# Compare carboplatin dosed by BSA-adjusted CKD-EPI eGFR with Cockcroft-Gault on toxicity and response

Source: https://onco.cc/ideas/idea-upgrade-carboplatin-gfr-estimate-outcome-study/  
OnCo record `idea-upgrade-carboplatin-gfr-estimate-outcome-study` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Carboplatin doses depend on an estimate of kidney function. The 2025 international guideline (ADDIKD) recommends a newer estimate (BSA-adjusted CKD-EPI) over the old Cockcroft-Gault formula when kidney function cannot be measured directly, because it is more accurate. No study has yet shown that switching changes side effects or how well treatment works.

## Summary

The recommendation. ADDIKD (2025) recommends BSA-adjusted eGFR CKD-EPI as an alternative to measured GFR in the Calvert formula, on clinical consensus with a strong recommendation, and calls the switch away from creatinine clearance a significant practice change, given the long reliance on creatinine clearance calculated by the Cockcroft-Gault equation. It notes that many prescribing software packages use creatinine clearance by default.

The evidence. In 2,471 patients at Cambridge, BSA-adjusted CKD-EPI was the most accurate published estimate against measured GFR, and Cockcroft-Gault gave a dose more than 20% off in 25.5% of patients against 18.6% (Janowitz 2017, abstract). These are dose-accuracy outcomes; ADDIKD's own outstanding questions add that cystatin C-based equations may be more accurate where eGFR is unreliable.

## Fields

- Kind: Idea
- Last checked: 2026-11-11
- Tags: protocol-upgrade; upgrade:promising; evidence:moderate
- Hypothesis: Carboplatin dosed with BSA-adjusted CKD-EPI eGFR produces fewer grade 3 or 4 thrombocytopenias and dose delays than dosing with Cockcroft-Gault, with no loss of response.
- Rationale: A guideline-driven change to the dose of one of the most used cytotoxics should be followed by a measure of what it does to patients, not only to the arithmetic.
- Proposed test: A before-and-after or stepped-wedge study across centres adopting ADDIKD, or a randomised comparison within a trial network, recording platelet nadirs, dose delays and reductions, and response, with measured GFR in a subset to calibrate.
- Maturity: early-clinical
- Actor: research

## Sources

- Sandhu et al., Aligning kidney function assessment in patients with cancer to global practices in internal medicine (ADDIKD Part 1, eClinicalMedicine 2025): https://doi.org/10.1016/j.eclinm.2025.103102
- Sandhu et al., Integrating International Consensus Guidelines for Anticancer Drug Dosing in Kidney Dysfunction (ADDIKD) into everyday practice (eClinicalMedicine 2025): https://doi.org/10.1016/j.eclinm.2025.103161
- Janowitz et al., New Model for Estimating Glomerular Filtration Rate in Patients With Cancer (J Clin Oncol 2017; abstract read): https://doi.org/10.1200/JCO.2017.72.7578

## Connected records

- fronts: [Chemotherapy](https://onco.cc/fronts/chemotherapy/)
- technologies: [Carboplatin dosing by kidney function: the Calvert formula and how kidney function is measured](https://onco.cc/technologies/carboplatin-calvert-dosing/)
- drugs: [Carboplatin](https://onco.cc/drugs/carboplatin/)
- bottlenecks: [Wrong doses](https://onco.cc/bottlenecks/b-dose-optimisation/)
- protocols: [Carboplatin dose calculation by the Calvert formula and kidney function](https://onco.cc/protocols/carboplatin-dose-calculation/)

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