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Study shows MDs, health workers misinformed about probability of contracting sexually transmitted infections

Published: 28 November 2005

McGill research shows lack of understanding about HIV and chlamydia risks

A new study published by researchers at McGill University reveals that many of Canada's doctors and sexual health workers are significantly misinformed about the transmission rates for two serious STIs.

In a survey, 1,901 doctors and STI clinic workers across Canada responded to questions asking them to state the probability of HIV or chlamydia transmission during one encounter of unprotected vaginal intercourse. Only 1.4% knew that the probability was below 0.5% for HIV. Barely five percent of the respondents knew that the rate of transmission for chlamydia was between 30 and 40 percent.

"The fact that only a small percent [of the health care profession] seem to know actual transmission rates suggests that such information is currently not part of the curriculum in medical school, or is not emphasized," says Bärbel Knäuper, professor of psychology at McGill, and one of the authors of the study.

According to the study, these findings suggest a difficult ethical dilemma for policy makers. On the one hand, health care providers have an obligation to provide honest and accurate information to patients. Doctors and workers who better understand the relatively low transmission rate of HIV could potentially calm a patient concerned about a broken condom or other episode of unprotected sex. On the other hand, promoting this information could result in increased complacency towards very serious diseases.

One thousand six hundred sixty-five general and specialized physicians responded to the researchers' survey, which was sent anonymously to doctors across Canada. In addition, the questionnaire that tested knowledge of HIV and chlamydia was also completed by 236 employees and volunteers from STI clinics.

Workers in STI clinics were especially likely to overstate the probability of transmitting HIV. A significant number replied that the likelihood of transmission after one encounter of vaginal intercourse was fifty percent, with some suggesting a one hundred percent rate of transmission.

The results of the study were published in the October issue of Sexually Transmitted Diseases, a scholarly journal that publishes peer-reviewed articles on medical and sociological topics related to STIs.

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