13-LB: Measured vs. Estimated GFR in Young Adults with Uncomplicated T1D

Background: eGFR equations are used to monitor progression of kidney disease, but their performance is incompletely understood in young adults with T1D and preserved GFR. To address this deficit, we compared two eGFR equations (creatinine-based CKD-EPI and modified Schwartz) to mGFR in this population. Methods: GFR based on plasma iohexol clearance was measured in 53 patients (24 males) with T1D, as part of the CAN-SOLVE CKD study Results: Mean age was 20.6±2.1 yrs with mean diabetes duration of 13.1±3.3 yrs. Mean HbA1c and ACR were 8.1±1.3 and 1.6±1.9 mg/mmol, respectively. Mean mGFR was 107.6±15.9 ml/min/1.73 m2. The Schwartz eGFR had a smaller mean bias (5.6 vs. 27.4 ml/min/1.73m2), better accuracy, and overall correlation compared to the CKD-EPI eGFR, while the latter had slightly superior precision. However, both equations were in poor agreement with mGFR. Examination of the Bland Altman plots reveals that, in the lower normal range, the CKD-EPI equation overestimated mGFR. The modified Schwartz equation showed no discernible tendencies. Conclusion: In young adults with T1D and preserved GFR, the modified Schwartz eGFR performed slightly better than CKD-EPI eGFR. Overall, however, both were in poor agreement with mGFR suggesting caution about the use of eGFR as a surrogate outcome in longitudinal studies and emphasizing the need to develop novel equations for this population. Disclosure K. Gaebe: None. C. A. White: None. F. H. Mahmud: Advisory Panel; Self; Insulet Corporation, Lilly Diabetes. J. W. Scholey: None. L. Motran: None. M. Palaganas: None. Y. T. Elia: None. D. Cherney: Other Relationship; Self; AbbVie Inc., AstraZeneca, Bayer AG, Boehringer Ingelheim International GmbH, Janssen Scientific Affairs, LLC., Lilly Diabetes, Merck & Co., Inc., Mitsubishi-Tanabe, Maze Inc, Prometic, Novo Nordisk, Sanofi. E. B. Sochett: None. Funding Canadian Institutes of Health Research (20R26070); JDRF