Open Access

ARTICLE

Creatinine‐based estimation of glomerular filtration rate in patients with a Fontan circulation

Thomas G. Wilson^1,2, Yves d’Udekem^1,2,3, David S. Winlaw^4,5, Rachael L. Cordina^5,6, Julian Ayer^4,5, Thomas L. Gentles⁷, Robert G. Weintraub^1,2,8, Leeanne E. Grigg⁹, Michael Cheung^1,8, Timothy M. Cain¹⁰, Padma Rao¹⁰, Charlotte Verrall⁴, Karin Du Plessis¹, Kathryn Rice⁷, Ajay J. Iyengar^1,3

1 Heart Research Group, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
2 Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
3 Department of Cardiac Surgery, The Royal Children’s Hospital, Melbourne, Victoria, Australia
4 The Heart Centre for Children, The Children’s Hospital at Westmead, Sydney, New South Wales, Australia
5 Department of Paediatrics, University of Sydney, Sydney, New South Wales, Australia
6 Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
7 Greenlane Paediatric and Congenital Cardiac Service, Starship Children’s Hospital, Auckland, New Zealand
8 Department of Cardiology, The Royal Children’s Hospital, Melbourne, Victoria, Australia
9 Department of Cardiology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
10 Medical Imaging Department, The Royal Children’s Hospital, Melbourne, Victoria, Australia

* Corresponding Author: Yves d’Udekem, Department of Cardiac Surgery, Royal Children’s Hospital, Flemington Rd, Parkville, VIC 3052, Australia. Email:

Congenital Heart Disease 2019, 14(3), 454-463. https://doi.org/10.1111/chd.12746

Abstract

Background: Patients with a Fontan circulation are at risk of renal dysfunction. We analyzed cross‐sectional data in pediatric and adult Fontan patients in order to assess the accuracy of commonly used serum creatinine‐based methods in estimating glo‐ merular filtration rate (GFR). Methods: A total of 124 Fontan patients (58 children, 66 adults) were enrolled across three study centers. Measurement of GFR (mGFR) using in vivo ^99mTc‐DTPA clear‐ ance was performed. Various serum creatinine‐based equations were used to calcu‐ late estimated GFR (eGFR). Results: Mean mGFR was 108 ± 28 mL/min/1.73 m² in children and 92 ± 20 mL/ min/1.73 m² in adults. Fourteen children (25%) and 28 adults (45%) had an mGFR <90 mL/min/1.73 m² . There was no significant correlation between mGFR and eGFR (Schwartz) in children (r = 0.22, P = .1), which substantially overestimated mGFR (bias 50.8, 95%CI: 41.1‐60.5 mL/min/1.73 m² , P < .0001). The Bedside Schwartz equation also performed poorly in the children (r = 0.08, P = .5; bias 5.9, 95%CI: −2.9‐14.6 mL/ min/1.73 m² , P < .0001). There was a strong correlation between mGFR and both eGFR (CKD‐EPI) and eGFR (MDRD) in adults (r = 0.67, P < .0001 in both cases), how‐ ever, both methods overestimated mGFR (eGFR(CKD‐EPI):bias 23.8, 95%CI: 20‐27.6 mL/min/1.73 m² , P < .0001; eGFR (MDRD):bias 16.1, 95%CI: 11.8‐20.4 mL/ min/1.73 m² , P < .0001). None of the children with an mGFR <90 mL/min/1.73 m² had an eGFR (Schwartz) <90 mL/min/1.73 m² . Sensitivity and specificity of eGFR (CKD‐EPI) and eGFR (MDRD) for mGFR <90 mL/min/1.73 m² in adults were 25% and 92% and 39% and 100%, respectively. Conclusions: This study identifies the unreliability of using creatinine‐based equa‐ tions to estimate GFR in children with a Fontan circulation. The accuracy of formulas incorporating cystatin C should be further investigated and may aid noninvasive sur‐ veillance of renal function in this population.

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