Impact of the 2021 CKD-EPI equation on anticancer pharmacotherapy in black and non-black cancer patients

Cancer and kidney disease disproportionately impact Black patients. The CKD-EPI₂₀₂₁ equation was developed to estimate glomerular filtration rate (eGFR) without using race. We assessed the impact of using CKD-EPI₂₀₂₁ instead of CKD-EPI₂₀₀₉ or Cockcroft-Gault (CG) on dosing and eligibility of anticancer drugs in Black and non-Black patients. Utilizing the National Cancer Institute Theradex database, deindexed eGFR (mL/min) was calculated for 3931 patients (8.6 % Black) using CKD-EPI₂₀₂₁, CKD-EPI₂₀₀₉, and CG. Dosing simulations based on each eGFR were performed for ten anticancer drugs with kidney function-based eligibility or dosing cutoffs. eGFR differences using CKD-EPI₂₀₂₁ versus CKD-EPI₂₀₀₉ varied between Black and non-Black patients (p < 0.001); on average, Black patients had 10.3 mL/min lower eGFR and non-Black patients had 4.2 mL/min higher eGFR using CKD-EPI₂₀₂₁. This corresponded to a difference in relative odds of cisplatin ineligibility using CKD-EPI₂₀₂₁ versus CKD-EPI₂₀₀₉; Black patients had 48 % higher odds of ineligibility and non-Black patients had 27 % lower odds of ineligibility using CKD-EPI₂₀₂₁ (p < 0.001). When using CKD-EPI₂₀₂₁ versus CG, eGFR differences were similar between Black and non-Black patients (p = 0.679) and relative difference in odds of cisplatin ineligibility did not vary. Using CKD-EPI₂₀₂₁ versus CKD-EPI₂₀₀₉ differentially impacts Black versus non-Black cancer patients; Black patients have lower calculated eGFR and are less likely to receive full doses of drug using CKD-EPI₂₀₂₁. From the historical default of CG, adopting CKD-EPI₂₀₂₁ would not disparately impact patients based on race, but would result in Black patients being less likely to receive full doses of drug than if CKD-EPI₂₀₀₉ were used.