Table 1.

Cohort Sizes^*

Offer Rate	Acceptance Rate	HIV Prevalence	Cohort Size
5/day	55%	0.5%	4
5/day	80%	0.5%	6
5/day	55%	1.0%	8
5/day	80%	1.0%	11
5/day	55%	3.0%	22
5/day	80%	3.0%	32
5/day	55%	5.4%	39
5/day	80%	5.4%	57
10/day	55%	0.5%	8
10/day	80%	0.5%	11
10/day	55%	1.0%	15
10/day	80%	1.0%	21
10/day	55%	3.0%	43
10/day	80%	3.0%	63
10/day	55%	5.4%	78
10/day	80%	5.4%	113
Universal	55%	0.5%	11
Universal	80%	0.5%	16
Universal	55%	1.0%	21
Universal	80%	1.0%	31
Universal	55%	3.0%	63
Universal	80%	3.0%	91
Universal	55%	5.4%	113
Universal	80%	5.4%	164

HIV = human immunodeficiency virus.

^*Cohort size is dependent on four factors: the number of people visiting the Emergency Department annually, the percentage of patients offered testing, the percentage of patients accepting testing, and the prevalence of HIV. Due to uncertainty regarding the latter three rates, a variety of cohort sizes were modeled. Cohort size is calculated in the following manner: at an offer rate of 10 tests per business day, 2600 tests would be offered annually. If 55% of patients accept testing, 1430 tests would be conducted. At a 1% prevalence of disease, 14.3 patients would be identified as disease positive. Rounding up to the next whole person results in a cohort size of 15.