an average age of 43, ten years younger
than the dialysis patients. They were less likely to
smoke, and only about half as likely to have a range
of cardiovascular disorders. Logically, adjustment for
these factors should reduce the benefit shown from transplant,
but in this study it seemed to increase the benefit.
In the absence of the raw data, some might question
how this finding was reached.
In Canada, the overall number of
kidney transplants has remained fairly steady in recent
times, at about 1,000 a year. The number of cadaveric
donors has also remained steady, at about 400 a year.
But since that is not enough to meet demand, waiting
lists have grown. The result has been an increase in
living donors, from about 200 a year a decade ago to
400 a year today. Cadaveric transplants still outnumber
living donor transplants, however, for the simple reason
that living people can only spare one kidney while cadavers
can yield two.
J Am Soc Nephrol June, 2005;
16 (6):1859-65
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