Purpose: In 2006, the Centers for Disease Control and Prevention (CDC) recommended routine HIV screening in all US health care settings using an opt-out strategy in which patients are told an HIV test will be performed, unless they decline, without separate written informed consent for HIV testing. To address concerns by public health practitioners, we assessed the cost and effects of rapid and conventional testing under 3 scenarios: (1) sexually transmitted disease (STD) clinic opt-in testing, in which patients give written consent for testing, and receive traditional pre-test prevention counseling; (2) STD) clinic opt-out testing, in which pre-test prevention counseling is not required for HIV testing, and (3) emergency department (ED) opt-out testing, in which no pre-test prevention counseling is provided.

Methods: Using a decision model, we calculated the incremental cost per HIV-infected patient who received correct test results under each scenario for conventional and rapid testing. Cost and effectiveness data were derived from CDC demonstration projects, national wage data, and published literature. The analysis was conducted from the provider perspective.

Results: Table. Incremental Cost per HIV-Infected Client Receiving Test Results (2004, USD)

Type of HIV Test (HIV prevalence = .01)	STD clinic, Opt-in	STD clinic, Opt-out	Emergency, Opt-out
Conventional	$3,596	$1,946	$1,102
Rapid	$2,076	$2,076	$1,747

The incremental cost of providing test results to HIV-infected patients using either type of HIV test was lower in the ER than the STD settings. Rapid testing was less cost effective in both opt-out scenarios because, without prevention counseling, test kits are a larger proportion of total testing costs and rapid test kits are more expensive. Threshold costs for rapid test kits (basecase = $9.00) below which rapid testing becomes more cost effective than conventional testing were $8.29 (STD-Opt Out) and $4.81 (ED). Results were also sensitive to the return rate of HIV-infected persons after a conventional test, and HIV prevalence.

Conclusions: HIV testing in emergency departments with an HIV prevalence of at least 1% may be more cost effective than HIV testing in STD clinics. Rapid testing is currently less cost effective than conventional testing under the opt-out scenarios, unless costs for rapid test kits drop below the cost assumed in this analysis.