External Validation of the Kidney Failure Risk Equation and Re-Calibration with Addition of Ultrasound Parameters

Abstract

Background and objectives Progression of CKD toward ESRD is heterogeneous. The Kidney Failure Risk Equation (KFRE) was developed to identify CKD patients at high risk of ESRD. We aimed to externally validate KFRE and to test whether the addition of predefined Duplex ultrasound markers -renal resistive index (RRI) or difference of resistive indices in spleen and kidney (DI-RISK) -improved ESRD prediction.Design, setting, participants, & measurements The prospective Cardiovascular and Renal Outcome in CKD 2-4 Patients-The Fourth Homburg evaluation (CARE FOR HOMe) study recruits CKD stage G2-G4 patients referred to a tertiary referral center for nephrologic care. Four hundred three CARE FOR HOMe participants enrolled between 2008 and 2012 had available RRI measurements at study inclusion; they were subsequently followed for a mean of 4.461.6 years. This subcohort was used to validate KFRE and to assess the added value of the ultrasound markers (new models KFRE+RRI and KFRE+DI-RISK). Model performance was assessed by log-likelihood ratio test, c-statistic, integrated discrimination improvement metrics (for study participants without subsequent ESRD [IDI No ESRD ] and for patients with ESRD [IDI ESRD ]), and calibration plots. If either new model improved on KFRE, we determined to validate it in an independent cohort of 162 CKD patients.Results KFRE predicted ESRD in CARE FOR HOMe participants with a c-statistic of 0.91 (95% confidence interval, 0.83 to 0.99). Adding RRI improved the KFRE model (P,0.001), and the KFRE+RRI model was well calibrated; however, the c-statistic (0.91 [0.83-1.00]) was similar, and overall sensitivity (IDI No ESRD =0.05 [0.00-0.10]) or overall specificity (IDI ESRD =0.00 [0.00-0.01]) did not improve. Adding DI-RISK did not improve the KRFE model. In the external validation cohort, we confirmed that the KFRE+RRI model did not outperform KFRE.Conclusions Routine Duplex examinations among CKD patients did not improve risk prediction for progression to ESRD beyond a validated equation.

Arteriovenous Fistula Maturation in Prevalent Hemodialysis Patients in the United States: A National Study

“…Hence, 60% of US incident dialysis patients have only a catheter at initiation, while another 20% have a maturing AVF or AVG requiring a catheter at initiation. Furthermore, progression of chronic kidney disease (CKD) to ESRD requiring dialysis can be difficult to predict, 20, 21 thresholds for dialysis initiation vary, 22, 23 and patients may express reluctance toward access placement consistent with clinical expediency. 24 Timely vascular access planning and placement is thus fraught with multiple barriers.…”

Renal resistive index in hypertensive patients

“…The analysis also showed that, during a median follow-up of 2.2 years, RRI ≥ 0.70 was significantly associated with increased all-cause mortality. 38 There is the notion that as RRI is highly influenced by extrarenal factors such as cardiac function and systemic arterial compliance, with pulse pressure being the principal determinant, its prognostic value has been related to vascular disease that is often systemic. Of note, those with RRI ≥ 0.70 had lower eGFR compared to those with RRI < 0.70, but this relationship with eGFR was not seen in the multivariate analysis.…”

“…37 On the other hand, in a recent study, the routine Duplex examinations among stage 2-4 CKD patients did not improve risk prediction for progression to end-stage renal disease beyond a validated equation. 38 There is the notion that as RRI is highly influenced by extrarenal factors such as cardiac function and systemic arterial compliance, with pulse pressure being the principal determinant, its prognostic value has been related to vascular disease that is often systemic. 6 However, in a 7 years follow-up study of 726 Americans from the Cardiovascular Health Study Renal, Doppler signals from the renal parenchyma showed significant associations with subsequent CV events after controlling for other significant factors, such as renal function, HTN, diabetes and history of CV events.…”

Statistical Methods for Cohort Studies of CKD: Prediction Modeling

“…A PubMed search of prediction model yields over 40,000 papers. In CKD, research has focused on predicting CKD progression (1,2), cardiovascular events (3), and mortality (4-6) among many other outcomes (7). Interest in developing prediction models will continue to grow with the emerging focus on personalized medicine and the availability of large electronic databases of clinical information.…”