- The Canadian Medical Association Journal has issued a
special alert to doctors warning that patients who tested negative for
HIV may in fact be infected with the virus.
Authorities advised Health Canada of the risk in April, after problems
with the sensitivity of two popular rapid screening kits for the human
immunodeficiency virus were identified at British Columbia's Centre for
Disease Control (BCCDC).
The tests involve a finger prick for a drop of blood and typically yield
results within 20 minutes.
The manufacturer, BioChem ImmunoSystems Inc., agreed to stop selling the
products and Health Canada sent a letter to health care professionals who
perform HIV testing advising them to track down affected patients for further
examination. At least one man who originally received a negative result
has since tested positive for the AIDS virus.
But not all of the patients who may have received false negative results
have surfaced. At Toronto's Hassle Free Clinic, Canada's busiest anonymous
HIV testing site, only 21% of the 1,900 patients potentially at risk have
Health Canada and the manufacturer could have done much more to publicize
the risk of false negative results, said Jane Greer, the clinic's director.
"Health Canada and BioChem really didn't do much of an advertising
campaign," she said. "I felt it was left to us."
The clinic issued its own news advisory and bought $7,000 worth of newspaper
advertising to alert its transient clientele of the risk.
The lack of patients willing to be retested is doubly worrying because
new research probing the kits' accuracy has revealed they were less reliable
than the BCCDC had feared.
For one part of their evaluation, staff at the agency used the kits on
63 HIV-positive patients at St. Paul's Hospital in Vancouver. The kits
missed the virus at least seven times.
"The HIV tests we use routinely in labs now have nearly 100% sensitivity
-- in other words, they might miss one person in many thousands,"
said Darrel Cook, laboratory manager at the BCCDC.
"We don't think anything less than 99.9% sensitive is acceptable."
The research and the advisory will appear in the Canadian Medical Association
Journal later this month.
The alert is already posted on the journal's Web site as a precaution.
Health Canada should have sent its warning letter to all physicians, not
just a select group, said Dr. John Hoey, the journal's editor-in-chief.
"Health Canada couldn't tell us how many of these test kits had been
distributed nor where they had gone," he said.
"So we phoned the company. The company also had no way of tracking
who had these kits.... We thought it was important for us as the medical
journal that most physicians get to at least put it in our pages and let
them know quickly that there really is a problem."
More than 14,000 of the Fast-Check HIV test kits have been sold in Canada
since they were licensed in March, 2000.
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