Hypertension, cardiovascular disease and cause of death in Danish living kidney donors: matched cohort study

Abstract

ObjectivesWe aimed to investigate the long-term absolute risk of hypertension and cardiovascular disease after kidney donation in living kidney donors.DesignLiving kidney donors were matched to 10 controls from the general population.SettingMultiple Danish national registries were used to identify living kidney donors from 1 January 1996 to 31 December 2017 nationwide.Participants1262 living kidney donors and 12 620 controls.Main outcome measuresHypertension, cardiovascular disease and diabetes.ResultsThe median age of living kidney donors was 52 (men 43%). Hypertension developed in 50 (4%) and 231 (1.8%) with a median follow-up of 7 years (IQR 3.3–12.1 years with a maximum follow-up of 22 years) and 6.9 years (IQR 3.2–11.7 years and maximum follow-up of 22 years) for donors and controls, respectively. The absolute risk of hypertension was 2.3% (95% CI 1.4% to 3.2%) and 1.2% (95% CI 1.0% to 1.4%), 4.2% (95% CI 2.8% to 5.7%) and 2.4% (95% CI 2.1% to 2.8%), 8.6% (95% CI 6.0% to 11.3%) and 3.3% (95% CI 2.8% to 3.8%) within 5, 10, 15 years for donors and controls, respectively. The ratio of the 10-year absolute risks for hypertension was 1.64 (95% CI 1.44 to 1.88) for donors compared with the controls. Two donors and four controls developed renal replacement therapy requiring end-stage renal disease during follow-up. The absolute risk of cardiovascular disease and diabetes was 7.3% (95% CI 5.7% to 9.5%) and 8.3% (95% CI 7.7% to 9.0%), 1.7% (95% CI 0.7% to 2.8%) and 3.2% (95% CI 2.7% to 3.6%) at 10 years for donors and controls, respectively.ConclusionsLiving kidney donors have an increased long-term absolute risk of hypertension compared with controls from the general population.

The Living Kidney Donor Safety Study: Protocol of a Prospective Cohort Study

“… 11 An increased risk of hypertension in donors relative to non-donors has been reported in several studies. 11 , 13 - 17 , 33 The true risk for hypertension remains unclear, however, because studies have not defined hypertension uniformly, non-donors have not undergone the same health screening as donors, and follow-up in donors and non-donors has been dissimilar and incomplete. A better understanding of this risk is central to donor selection and consent.…”

“…Our study has some limitations. Given the limited number of events, the CIs for the estimated risk of death, kidney failure, and major cardiovascular events, 13 and for the assessment of effect modification by family history of kidney failure, will be imprecise and wide. Similarly, if the CI for our estimate of hypertension contains a value of 1.0, smaller but clinically meaningful higher risks of hypertension will likely be within the upper bound of the 95% CI (eg, an increase in risk of 25% as seen in some other recent studies).…”

“…Death, kidney failure (ie, a persistent eGFR less than 15 mL/min per 1.73 m 2 , receipt of dialysis for any duration, or receipt of a kidney transplant), and major cardiovascular events (ie, myocardial infarction, stroke, or a cardiovascular procedure such as coronary angioplasty or coronary bypass surgery) will be assessed from the annual survey and from medical records, with adjudication conducted by a physician blinded to donation status. 13 , 48 These outcomes will be assessed individually and as a composite.…”

Risk for subsequent hypertension and cardiovascular disease after living kidney donation: is it clinically relevant?

“…In general, studies have shown either a decrease or no increase in cardiovascular mortality [ 10 , 11 , 15 ]. Similarly, studies have not shown an increase in cardiovascular events or risk of developing cardiovascular disease [ 12 , 14 , 17 , 19 ]. A recent meta-analysis of four studies [ 9 , 12 , 20 , 24 ] published between 2009 and 2016 with a total of 4274 donors and 53 246 controls, and an average follow-up time ranging from 6 to 15 years, found no evidence of an increase in cardiovascular risk in donors [pooled-adjusted RR 1.11 (95% CI 0.64–1.70)] [ 23 ].…”

“…Key studies published after 2018 are summarized in Table 2 and report varying results. Some have reported a higher incidence of hypertension compared with controls [ 17 , 39 , 41 ]. Munch et al .…”