Survival and successful kidney transplant rates are significantly lower when people are obese, according to a study of over 2,000 patients published in the November issue of Transplant International.
A team of experts from across the Netherlands studied the medical profiles of 4,245 adults who had received kidney transplants, using data from the Netherlands Organ Transplantation Registry.
In 2067 cases there was sufficient information to calculate their Body Mass Index (BMI) -- based on their weight and height - at the time of their kidney transplant.
They discovered that six per cent of patients with a BMI of more than 30 died in the first year after transplant, compared with three per cent of patients with a BMI of less than 30.
By year five, the difference was even greater, with an 81 per cent survival rate for the obese patients and an 89 per cent survival rate for patients who were not obese.
The same pattern emerged when they looked at the success of the transplant itself.
A year after the transplant was carried out, 14 per cent of obese patients had experienced a transplant failure, compared with eight per cent of non obese patients.
After five years, 71 per cent of obese patients still had a successfully transplanted kidney, compared with 80 per cent of the patients with a lower BMI.
Obese patients were more likely suffer transplant failure through infection or permanent non-functioning, but the numbers for obese and non-obese patients were both fairly low.
There were no significant differences between the two groups when it came to why patients died, but there was a trend for obese patients to suffer more infections and fatal heart conditions.
Obese patients in the study group also tended to be older and were more likely to be female
"The prevalence of obesity in patients with end-stage renal disease is increasingly rapidly" says lead researcher Dr Jeroen Aalten from the Department of Nephrology at the University Medical Center in Nijmegen.
"It's estimated that 60 per cent of renal transplant candidates in the United States and 10 per cent in the Netherlands are obese or overweight.
"These figures have been rising consistently in recent years. This could be due to a general rise in obesity worldwide, but we can't rule out that it may have been affected by changes in inclusion criteria for kidney transplants."
The study -- which was carried out by Nephrology specialists from seven university hospitals across the Netherlands -- concluded that there is a significant relationship between obesity and increased transplant failure or death.
The authors acknowledge that there has been considerable debate about whether obese patients are suitable transplant candidates.
But they also point out that while obesity is preventable and fundamentally curable, compared to age and diabetes, experience shows that it can be very difficult for people with end-stage renal disease to lose weight.
"Our conclusion is that it's not fair to deny obese patients the chance of a kidney transplant as they still do better after a transplant than on dialysis" says Dr Aalten.
"However we shouldn't disregard the increased risk for obese patients after transplantation and we also need to bear in mind that it is important to give scarce resources to patients with the lowest risk.
"It is very important that patients facing kidney transplant are fully informed about the risks that they face and are encouraged to lose weight wherever possible."
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