Pre-Transplant Calcimimetic Use and Dose Information Improves the Accuracy of Prediction of Tertiary Hyperparathyroidism after Kidney Transplantation: A Retrospective Cohort Study

Abstract

Tertiary hyperparathyroidism (THPT) is characterized by elevated parathyroid hormone and serum calcium levels after kidney transplantation (KTx). To ascertain whether pre-transplant calcimimetic use and dose information would improve THPT prediction accuracy, this retrospective cohort study evaluated patients who underwent KTx between 2010 and 2022. The primary outcome was the development of clinically relevant THPT. Logistic regression analysis was used to evaluate pre-transplant calcimimetic use as a determinant of THPT development. Participants were categorized into four groups according to calcimimetic dose, developing two THPT prediction models (with or without calcimimetic information). Continuous net reclassification improvement (CNRI) and integrated discrimination improvement (IDI) were calculated to assess ability to reclassify the degree of THPT risk by adding pre-transplant calcimimetic information. Of the 554 patients, 87 (15.7%) developed THPT, whereas 139 (25.1%) received pre-transplant calcimimetic treatment. Multivariate logistic regression analysis revealed that pre-transplant calcimimetic use was significantly associated with THPT development. Pre-transplant calcimimetic information significantly improved the predicted probability accuracy of THPT (CNRI and IDI were 0.91 [p < 0.001], and 0.09 [p < 0.001], respectively). The THPT prediction model including pre-transplant calcimimetic information as a predictive factor can contribute to the prevention and early treatment of THPT in the era of calcimimetics.

Keywords: calcimimetics; kidney transplantation; parathyroidectomy; prediction model; tertiary hyperparathyroidism.

FIGURE 1

Participant selection flowchart. eGFR, estimated glomerular filtration rate; KTx, kidney transplantation; PTx, parathyroidectomy; THPT, tertiary hyperparathyroidism.

FIGURE 2

Scatter plots of the predicted probabilities of Model 1 and Model 2. The circles represent non-THPT cases, and the triangles represent THPT cases. The black dashed line represents the coordinates where the predictions of Model 1 and Model 2 match. The circles below the black dashed line or the triangles above it indicate that the THPT predictions have improved in Model 2 compared with Model 1. THPT, tertiary hyperparathyroidism.

FIGURE 3

ROC curves for the prediction of THPT from Model 1 and Model 2. The gray curve is the ROC curve for Model 1, and the black dashed curve is the ROC curve for Model 2. The ROC AUCs and 95% CIs are shown. AUC, area under the curve; 95% CI, 95% confidence interval; ROC, receiver operating characteristic; THPT, tertiary hyperparathyroidism.

FIGURE 4

Calibration diagrams for THPT prediction models using the bootstrap method. The blue and red dashed lines represent the calibration diagrams for Model 1 and Model 2, respectively. THPT, tertiary hyperparathyroidism.