Mathematical Model Shows Opt-out HIV Testing Would Save Lives

		SUMMARY: Switching from "opt-in" to "opt-out" HIV screening -- so that people are tested as part of routine medical care unless they explicitly decline -- could result in improved survival, with as many as 750,000 years of life saved, according to an analysis presented last weekend at the 47th Annual Meeting of the Infectious Diseases Society of America (IDSA 2009) in Philadelphia.

By Liz Highleyman

In the early years of the HIV/AIDS epidemic, the level of stigma and discrimination was such that advocates successfully demanded informed consent requirements for HIV testing in the U.S. that are much more stringent that those for other diseases. Typically providers had to obtain specific written consent and take extra measures to ensure confidentiality (for example, recording results separate from regular medical records).

One drawback of such policies is that epidemiologists have had difficulty accurately estimating the prevalence (total cases) and incidence (new cases) of HIV infection. Another is that many people are not diagnosed until they begin experiencing symptoms of serious immune system decline, resulting in late initiation of antiretroviral therapy (ART).

To address these problems, the Centers for Diseases Control and Prevention (CDC) recommended in 2006 that health-care facilities should switch to routine, opt-out HIV testing. "HIV screening is recommended for patients in all health-care settings after the patient is notified that testing will be performed unless the patient declines," according to the revised guidelines. "Separate written consent for HIV testing should not be required; general consent for medical care should be considered sufficient to encompass consent for HIV testing."

Some states, however, have continued to require opt-in testing. Michael April from Harvard Medical School and colleagues aimed to quantify the decrease in survival attributable to reduced testing associated with opt-in state consent laws.

The researchers examined the difference in 2006 HIV testing rates between states with opt-in versus opt-out consent laws. They systematically reviewed state statutes to categorize states according to type of consent law, and then used state and national HIV surveillance reports to calculate and compare 2006 testing rates between categories.

Next, the investigators applied these different testing rates to a mathematical model to estimate how much life was lost in opt-out states. The model initially assumed a 0.09% prevalence of undiagnosed infection, a 0.02% annual HIV incidence rate, and treatment efficacy based on studies of ART. In sensitivity analyses, they varied estimates of undiagnosed prevalence, incidence, and how much the testing rate increased due to opt-out screening. They also considered scenarios in which opt-out consent discouraged segments of the population from testing (for example, due to concerns about their HIV status being revealed).

Results

	In 2006, the probability of diagnosis of HIV positive individuals was 19.9% in opt-in states compared with 24.9% in opt-out states -- a difference of 25% attributable to opt-out consent.
	In the initial scenario, the mean lifespan of people with HIV was 792.1 months in opt-in states versus 801.2 months in opt-out states.
	Nationwide implementation of opt-out testing was estimated to produce 549,437 life years saved over the lifetime of the current HIV positive population.
	When the assumed increase in testing associated with opt-out consent was cut in half, to 12.5%, national opt-out testing was estimated to yield 348,210 life years saved.
	When the assumed increase in testing was raised to 37.5%, opt-out testing yielded 744,540 life years saved.
	To cancel out the gains attributable to opt-out testing in the initial scenario, 25.4% of the population would have to decrease their rate of testing by half, or 10.4% would need to cease all testing in response to opt-out consent.

"Reduced HIV testing due to opt-in consent is associated with a significant loss of life," the researchers concluded. "[R]evision of state laws in accordance with CDC recommendations could yield 549,437 life years saved."

Harvard Medical School, Boston, MA; Massachusetts General Hospital, Boston, MA; Yale School of Medicine, New Haven, CT.

11/6/09

Reference
MD April, RP Walensky, J Chiosi, and others. The Survival Cost of Opt-In Consent for HIV Testing. 47th Annual Meeting of the Infectious Diseases Society of America (IDSA 2009). Philadelphia, PA. October 29-November 1, 2009. Abstract 1254.