Removal of body surface area normalisation improves raw‐measured glomerular filtration rate estimation by the Chronic Kidney Disease Epidemiology Collaboration equation and drug dosing in the obese

Background/Aim We aimed to compared estimated glomerular filtration rate ( eGFR ) according to the C hronic K idney D isease E pidemiology C ollaboration equation ( CKD‐EPI ), with (mL/min/1.73 m 2 ) and without body surface area ( BSA ) normalisation ( CKD‐EPI _no BSA , m L /min) against measured 99m Technetium ‐ diethylenepentaacetic acid ( T c‐ DTPA GFR ) (m L /min) in 222 individuals, including 80 with malignancy. Methods BSA was calculated for each individual using the D u B ois equation. The CKD ‐ EPI and CKD ‐ EPI _no BSA equations were compared with measured T c‐ DTPA GFR with respect to bias, proportion within 30% of GFR ( P 30) and root mean square error for predicting levels of GFR , and concordance in relation to carboplatin dosing. Results The mean ( SD ) for BSA and measured GFR for the entire group was 1.99 (0.25) m 2 and 127 (41) mL/min respectively. The P 30 for T c‐ DTPA GFR was significantly higher with the CKD‐EPI _no BSA (80%) than with the CKD‐EPI equation (63%, P = 0.0001). In those with body mass index ( BMI ) > 30 kg/m 2 , the P 30 values for the CKD ‐ EPI _no BSA and CKD ‐ EPI were 74% and 42% respectively ( P < 0.0001). Carboplatin dosing concordance for the cancer patients using the CKD ‐ EPI and CKD‐EPI _no BSA equation was 71% and 56% respectively ( P = 0.07). In 78 individuals with BMI > 30 kg/m 2 , concordance in relation to carboplatin dosing using CKD ‐ EPI _no BSA was 65% compared with 26% with the CKD‐EPI ( P < 0.0001). Conclusion The CKD‐EPI without normalisation ( CKD‐EPI _no BSA ) equation was superior to the CKD‐EPI equation in estimating raw‐measured T c‐ DTPA GFR (mL/min).