From the Journals

Opt-out HIV testing in EDs can help identify undiagnosed cases



Results of a new study indicate that opt-out HIV testing, in particular “notional consent testing” where a patient is not asked or counseled before conducting the test, is an effective tool for identifying undiagnosed HIV cases in populations with an HIV positivity rate greater than 0.2%.

On implementation of opt-out testing of patients aged 18-59 years admitted to the ED at St. George’s University Hospital in London, the proportion of tests performed increased from 57.9% to 69%. Upon increasing the age range to those 16 and older and implementing notional consent, overall testing coverage improved to 74.2%.

“An opt-out HIV testing program in the emergency department provides an excellent opportunity to diagnose patients who do not perceive themselves to be at risk or who have never tested before,” lead author Rebecca Marchant, MBBS, of St. George’s Hospital, said in an interview.

The study was published online in HIV Medicine.

She continued, “I think this take-away message would be applicable to other countries with prevalence of HIV greater than 2 per 1,000 people, as routine HIV testing in areas of high prevalence removes the need to target testing of specific populations, potentially preventing stigmatization.”

Despite excellent uptake of HIV testing in antenatal and sexual health services, 6% of people living in the United Kingdom are unaware of their status, and up to 42% of people living with HIV are diagnosed at a late stage of infection. Because blood is routinely drawn in EDs, it’s an excellent opportunity for increased testing. Late-stage diagnosis carries an increased risk of developing an AIDS-related illness, a sevenfold increase in risk for death in the first year after diagnosis, and increased rates of HIV transmission and health care costs.

The study was conducted in a region of London that has an HIV prevalence of 5.4 cases per 1,000 residents aged 15-59 years. Opt-out HIV testing was implemented in February 2019 for people aged 18-59, and in March 2021, this was changed to include those aged 16-plus years along with a move to notional consent.

Out of 78,333 HIV tests, there were 1054 reactive results. Of these, 728 (69%) were known people living with HIV, 8 (0.8%) were not contactable, 2 (0.2%) retested elsewhere and 3 (0.3%) declined a retest. A total of 259 false positives were determined by follow-up testing.

Of those who received a confirmed HIV diagnosis, 50 (4.8%) were newly diagnosed. HIV was suspected in only 22% of these people, and 48% had never previously tested for the virus. New diagnoses were 80% male with a median age of 42 years. CD4 counts varied widely (3 cells/mcL to 1,344 cells/mcL), with 60% diagnosed at a late stage (CD4 < 350 cells/mcL) and 40% with advanced immunosuppression (CD4 < 200 cells/mcL).

“It did not surprise me that heterosexuals made up 62% of all new diagnoses,” Dr. Marchant noted. “This is because routine opt-out testing in the ED offers the opportunity to test people who don’t perceive themselves to be at risk or who have never tested before, and I believe heterosexual people are more likely to fit into those categories. In London, new HIV diagnoses amongst men who have sex with men have fallen year on year likely due to pre-exposure prophylaxis being more readily available and a generally good awareness of HIV and testing amongst MSM.”

Michael D. Levine, MD, associate professor of emergency medicine at the University of California, Los Angeles, agreed with its main findings.

“Doing widespread screening of patients in the emergency department is a feasible option,” Dr. Levine, who was not involved with this study, said in an interview. “But it only makes sense to do this in a population with some prevalence of HIV. With some forms of testing, like rapid HIV tests, you only get a presumptive positive and you then have a confirmatory test. The presumptive positives do have false positives associated with them. So if you’re in a population with very few cases of HIV, and you have a significant number of false positives, that’s going to be problematic. It’s going to add a tremendous amount of stress to the patient.”

A version of this article first appeared on

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