Is the Risk of Cardiovascular Disease Increased in Living Kidney Donors?

A Danish Population-Based Cohort Study

Philip Munch; Christian Fynbo Christiansen; Henrik Birn; Christian Erikstrup; Mette Nørgaard

Disclosures

American Journal of Transplantation. 2021;21(5):1857-1865. 

In This Article

Results

Patients' Characteristics

For comparison with the general population cohort, we identified 1,325 kidney donors. After application of the exclusion criteria 1,103 (83.2%) kidney donors remained and were eligible for analysis. Among the 222 excluded kidney donors, 19 had a previous diagnosis of cancer, 14 had a previous diagnosis of angina pectoris, 15 had a previous diagnosis of COPD, 18 had a previous diagnosis of autoimmune disease, while 152 had a redeemed prescription of an antihypertensive drug. The excluded kidney donors were generally older compared with included donors (median age 57 years vs. 52 years) and more were women (65% vs. 56%). The kidney donors were matched to 11,030 individuals from the general population (Table 1). Alcohol-related disorders, filled prescriptions for lipid modifying agents and antidepressants were less common among kidney donors compared with the general population cohort (1.1% vs. 1.5%; 2.8% vs. 3.5%; 5.9% vs. 7.0%, respectively).

For comparison with blood donors, we identified 1,325 kidney donors and 448,549 blood donors. After application of the exclusion criteria a total of 1,007 kidney donors and 260,494 blood donors remained and were eligible for analysis (Table 2). The proportions and weighted proportions of alcohol-related disorders and use of lipid modifying agents and antidepressants were lower in blood donors compared with kidney donors.

Study Outcomes

The cumulative risks after 10 years of follow-up for kidney donors compared with the general population cohort were 15.6% versus 14.1% for hypertension, 2.1% versus 3.0% for AF, 4.5% versus 7.8% for MACE, and 2.4% versus 5.4% for all-cause mortality. The risk of hypertension was virtually similar between kidney donors and the general population cohort (HR, 1.11 [95% CI, 0.93–1.32]), while kidney donors had a decreased risk of AF (HR, 0.59 [95% CI, 0.38–0.94]) and MACE (HR, 0.68 [95% CI, 0.52–0.89]) as well as all-cause mortality (HR, 0.57 [95% CI, 0.40–0.80]) when compared with the general population cohort (Figure 2 and Table 3).

Figure 2.

Cumulative risks of outcomes. (A) Cumulative risk of initiating treatment for hypertension in kidney donors compared with the risk in the general population cohort. (B) Cumulative risk of AF, atrial fibrillation, or flutter in kidney donors compared with the risk in the general population cohort. (C) Cumulative risk of MACE, major adverse cardiovascular events (myocardial infarction, ischemic stroke, and all-cause mortality) in kidney donors compared with the risk in the general population cohort. (D) Cumulative all-cause mortality risk in kidney donors compared with the risk in the general population cohort

When comparing living kidney donors to blood donors the SIR for hypertension was 1.40 (95% CI, 1.17–1.66) suggesting that kidney donors had an increased risk of initiating treatment for hypertension when compared to blood donors. In contrast, the SIR for AF, MACE, and all-cause mortality was 0.88 (95% CI, 0.55–1.39), 1.17 (95% CI, 0.88–1.55), and 1.10 (95% CI, 0.75–1.61), respectively, indicating no difference in the incidence between kidney donors and blood donors (Table 4). The SIRs were similar when restricting the analysis to the period of 1996–2017 (data not shown).

Less than 3% of the observed CVD events in kidney donors were based exclusively on diagnoses from emergency room visits. In the sensitivity analysis including emergency room diagnoses as well when excluding cohort members with previous disease the HR remained unchanged for MACE and hypertension while changing from 0.59 (95% CI, 0.38–0.94) to 0.60 (95% CI, 0.38–0.94) for AF.

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