Estimating kidney function does the job in patients on cisplatin

In patients receiving cisplatin-based chemotherapy, estimated glomerular filtration rate (eGFR) is sufficient for the determination of kidney function, a recent study has shown.

The study included 121 patients (median age, 55 years; 27 percent female), from which kidney function data over 470 cisplatin cycles were collected. Paired eGFR and urinary creatinine clearance (uCrCl) measurements were obtained. The primary outcome of interest was the number of false negatives, defined as cycles with uCrCl <50 mL/min/1.73 m² but eGFR ≥50 mL/min/1.73 m².

The median eGFR and uCrCl values before initiation of cisplatin treatment were 94 and 102 mL/min/1.73 m², respectively.

Eight out of the 470 cycles saw false negatives, yielding a final rate of 1.7 percent (95 percent confidence interval [CI], 0.5–2.9; p=0.004). In all eight instances of false negatives, the uCrCl was lower than the eGFR (mean, 43 v 112 mL/min/1.73 m²; mean difference, 65 mL/min/1.73 m²; p<0.0001). Notably, none of the eight false negatives led to a delay in chemotherapy.

Linear mixed models showed that overall, uCrCl measurements were significantly higher than eGFR estimates (mean difference, 13.0 mL/min/1.73 m²; p<0.0001). Both measures were in adequate agreement in most cases, though researchers still documented outlying uCrCl values. The resulting overall agreement was thus relatively low, with an intraclass coefficient of 0.72.

Nevertheless, the researchers said that using eGFR as a strategy to measure kidney function (and omitting direct GFR measurement using uCrCl) is acceptable in patients with solid cancers receiving cisplatin chemotherapy.