Abstract
BackgroundThere is emerging evidence that the 4-variable Kidney Failure Risk Equation (KFRE) can be used for risk prediction of graft failure in transplant recipients. However, geographical validation of the 4-variable KFRE in transplant patients is lacking, as is whether the more extensive 8-variable KFRE improves predictive accuracy. This study aimed to validate the 4- and 8-variable KFRE predictions of the 5-year death-censored risk of graft failure in patients in the United Kingdom.MethodsA retrospective cohort study involved 415 transplant recipients who had their first renal transplant between 2003 and 2015 and were under follow-up at Salford Royal NHS Foundation Trust. The KFRE risk scores were calculated on variables taken 1-year post-transplant. The area under the receiver operating characteristic curves (AUC) and calibration plots were evaluated to determine discrimination and calibration of the 4- and 8-variable KFREs in the whole cohort as well as in a subgroup analysis of living and deceased donor recipients and in patients with an eGFR< 45 ml/min/1.73m2.ResultsThere were 16 graft failure events (4%) in the whole cohort. The 4- and 8-variable KFREs showed good discrimination with AUC of 0.743 (95% confidence interval [CI] 0.610–0.876) and 0.751 (95% CI 0.629–0.872) respectively. In patients with an eGFR< 45 ml/min/1.73m2, the 8-variable KFRE had good discrimination with an AUC of 0.785 (95% CI 0.558–0.982) but the 4-variable provided excellent discrimination in this group with an AUC of 0.817 (0.646–0.988). Calibration plots however showed poor calibration with risk scores tending to underestimate risk of graft failure in low-risk patients and overestimate risk in high-risk patients, which was seen in the primary and subgroup analyses.ConclusionsDespite adequate discrimination, the 4- and 8-variable KFREs are imprecise in predicting graft failure in transplant recipients using data 1-year post-transplant. Larger, international studies involving diverse patient populations should be considered to corroborate these findings.
Highlights
There is emerging evidence that the 4-variable Kidney Failure Risk Equation (KFRE) can be used for risk prediction of graft failure in transplant recipients
This analysis found that the 2- and 5-year risk of graft failure estimated by the 4-variable KFRE can provide adequate risk prediction, but the investigators raised concerns that the risk calculation was imprecise if it was undertaken using data within 2-years post-transplantation
Tangri et al [6] showed that the pooled C-statistic increased to 0.83 (0.74–0.91) when the KFRE was applied to transplant patients with an estimated glomerular filtration rate (eGFR)< 45 ml/ min/1.73m2, and this excellent discrimination is reproduced in our cohort with an area under the curve (AUC) of 0.817 for the 4-variable KFRE
Summary
There is emerging evidence that the 4-variable Kidney Failure Risk Equation (KFRE) can be used for risk prediction of graft failure in transplant recipients. The Kidney Failure Risk Equation (KFRE) is the most extensively validated risk prediction tool for estimating the 2- and 5-year risk of ESRD in patients with chronic kidney disease (CKD) stages 3–5 [4] The validation of this tool in transplant recipients has been undertaken in 3 studies to date. Validation of the 4-variable KFRE has been undertaken in a post-hoc analysis of the Folic Acid for Vascular Outcomes Reduction in Transplantation trial (FAVORIT) and comprised 2889 patients from cohorts in North America and one from Brazil [7] This analysis found that the 2- and 5-year risk of graft failure estimated by the 4-variable KFRE can provide adequate risk prediction, but the investigators raised concerns that the risk calculation was imprecise if it was undertaken using data within 2-years post-transplantation
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