Validation of a Hypertension Risk Calculator for Living Kidney Donors

E. S. Helgeson¹, S. Vempati¹, E. F. Palzer¹, G. Mjøen², A. J. Haugen³, A. Matas⁴

¹Division of Biostatistics, University of Minnesota, Minneapolis, MN, ²Department of Transplant Medicine, Oslo University Hospital, Oslo, Norway, ³Department of Internal Medicine, Bærum Hospital, Sandvika, Norway, ⁴Department of Surgery, University of Minnesota, Minneapolis, MN

Meeting: 2022 American Transplant Congress

Abstract number: 98

Keywords: Hypertension, Kidney, Living donor

Topic: Clinical Science » Kidney » 39 - Kidney Living Donor: Long Term Outcomes

Session Information

Session Name: Kidney Living Donor: Long Term Outcomes

Session Type: Rapid Fire Oral Abstract

Date: Sunday, June 5, 2022

Session Time: 5:30pm-7:00pm

Presentation Time: 6:00pm-6:10pm

Location: Hynes Room 206

*Purpose: It would be ideal if candidates considering kidney donation understood their long-term risks. Using single-center data (n=4055; median [IQR] f/u: 18 [9-28] yrs), we developed a calculator for post-donation HTN and validated it using long-term f/u data from an external single-center cohort (n=1189, median [IQR] f/u: 9 [5-17] yrs).

*Methods: Variables considered, assessed at donation, included: age, sex, race, relationship to recipient, family history of HTN, BMI, serum glucose, eGFR, systolic and diastolic BP, smoking status, creatinine, recipient with HTN, decade of donation, hyperlipidemia alone, and hyperlipidemia or total cholesterol ≥240 mg/dL. Four modeling approaches were evaluated: two Cox proportional hazards models and two random forest models, each with one modeling development of HTN alone and one with death as a competing risk. 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 c-index and net reclassification improvement.

*Results: In the development cohort, 34% reported HTN with a median (IQR) of 16 (8-24) yrs post-donation; in the validation cohort, 29% after 17 (10-22) yrs post-donation. The most accurate model was the Cox-proportional hazards model with age, sex, race, eGFR, systolic and diastolic BP, BMI, glucose, smoking history, family history of HTN, relationship to recipient, and hyperlipidemia (C statistic, 0.72 in the development cohort and 0.82 in the validation cohort).

Table 1: Performance of top models. Pooled results across imputed datasets. Model 1 included age, sex, race, eGFR, systolic and diastolic BP, BMI, glucose, smoking history, family history of HTN, relationship to recipient, and hyperlipidemia. Model 2 replaced hyperlipidemia with hyperlipidemia or total cholesterol ≥240.


	Model 1	Model 2
Performance in development cohort
C-index (sd)	0.72 (0.001)	0.72 (0.001)
Performance in validation cohort^*
C-index (95% CI)	0.82 (0.79, 0.84)	0.81 (0.79, 0.84)
NRI (95% CI) compared to model with age alone	0.58 (0.45, 0.70)^**	0.67 (0.54, 0.80)

*Family history of HTN set to 0 in for validation cohort **Hyperlipidemia set to 0 in validation cohort

*Conclusions: A post-donation HTN calculator was developed and validated; it provides kidney donor candidates a long-term projection of HTN risk to better inform decision making.

To cite this abstract in AMA style:

Helgeson ES, Vempati S, Palzer EF, Mjøen G, Haugen AJ, Matas A. Validation of a Hypertension Risk Calculator for Living Kidney Donors [abstract]. Am J Transplant. 2022; 22 (suppl 3). https://atcmeetingabstracts.com/abstract/validation-of-a-hypertension-risk-calculator-for-living-kidney-donors/. Accessed November 23, 2024.

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