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24 février 2011 

Frequent testing for HIV results in better prognosis for those who do get HIV

Texte en anglais
par: Micheal Carter
Source: http://www.aidsmap.com/
Image: www.aids-info.ch
test.jpg Frequent testing for HIV is associated with improved outcomes after diagnosis, Dutch investigators report in the online edition of AIDS. People who tested regularly for HIV but subsequently contracted the infection had half the risk of death when compared to people diagnosed at their first HIV test, the researchers found.

Patients who tested for HIV at least annually had higher CD4 cell counts at the time HIV therapy was started and lower mortality rates compared to individuals who tested for HIV less frequently. The worst outcomes were seen in patients who were diagnosed at their first HIV test, and a high proportion of these individuals already had a CD4 cell count below 200 cells/mm3 at the time of diagnosis.

"Patients repeatedly tested for HIV antibodies...had higher CD4 cell counts at cART [combination antiretroviral therapy] initiation and a lower rate compared to those initially tested positive," comment the authors.

Thanks to antiretroviral therapy, many HIV-positive individuals can look forward to a long and healthy life.

However, even with HIV therapy mortality rates are still higher among HIV-positive individuals than the general population, and this is largely because many people have their HIV diagnosed late.

Guidelines in the Netherlands and many other countries recommend that individuals at high risk of HIV, such as gay men, should test for HIV at least annually.

"Although seemingly obvious, it has never before been demonstrated that patients who were repeatedly tested for HIV before testing positive have a better clinical prognosis than patients who initially tested positive," write the investigators.

They therefore designed a study involving 5494 patients who were newly diagnosed with HIV in the Netherlands between 2004 and 2008.

On the basis of their HIV testing history prior to diagnosis, these patients were divided into three groups:

Never previously tested - HIV-positive at first test.

Infrequently tested - last negative test between twelve and 24 months before positive result.

Frequently tested - tested HIV-negative less than a year before repeat tests and positive diagnosis.

The investigators then conducted analyses to see if frequency of testing was associated with two outcomes:

CD4 cell count at the time HIV treatment was started.

Mortality rates

The vast majority of patients were diagnosed with HIV at their first HIV test (4067 individuals vs 561 infrequent testers vs 866 frequent testers)

There were important demographic differences between these three groups, most notably, 23% of individuals diagnosed at their first test were sub-Saharan Africans, but just 4% of those diagnosed with HIV after frequent screening came from this group.

The median CD4 cell count at the time of diagnosis was associated with testing history, and was lowest for those whose HIV was diagnosed at a first test (350 cells/mm3 vs 470 cells/mm3 for infrequent testers, and 550 cells/mm3 for patients who tested frequently).

Frequency of testing was also associated with the presence of an AIDS diagnosis at the time of diagnosis (16% first test vs 2% infrequent testing vs 3% frequent testing).

Overall, 186 patients died. The mortality rate was highest for patients diagnosed at a first HIV test (1.33 per 100 person years), and was significantly lower for individuals who had tested previously (infrequent test = 0.58 per 100 person years, p = 0.02; frequent testing = 0.54 per 100 person years, p = 0.003).

After taking into consideration differences in baseline characteristics, the investigators calculated that individuals with a history of HIV testing had a 50% reduction in their risk of death compared to patients whose HIV was detected the first time they had an HIV test.

Median CD4 cell count at the time HIV therapy was started was 190 cells/mm3 among patients diagnosed the first time they had an HIV test, compared to 250 cells/mm3 (difference, p < 0.0007) for patients with a history of infrequent testing, and 260 cells/mm3 (difference, p < 0.0007) for patients who tested for HIV at least once a year.

Patients diagnosed the first time they had an HIV test were also the group most likely to have an AIDS diagnosis and CD4 cell count below 200 cells/mm3 at the time antiretroviral therapy was initiated.

"Our findings illustrate the benefit of repeated testing for HIV," write the investigators, "it shortens the time between infection and diagnosis and improves the likelihood of timely treatment, with the prevention of clinical progression to AIDS and death."

The researchers also believe that "increasing testing to annually may greatly impact on transmission rates at a population level." They quote a modelling study that suggested that transmission rates in the Netherlands could be reduced by 40% over a decade "if the average time between infection and diagnosis was reduced to 1 year."


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