Development and Validation of a Hypertension Risk Calculator for Living Kidney Donors.

BACKGROUND: Ideally, when deciding whether to donate, kidney donor candidates would understand their long-term risks. Using single-center data (N = 4055; median [quartiles] follow-up: 18 [9-28] y), we developed a calculator for postdonation hypertension and validated it using long-term data from an external single-center cohort (N = 1189, median [quartiles] follow-up: 9 [5-17] y). METHODS: Risk factors considered were routinely obtained at evaluation from donor candidates. Two modeling approaches were evaluated: Cox proportional hazards and random survival forest models. Cross-validation prediction error and Harrell's concordance-index were used to compare accuracy for model development. Top-performing models were assessed in the validation cohort using the concordance-index and net reclassification improvement. RESULTS: In the development cohort, 34% reported hypertension at a median (quartiles) of 16 (8-24) y postdonation; and in the validation cohort, 29% reported hypertension after 17 (10-22) y postdonation. The most accurate model was a Cox proportional hazards model with age, sex, race, estimated glomerular filtration rate, systolic and diastolic blood pressure, body mass index, glucose, smoking history, family history of hypertension, relationship with recipient, and hyperlipidemia (concordance-index, 0.72 in the development cohort and 0.82 in the validation cohort). CONCLUSIONS: A postdonation hypertension calculator was developed and validated; it provides kidney donor candidates, their family, and care team a long-term projection of hypertension risk that can be incorporated into the informed consent process.

Increased risk of ischaemic heart disease after kidney donation.

BACKGROUND: Previous reports suggest increased risk of hypertension and cardiovascular mortality after kidney donation. In this study we investigate the occurrence of ischaemic heart disease and cerebrovascular disease, diabetes and cancer in live kidney donors compared with healthy controls eligible for donation. METHODS: Different diagnoses were assessed in 1029 kidney donors and 16 084 controls. The diagnoses at follow-up were self-reported for the controls and registered by a physician for the donors. Stratified logistic regression was used to estimate associations with various disease outcomes, adjusted for gender, age at follow-up, smoking at baseline, body mass index at baseline, systolic blood pressure at baseline and time since the donation. RESULTS: The mean observation time was 11.3 years [standard deviation (SD) 8.1] for donors versus 16.4 years (SD 5.7) for controls. The age at follow-up was 56.1 years (SD 12.4) in donors versus 53.5 years (SD 11.1) in controls and 44% of donors were males versus 39.3% in the controls. At follow-up, 35 (3.5%) of the donors had been diagnosed with ischaemic heart disease versus 267 (1.7%) of the controls. The adjusted odds ratio for ischaemic heart disease was 1.64 (confidence interval 1.10-2.43; P = 0.01) in donors compared with controls. There were no significant differences for the risks of cerebrovascular disease, diabetes or cancer. CONCLUSIONS: During long-term follow-up of kidney donors, we found an increased risk of ischaemic heart disease compared with healthy controls. This information may be important in the follow-up and selection process of living kidney donors.

Endothelial Dysfunction and 6-Year Risk of Mortality in Kidney Transplant Recipients.

BACKGROUND: Endothelial dysfunction is an early and potentially reversible stage in the atherosclerotic process. We assessed endothelial dysfunction noninvasively in kidney transplant recipients (KTRs) and evaluated the association with mortality and graft outcomes. METHODS: Flow-mediated dilation (FMD) was measured in arteria brachialis by ultrasound, with baseline diameters obtained at rest and maximal diameters obtained during reactive hyperemia occurring after 5 min of forearm occlusion. FMD% is the percentage difference of flow-mediated dilation relative to baseline. Endpoints on mortality and graft outcomes were collected from The Norwegian Renal Registry. The distribution of risk according to FMD levels was assessed in Cox regression using a restricted cubic spline function. FMD was dichotomized using receiver operating characteristic analysis to identify optimal cut points at maximal sensitivity and specificity. RESULTS: From a total of 269 KTRs in 2012, 152 (56.5%) were eligible and examined 10 wk after transplantation, and 145 had successful FMD measurements. During a mean follow-up of 6.5 y, 26 patients died, 11 lost their graft, and 34 experienced either graft loss or death. Mortality increased with lower FMD levels until about 5% dilation and did not change with further reduction in FMD% (P for nonlinearity <0.01). An optimal cut point of FMD ≤5.36% defined impaired endothelial function and FMD% below this level, was associated with fatal outcome, hazard ratio (HR), 9.80 (1.29-74.62), P = 0.03, uncensored graft loss, HR, 7.80 (1.83-33.30), P = 0.01, but an association with death-censored graft loss was lost after adjusting for pulse pressure, HR, 4.58 (0.55-37.92), P = 0.16. CONCLUSIONS: We found that impaired FMD is strongly associated with mortality in KTRs.

