Living kidney donors show no increase in their risk of heart attacks or other cardiovascular events in the years after donation, according to the largest-ever study of the issue, presented at the American Society of Nephrology's 40th Annual Meeting and Scientific Exposition in San Francisco.
Although donors are more likely to be diagnosed with high blood pressure (hypertension) during follow-up, it is unclear whether this represents a true risk of living kidney donation, according to Lawson Health Research Institute scientist, Dr. Amit X. Garg. Dr. Garg is also an Associate Professor in Medicine and Epidemiology with the Schulich School of Medicine & Dentistry at The University of Western Ontario in London, Ontario, Canada.
Dr. Garg and colleagues analyzed follow-up data on 1,278 patients who became living kidney donors in Ontario between 1993 and 2005. Rates of major cardiovascular events -- including myocardial infarction (heart attack), stroke, angioplasty, or bypass surgery -- were compared to those of 6,369 healthy adults. To ensure comparability, the two groups were closely matched for age, sex, income, and use of health care services before donation.
During a follow-up period of one to thirteen years (average six years), 1.3 percent of the living kidney donors died or experienced a cardiovascular event. This was not statistically different from the 1.7 percent rate in the comparison group.
The only significant difference was a higher rate of hypertension among living kidney donors: about 16 percent, compared with 12 percent in the comparison group. "Donors were diagnosed more frequently with hypertension, but they also saw their primary care physicians more often than controls, and so had more opportunities to be diagnosed," says Dr. Garg. On average, the donors had one additional medical visit per year.
Living kidney donation has become an important source of organs for transplantation. However, it is essential to know the extent and nature of any health risks of donation. "Knowledge of any potential risks associated with becoming a living kidney donor would guide future donor selection, informed consent, and best practices to follow and care for living donors," comments Dr. Garg. "Risk estimates in the literature are currently quite variable, and there is global consensus that we need better estimates."
The new study refines past estimates by providing long-term follow-up data on a large group of living kidney donors -- 50 times larger than any previous study. Encouragingly, the results show no long-term increase in cardiovascular risk after donation.
Further study is needed to determine whether the apparent increase in the risk of high blood pressure is truly an effect of living kidney donation, or if it merely reflects the increased medical scrutiny after donation. "These results emphasize the importance to counsel and follow all kidney donors to manage modifiable factors in an attempt to prevent hypertension and future cardiovascular disease," adds Dr. Garg.