This estimates kidney function using a different formula than eGFR, historically used to guide medication dose adjustments — including some antibiotics used to treat pneumonia and other respiratory infections.
They were developed for different purposes and use different inputs. Cockcroft-Gault uses actual body weight and is useful for drug dosing; eGFR/CKD-EPI is more standardized for general kidney-function staging, so both remain in use depending on context.
Classically actual body weight, but for dosing many references use ideal body weight in normal-weight patients and adjusted body weight in obesity to avoid overestimating clearance.
Kidney function guides dose adjustments for medications — including some antibiotics used to treat pneumonia and other respiratory infections.
CrCl = [(140 − age) × weight (kg) × (0.85 if female)] ÷ (72 × serum creatinine).