Cardiovascular disease in kidney donors: matched cohort studyBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e1203 (Published 01 March 2012) Cite this as: BMJ 2012;344:e1203
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Garg and colleagues have provided important new data which contributes significantly to our understanding of the long-term consequences of living kidney donation (1). Whilst the authors should be commended for attempting to match the donor participants with the non-donor controls, it is hard to determine whether the groups were truly comparable for there is a lack of any information on blood pressure (BP).
A widely quoted meta-analysis from the same group reported an increase in systolic BP of approximately 5 mmHg in kidney donors approximately 10 years after nephrectomy (2). Taken together these data suggest that blood pressure rises significantly following kidney donation but without an accompanying increase in cardiovascular morbidity or mortality (1, 2). If this finding is confirmed, kidney donors would be the only group of patients yet studied, in which a rise in BP has not been accompanied by an increase in mortality. Indeed, in the general population, even a 2 mmHg increase in systolic BP confers a long-term increase in mortality from stroke and cardiovascular disease of 10% and 7%, respectively (3). Thus, it is likely that either the data on BP or on morbidity and mortality in kidney donors are incorrect.
Nevertheless, even if adverse changes in BP were detected this should not be regarded as a major negative finding, given that they can be so easily treated. The hidden danger is that in our well-motivated desire to improve outcomes in patients with established renal failure we falsely reassure ourselves that we have not adversely affected the donor. In order to safeguard the expanding practice of living kidney donation, we suggest that, henceforth, all donors should be invited to participate prospectively in pathophysiological as well as epidemiological studies.
1. Garg AX, Meirambayeva A, Huang A, Kim J, Prasad GV, Knoll G, et al. Cardiovascular disease in kidney donors: matched cohort study. Bmj 2012;344:e1203.
2. Boudville N, Prasad GV, Knoll G, Muirhead N, Thiessen-Philbrook H, Yang RC, et al. Meta-analysis: risk for hypertension in living kidney donors. Ann Intern Med 2006;145(3):185-96.
3. Lewington S, Clarke R, Qizilbash N, Peto R, Collins R. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002;360(9349):1903-13.
Competing interests: No competing interests
We are grateful to Garg AX et al for their study informing the discussion on long-term repercussions of donor nephrectomy (1). We are reassured that their population did not evidence increased risk when compared to matched non-donors in the general population. The recent meta-analysis described in the discussion (2) correlates increased cardiovascular risk with lower GFR in the general population. It is unclear whether the same applies to the donor population; low GFR due to chronic kidney disease compared with low GFR due to donor nephrectomy may well lead to different health outcomes. Hence, it is still an open question as to whether cardiovascular risk stratification by GFR remains true for people with a solitary kidney.
To our disappointment, the authors did not have access to donor GFR and were not able to report these data in the study. We believe that there is a medical, if not ethical, duty to ensure monitoring of GFR post-donation (as well as proteinuria and blood pressure) is standard practice and that these data are accessible for ongoing audit of living kidney donation practices. Garg et al note that transplant centres use different acceptance criteria for living donors. As the pressure for organs increases, these criteria may be expanded. It is crucial that we do not compromise donor health in our desire to improve recipient outcomes. We look forward to the establishment of large living donor registries (3, 4) and further studies to aid our understanding of donor renal and non-renal outcomes in the future.
1. Garg, AX et al. Cardiovascular disease in kidney donors: matched cohort study. BMJ 2012; 344: e1203
2. Matsushita K et al. Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis. Lancet 2010; 375:2073-81.
3. ANZDATA LKDR, www.anzdata.org.au
4. Hartmann A et al. The risk of living kidney donation. Nephrol Dial Transplant 2003; 18: 871-873
Competing interests: No competing interests