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HIV results while you wait

But instant test not without potential pitfalls

LIMITED USE: Dr Michael Rekart of the BCCDC sees a role for point of care instant HIV tests but isn't quite prepared to endorse them for general use. Credit: John Inch photo

For more than a year, Richmond-based bioLytical Laboratories has been producing and distributing the INSTI HIV-1 Rapid Antibody Test. It’s the only point of care HIV test currently licenced for use in Canada.

Unlike the typical HIV test that requires drawing a tube of blood, sending it for laboratory analysis and waiting for a week or more for the results, the INSTI test needs only a few drops of blood, can be conducted in a doctor’s office, and can return results in 60 seconds.

“This is not a home test,” cautions Dr Michael Rekart. “This is for health care clinics and is to be used by health care workers.” Rekart is director of sexually transmitted disease and HIV/AIDS control at the British Columbia Centre for Disease Control (BCCDC).

Like the standard test for HIV, called an enzyme-linked immunosorbent assay (ELISA), INSTI does not detect the virus itself. Rather it detects the presence of antibodies produced by the immune system in response to HIV infection. But it can take up to six months for HIV antibodies to reach detectable levels in the bloodstream after HIV gets into the body.

Richard Galli, chief science officer at bioLytical says the INSTI test represents an advancement in HIV detection and hopes to see it widely adopted by health care professionals.

“As many as 25 to 30 percent of individuals who are living with HIV and AIDS don’t know it,” he says. “That may indicate that there are some barriers to testing. Whatever the reason, there is an element of the population not coming forward.”

Although Rekart does see uses for the INSTI test, he views it as a specialized product rather than something that should be widely used.

“I don’t believe that HIV tests are inaccessible in our province, but I do see specific instances [where they might be helpful],” he says.

“One is when you need an immediate result and can’t wait for the regular testing systems. When pregnant women come to the emergency room in labour and haven’t had any screening, for example, the decision needs to be made whether to give them and their babies prophylaxis.” Prophylaxis, in this context, is a drug regime that can prevent an HIV-positive woman from passing the virus to her child during childbirth.

“A second use would be in people who wouldn’t go through the standard testing system,” continues Rekart. “This might be people who are marginalized, whose lives are so chaotic that it’s difficult for them to come back for results and follow-up, or for people who live in areas so remote from larger centres that they can’t get a standard test.

“Quite a large percentage of patients who get the standard HIV test don’t actually come back for the result,” he adds. “About 10 percent of positive tests don’t come back, and we can’t find the patients.”

Why not make the INSTI test the standard if instant results mean an end to the sometimes white-knuckle wait so many gay men experience between test and result?

“For tests that come out negative, the INSTI test is as accurate as the provincial laboratory, however there are more false positives,” explains Rekart.

A false positive is when a test returns a positive result for the presence of HIV antibodies in a blood sample when, in fact, the blood is free of HIV. Because of the false positives, Rykert says every positive result returned by INSTI needs to be confirmed with standard testing at the provincial laboratory.

BioLytical Laboratories did work with the BCCDC on the development of the INSTI test.

“They came to us to do the clinical trials because of our volume of patients at risk,” Rekart explains. “The accuracy of the test was quite high. They have been after us to endorse the test and use it in our clinics as a way of enhancing its credibility, but we’ve always held back because of the lack of quality control.

“There is currently no third-party independent quality assurance for this test,” he continues. “The only group that’s making sure that it’s accurate, batch after batch, is the company that makes it. That’s a conflict. We have had problems with that kind of non-independent quality control in the past.”

Another HIV point of care test was licenced for use in Canada in 2000. Produced by Montreal-based BioChem Immunosystems and called Fast Check, the test kits were recalled in 2002 and the licence revoked because of research done by the BCCDC.

“There were situations in which that test yielded a negative result but the person was actually infected,” says Rekart. “We knew this because the provincial laboratory was using Fast Check as a third check on its standard system.

“We informed Health Canada, the company, and ran a small evaluation of this test using people known to be positive from the intravenous clinic at St Paul’s Hospital,” he remembers. “A certain percentage of them were negative according to Fast Check, so the test had to be recalled.

“It’s our understanding that after Health Canada approval, manufacture of the test was subcontracted to a cheaper producer,” he explains. “This might have been the reason why it wasn’t as accurate as it seemed during initial trials.

“The problems were related to the sensitivity of the Fast Check test and the potential for some individuals to have received false negative results,” confirms Carole Saindon a spokesperson for Health Canada in Ottawa. “The manufacturer agreed to stop sale and recall the affected lots until the problem was identified and resolved. We initiated an investigation and follow-up to determine the cause of the problems. The medical device licence was suspended in 2004.”

What if a person were to test positive on a rapid test but then refuse to follow-up with a confirmatory test?

“If that happens, and the test is a false positive, that’s a tragedy for the patient,” says Rekart.

“As well-meaning as the company may be, they’re not in the right position to evaluate their own test,” he emphasizes. “We’re trying to correct that situation by doing quality assurance at the BCCDC on lots, but we’re not there yet.

“There’s a place for this test. It’s already approved. Any physician or health care provider can go out and buy it,” he continues. “We have two areas of responsibility; quality control on the lab side, and helping people learn to do the test properly. Even though we don’t endorse it, we produce guidelines to train people to do it properly because it’s a reality in British Columbia.”

The accuracy of test results over time isn’t the only reason Rekart hasn’t endorsed the INSTI test. Additionally, he notes the costs. “It’s not paid for by the Medical Services Plan,” he says. “The patient will have to pay for it, and the health care worker or clinic would probably pass along administrative and staff expenses.”

Galli acknowledges that having the INSTI test covered by provincial health care programs is a goal. “There may be other mechanisms for cost recovery,” he says. “Our goal as a company is to find the one that fits best in each province. The last choice would be a patient pay scenario. I don’t think anybody wants to see that.”

“I hope that people won’t look at the rapid test as a panacea,” Rekart concludes. “This isn’t the answer to accessibility for health care. If the standard test isn’t accessible, then there’s something else wrong that should be corrected.”