US experts recommend routine HIV screening

Key US experts have supported a move to routine HIV screening in health-care settings – a decision backed by recent study results and published policy recommendations. Experts now agree that routine HIV testing (with an ‘opt-out’ for patients who do not wish to be tested) could ultimately prove cost-effective, and improve the health outcomes of hundreds of thousands of HIV-positive Americans who are unaware of their status.

Recommendations for routine testing

At a meeting held in Washington on November 29 and 30, Opportunities for Improving HIV Diagnosis, Prevention and Access to Care in the U.S., nearly 300 doctors, officials and advocates gathered to discuss new approaches to HIV testing and prevention. The consensus at the meeting was to support recent recommendations from the US Centers for Disease Control (CDC), published in the Morbidity and Mortality Weekly Report in September (Branson 2006). Main points of the new recommendations are as follows:

• In all health-care settings, patients aged 13 – 64 years should be screened for HIV.
• Exceptions should be made only if prevalence of undiagnosed HIV infection has been shown to be under 0.1% (i.e., if less than 1 person in 1000 is HIV-positive but undiagnosed) in that setting.
• Everyone seeking treatment for tuberculosis or sexually transmitted diseases should be screened for HIV.
• People at high risk should be screened at least annually.
• Separate written consent should not be required; patients should be given the choice to decline (opt out) but informed that they will be tested unless they do choose to opt out.
• In areas with high rates of HIV infection among pregnant women, pregnant women who test HIV-negative should be screened again in the third trimester.

HIV in the United States

The US has one of the highest HIV rates among industrialised countries.

Current estimates are as follows:

• Total US population: 290 million.
• Approximately 40,000 new HIV infections are reported each year.
• In 2002, 38% to 44% of all adults had been tested for HIV.
• Estimated HIV-positive US residents: 1.0 million to 1.2 million (just under 0.4% of the total population).
• An estimated quarter of these – over 250,000 – are undiagnosed and unaware of their HIV status.
• Up to 45% of positive test results occur so late that the person develops AIDS within a year of diagnosis.

Until now, HIV testing has not been routinely conducted in medical-care settings, but mostly aimed at “at-risk” populations. Because of the stress and stigma that go with diagnosis, HIV testing is handled quite differently than most other infections, with an emphasis on patient consent, anonymity, and pre- and post-test counseling.

Computer simulation confirms effectiveness

In the December 5^th issue of the Annals of Internal Medicine, a research team led by A. David Paltiel published a study which used computer simulation to model the cost-effectiveness of routine HIV testing. They concluded that routine, one-time rapid testing is cost-effective in settings where at least 0.2% of the population is HIV-positive and undiagnosed. However, an editorial by the CDC’s Bernard M Branson MD (lead author of the new CDC recommendations) states that routine screening is actually “likely to be more cost-effective than Paltiel and colleagues suggest.”

Paltiel’s study used mathematical models to simulate the outcomes of HIV testing for various levels of prevalence rates (how many people are HIV-positive), undiagnosed prevalence, and incidence (new infection rates). Analysis then compared the costs of testing (including pre-and post-test counselling) to the costs of health care (including drug and hospital costs) – both for infected individuals, and for people subsequently infected by them. The full analysis explored the effects of many different variables. The bottom line was that “the benefits of routine HIV testing in all adults in the United States outweigh the likely harms.”

Cost analysis was based on the cost of a “quality-adjusted life year [QALY]” – essentially, how much it costs the system to add one year of “perfect health” to one patient’s life. The “conventional premise” is that “interventions that produce a QALY for $50,000 or less are a bargain.” The Paltiel study found that adding a single rapid HIV test for each patient cost $37,100 per QALY gained – well within the usual definition of cost-effectiveness.

As noted, the CDC recommendations now call for routine screening wherever the undiagnosed prevalence is thought to be more than 0.1%. Paltiel’s team notes that their study “arrived at a slightly higher … estimate … (0.2%) but entirely supports the shift from targeted screening based on patient risk factors to routine screening based on prevalence and incidence thresholds.” While the team acknowledged the practical difficulties of measuring these thresholds, Branson’s editorial notes that the “prevalence of undiagnosed HIV infection is likely to fall within [the] range for cost-effective screening in most practice settings.”

Consent, anonymity and counselling

A shift to routine testing has serious implications for the impact on the patient. Regarding consent, Branson notes that opt-out screening “is designed to make HIV screening more practical for both physicians and their patients. Patients are free to decline the test without recrimination, and they do not need to admit to some past indiscretion to qualify for testing.” Noting that pre-test counselling costs three times as much as the rapid test itself, he concedes that “physicians are more likely to conduct screening than counseling”.

Regarding confidentiality, the CDC states that “HIV test results should be documented in the patient's confidential medical record and should be readily available to all health-care providers involved in the patient's clinical management.” Beyond acknowledging the special case of consent and confidentiality for adolescents, there is little further discussion – a lack that should be addressed as policies are developed.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, commented: “making testing a routine part of medical care is clearly the thing to do, so long as we make sure to accompany that with care, treatment and counselling.”