Abstract: FR-PO214
Accuracy of Glomerular Filtration Rate Estimates among Patients with Cancer
Session Information
- Onconephrology: Immunotherapy Nephrotoxicity and Assessment of GFR
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1700 Onconephrology
Authors
- Lees, Jennifer S., University of Glasgow, Glasgow, United Kingdom
- Fu, Edouard, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, Netherlands
- Faucon, Anne-Laure, Karolinska Institutet, Stockholm, Stockholm, Sweden
- Elyan, Benjamin Michael Peter, University of Glasgow, Glasgow, United Kingdom
- Inker, Lesley Ann, Tufts University School of Medicine, Boston, Massachusetts, United States
- Levey, Andrew S., Tufts University School of Medicine, Boston, Massachusetts, United States
- Mark, Patrick Barry, University of Glasgow, Glasgow, United Kingdom
- Carrero, Juan Jesus, Karolinska Institutet, Stockholm, Stockholm, Sweden
Background
Little is known about the accuracy of glomerular filtration rate (GFR) assessment among people with cancer. Most cancer guidelines and trials recommend estimated creatinine clearance (eClcr) using the Cockcroft-Gault (CG) equation. Accuracy is key to determine cancer prognosis, treatment eligibility and correct dosing of treatments with narrow therapeutic index.
Methods
We performed a cross-sectional study including 1,781 adults with incident cancer referred for 1,989 determinations of measured GFR (mGFR) using single-point plasma clearance of iohexol in Stockholm, Sweden, with concurrent measurements of creatinine and cystatin C. We assessed the performance of eClcr, estimated GFR based on creatinine (eGFRcr: CKD-EPI 2009/2021, EKFC 2021), cystatin C (eGFRcys: CKD-EPI 2012, EKFC 2023) and the combination (eGFRcr-cys: CKD-EPI 2012/2021, EKFC 2023) equations against mGFR. Values were non-indexed to body surface area and reported in mL/min. Accuracy was reported as % of patients with estimated values that differed by more than 30% of mGFR (1-P30). Bias was estimated as median (interquartile range; IQR) difference between mGFR and eCrcl or eGFR.
Results
Mean age was 64 (SD 14) years, 36% were female with mean mGFR 76 (SD 31) mL/min. The most common cancers were bladder (41%), lung (15%) and colorectal (13%); 13% had metastatic disease. 1-P30 was best for eGFRcr-cys (6-8%). eClcr (1-P30: 17%) had similar accuracy to eGFRcr (1-P30: 13-26%) and eGFRcys (1-P30: 12-17%). Accuracy varied by mGFR (Figure A). Median bias was lowest for eGFRcr-cys CKD-EPI 2012 (-0.5, IQR -6.2 to 6.4 mL/min) and highest for eGFRcr CKD-EPI 2021 (9.8, IQR 0.9 to 19.7 mL/min). Across mGFR categories, eGFRcr-cys equations were the least biased (Figure B).
Conclusion
Non-indexed eGFRcr-cys with CKD-EPI and EKFC equations provide the most accurate estimates of mGFR in patients with cancer, with potential to improve dosing and classification across treatment thresholds compared to eClcr and eGFRcr.