Living donation - any news on the donor?

PURPOSE OF REVIEW: Living kidney donation has been an established practice for many years. Although studies from the past decade have uncovered risks to the donor, living kidney donation is still promoted. In this review, the most recent studies are summarized. RECENT FINDINGS: Retrospective studies with long follow-up have detected an increased risk of hypertension among donors. Donors with hypertension at the time of donation may be at increased risk of adverse outcomes, but results differ. Recent studies have not found increased long-term mortality, but follow-up is short and control groups are of different quality. SUMMARY: In all, the most recent findings more or less corroborate previous knowledge in the field of living donation. There is still a need for new studies on mortality with appropriate control groups and long enough follow-up.

Increased long-term risk for hypertension in kidney donors - a retrospective cohort study.

Kidney donors may be at increased risk of end-stage renal disease and premature mortality. Elevated blood pressure after donation may contribute to the increased risks. In this cohort study, we have assessed long-term risk for the development of hypertension in kidney donors compared to a control group potentially eligible as donors. Follow-up data were obtained from previous living kidney donors. A healthy control group with baseline assessment from similar time periods as the donor nephrectomies was selected. Hypertension was defined as blood pressure >140/90, use of blood pressure medication, or established diagnosis of hypertension. Stratified logistic regression was used to estimate risk of hypertension at follow-up, adjusted for systolic blood pressure at baseline, age at follow-up, time since donation/baseline, gender, smoking at baseline, and BMI at baseline. A total of 368 donors (36%) had hypertension at follow-up, and 241 of these (23%) were using blood pressure medication. In adjusted stratified logistic regression analyses, odds ratio for hypertension was significantly increased (1.25, 95% confidence interval 1.12-1.39, P < 0.001) in donors compared with controls. Kidney donors appear to be at increased long-term risk for hypertension compared with healthy controls. This finding supports regular follow-up of blood pressure in kidney donors.

Long-term risk for kidney donors with hypertension at donation - a retrospective cohort study.

In the general population, small increases in blood pressure are associated with increased mortality. In kidney donors this association is less certain. We therefore assessed long-term overall and cardiovascular mortality in donors who were hypertensive at the time of donation compared with normotensive donors. Hypertension was defined as blood pressure >140/90 mmHg or use of antihypertensive drugs. Adequate records available in 2131 donors revealed that 140 were hypertensive and 1991 were normotensive. Multivariable regression analyses were performed for overall and cardiovascular mortality. Hypertensive donors were significantly older (mean 57.7 vs. 46.9 years), more were males (44.3% vs. 41.5%), had higher body mass index (26.4 vs. 24.7) and lower estimated glomerular filtration rate (91.8 vs. 101.2 ml/min/1.73 m2 ). After a median observation time of 20.8 years (interquartile range 11) 71 hypertensive donors had died and 26 of the deaths were cardiovascular. Multivariable analysis did not suggest a generalizable association between hypertension and long-term overall mortality [hazard ratio (HR) 1.1, 95% confidence interval (CI) 0.9-1.5, P = 0.34] or cardiovascular mortality (HR 1.1, 95% CI 0.7-1.8, P = 0.55). These data may support the use of older healthy kidney donors with hypertension at donation.