Table 2.

Cost reduction by using biomarkers as enrollment criteria to predict clinical acute kidney injury

Enrollment criteria			Sample size details		Trial screening		Total trial cost (screening + trial)a
Clinical risk factorsb	Known insultc	Kidney injury biomarker	AKI event rate control arm	Required sample size (RR 0.7)	$500/patient screening cost		$10,000/patient trial costd		$45,000/patient trial coste
					Screen failure rate	Screening cost (in dollars)	Total cost (in millions)	% Cost reductionf	Total cost (in millions)	% Cost reductionf
✓	—	—	4.3%	6902	0%	$3451	$69.0	Reference	$314.0	Reference
✓	✓	—	6.9%	4211	63%	$5691	$47.8	34%	$195.2	38%
✓	—	pNGAL > 200 ng/ml	6.1%	4810	56%	$5466	$53.6	26%	$221.9	29%
✓	✓	pNGAL > 200 ng/ml	9.1%	3155	78%	$7171	$38.7	47%	$149.2	53%
✓	—	uIL-18 > 60 pg/ml	10.4%	2720	80%	$6800	$34.0	53%	$129.2	59%
✓	✓	uIL-18 > 60 pg/ml	12.2%	2294	88%	$9559	$32.5	55%	$112.8	64%

AKI, acute kidney injury; AKI event, doubling of serum creatinine or requiring dialysis; pNGAL, plasma neutrophil gelatinase–associated lipocalin; RR, relative risk; uIL-18, urinary interleukin-18.

^aExpressed in millions.

^bTRIBE-AKI cohort (high risk for AKI based on clinical risk factors; see Materials and Methods for details).

^cCardiopulmonary bypass time >120 minutes.

^dCost estimated assuming lower cost of $10,000 per patient, which may be more appropriate for a short-duration AKI therapeutic trial.

^eCost estimated based on $45,000 per patient. This cost is estimated based on recently reported pharmaceutical-sponsored trials in cardiology and endocrinology (from Roy²¹).

^fPercentage reduction in cost is calculated using trial with clinical risk factors as reference.