Table 2. BioPET analysis of a biomarker with area under the receiver operating characteristic curve =0.92.

The clinical event occurs in 20% of patients without intervention. A trial of an intervention to help prevent the clinical event is designed to have 90% power to detect a 30% relative reduction in the event rate using one-sided hypothesis testing and α=0.025. The cost of screening is $1000 and the per patient trial cost is $10,000. The Screening Threshold is the proportion of patients who will be screened out of the trial. The Event Rate is the rate of the clinical event in the enriched study population not receiving the intervention. The Sample Size is the trial sample size calculated as a function of the event rate and statistical testing specifications. Total Screened is the total number of patients who would need to be screened to enroll the trial, which depends on the sample size and stringency of screening. Total Cost summarizes patient-related costs of different levels of enrichment, specifically the costs of biomarker-based screening and the costs of having a patient in a trial. The results here are also shown in Figure 1.

Screening Threshold	Event Rate	Sample Size	Total Screened	Total Cost	Percent Reduction in Total Cost
0%	0.20	1640	1640	16398000	Ref
5%	0.21	1541	1622	17034789	−3.9%
10%	0.22	1443	1603	16034949	2.2%
15%	0.24	1346	1583	15041843	8.3%
20%	0.25	1250	1562	14059403	14.3%
25%	0.27	1155	1539	13084639	20.2%
30%	0.28	1060	1514	12109590	26.2%
35%	0.30	966	1487	11149298	32%
40%	0.33	875	1458	10204768	37.8%
45%	0.35	784	1426	9266357	43.5%
50%	0.38	695	1391	8344788	49.1%
55%	0.42	608	1352	7435845	54.7%
60%	0.46	524	1310	6548590	60.1%
65%	0.51	443	1264	5689500	65.3%
70%	0.56	364	1213	4850961	70.4%
75%	0.63	289	1157	4049439	75.3%
80%	0.71	221	1104	3313108	79.8%
85%	0.79	162	1077	2693387	83.6%
90%	0.87	113	1130	2260041	86.2%
95%	0.95	77	1550	2324983	85.8%