Remaining kidney volume indexed to weight as a strong predictor of estimated glomerular filtration rate at 1 year and mid-term renal function after living-donor nephrectomy - a retrospective observational study

Association of the Calcification Score of the Abdominal Aorta, Common Iliac, and Renal Arteries with Outcomes in Living Kidney Donors

BACKGROUND

Vascular calcification is an ever-more-common finding in protocoled pre-transplant imaging in living kidney donors. We intended to explore whether a connection could be found between the Agatston calcification score, prior to kidney donation, and post-donation renal function.

METHODS

This is a retrospective analysis of 156 living kidney donors who underwent living donor nephrectomy between January 2010 and December 2016. We quantified the total calcification score (TCaScore) by calculating the Agatston score for each vessel, abdominal aorta, common iliac, and renal arteries. Donors were placed into two different groups based on their TCaScore: <100 TCaScore group and ≥100 TCaScore group. The relationship between TCaScore, 1-year eGFR, proteinuria, and risk of 1 measurement of decreased renal function (eGFR < 60 mL/min/1.73 m²) over 5 years of follow-up was investigated.

RESULTS

The ≥100 TCaScore group consisted of 29 (19%) donors, with a median (interquartile range) calcification score of 164 (117-358). This group was significantly older, 56.7 ± 6.9 vs. 45.5 ± 10.6 (p < 0.001), had a higher average BMI (p < 0.019), and had a lower preoperative eGFR (p < 0.014). The 1-year eGFR was similarly diminished, 69.9 ± 15.7 vs. 76.3 ± 15.5 (p < 0.048), while also having an increased risk of decreased renal function during the follow-up, 22% vs. 48% (p < 0.007).

CONCLUSIONS

Our study, through univariate analyses, found a relationship between a TCaScore > 100, lower 1-year eGFR, and decreased renal function in 5 years. However, a higher-than-expected vascular calcification should not be an excluding factor in donors, although they may require closer monitoring during follow-up.

CT volumetry performs better than nuclear renography in predicting estimated renal function one year after living donation

The evaluation of split renal function (SRF) is a critical issue in living kidney donations and can be evaluated using nuclear renography (NR) or computerized tomography (CT), with unclear comparative advantages. We conducted this retrospective study in 193 donors to examine the correlation of SRF assessed by NR and CT volumetry and compared their ability to predict remaining donor renal function at 1 year, through multiple approaches. A weak correlation between imaging techniques for evaluating the percentage of the remaining kidney volume was found in the global cohort, with an R2 = 0.15. However, the Bland-Altman plot showed an acceptable agreement (95% of the difference between techniques falling within - 8.51 to 6.11%). The predicted and observed eGFR one year after donation were calculated using the CKD-EPI, and CG/BSA equations. CT volume showed a better correlation than NR for both formulas (adjusted R2 of 0.42. and 0.61 vs 0.37 and 0.61 for CKD-EPI and CG/ BSA equations, respectively). In non-nested modeling tests, CT volumetry was significantly superior to NR for both equations. CT volumetry performed better than NR in predicting the estimated renal function of living donors at 1-year, independently from the eGFR equation.

Is Compensation Prediction Score Valid for Contralateral Kidney After Living-Donor Nephrectomy in the United States?

BACKGROUND

Compensation after living donor nephrectomy is well known, and a compensation prediction score (CPS) was made in Japan previously. The aim of this study was to perform external validation of CPS in the United States.

METHODS

We studied retrospectively 78 living donor nephrectomies in our institution. We defined a favorable compensation as a postdonation estimated glomerular filtration rate (eGFR) at 1 year of >60% of the predonation eGFR. We analyzed the living donors' clinical characteristics and outcomes and validated CPS score.

RESULTS

The median (range) donor age was 43 (21-63) years, and median body mass index was 26.9 (18.3-35.9) kg/m². Forty-four percent of donors were White. The donor predonation eGFR was 105 (61-134) mL/min/1.73 m², and the postdonation eGFR at 1 year was 73.2 (0-115) mL/min/1.73 m². Eighty-three percent of donors had a favorable compensation. The CPS was 9.6 (1.6-15.6) and showed strong diagnostic accuracy for predicting favorable compensation (area under the curve, 0.788; 95% confidence interval, 0.652-0.924; P = .001). The CPS showed a significant positive correlation with the postdonation eGFR at 1 year (R = 0.54; P < .001).

CONCLUSIONS

In the United States, the CPS would be a valid tool with which to predict a favorable compensation of remnant kidney function.