Tuesday, August 5, 2008

IAC: Jury Out on Heterosexual HIV Risk

By Michael Smith, North American Correspondent, MedPage Today

Published: August 04, 2008

Reviewed by Zalman S. Agus, MD; Emeritus Professor

University of Pennsylvania School of Medicine.

MEXICO CITY, Aug. 4 -- A popular estimate that only one in 1,000 heterosexual contacts with an HIV-positive partner results in infection flies in the face of the largely heterosexual HIV epidemic in Africa, a researcher said here.

A meta-analysis of 27 published articles on the topic showed a range of infection rates as high as one transmission for every 3.1 instances of anal intercourse, Kimberly Powers, M.S.P.H., a Ph.D. student at the University of North Carolina, said during a poster session at the International AIDS Conference.

"The take-away message is that there is no single estimate that pertains to every sexual contact" among heterosexuals, Powers said. Estimates of risk vary depending on a range of co-factors, such as the presence of genital ulcer disease or circumcision, she said.

Powers and colleagues, including senior author Myron Cohen, M.D., of the University of North Carolina, conducted a systematic review and meta-analysis -- published online in The Lancet Infectious Diseases -- of all published articles on heterosexual HIV infectivity up to April 27, 2008.

They found 27 articles reporting on 15 distinct populations, and analyzed the most precise estimates for the 15 groups.

Infectivity estimates were all over the map, the researchers found, with heterogeneity on a Cochran's Q test that was significant at P<0.0001.>
Action Points

Explain to interested patients that a popular estimate of the risk of HIV transmission through heterosexual sex is one infection for every 1,000 contacts.

Note that this meta-analysis found highly variable rates in the published literature, and argued that the one-in-a-thousand figure should be regarded as a lower boundary.

Primary source: The Lancet Infectious Diseases
Source reference:
Powers KA, et al "Rethinking the heterosexual infectivity of HIV-1: a systematic review and meta-analysis" Lancet Infectious Diseases 2008; DOI: 10.1016/S1473-3099(08)70156-7.

1 comment:

IRMA said...

Here is a nice summarizing news article


Hetero sex a big HIV risk
(in The Australian)

Adam Cresswell, Health editor | August 06, 2008

STRAIGHT couples are much more likely to transmit HIV during sex than most people realise, with new research showing the true risk may be hundreds of times higher than official guidelines suggest.

Doctors and patients are told that on average only one heterosexual transmission of the AIDS virus would be expected for every 1000 sexual contacts, assuming one partner was HIV-positive and the other negative.

But US researchers have told a world meeting of HIV experts in Mexico that the true figure could be as high as one transmission for every 10 instances of vaginal sex.

The risk could be as high as one transmission for every three instances of heterosexual anal sex, the researchers told the International AIDS Conference - a risk level more than 300 times greater than the 1:1000 figure would suggest.

The researchers, who analysed findings from 27 previous studies on HIV transmission, said the underestimate had arisen because most of the studies were based on heterosexual couples with particularly low-risk habits.

Risk factors that would be common among a more representative sample included the presence of genital ulcers or other sexually transmitted infections; having sex a short time after the HIV-positive partner had been infected; and the male partner being uncircumcised.

The findings were published online yesterday by The Lancet Infectious Diseases.

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