Pop quiz can predict STIs in women (but not men)

A pop-quiz developed to assess a person’s risk of sexually transmitted infection has proven accurate for women, but not so for men.

A study by Johns Hopkins Medicine involved offering the quiz to people interested in home-testing kits, which have been available in Maryland and Washington DC since 2004.

The findings, published this week in the journal Sexually Transmitted Infections, suggest those considered high-risk by their quiz results are in fact more likely to be infected, but only among female respondents.

The findings also suggest women are twice as likely to have an STI than men.

The questionnaire, known as the Risk Quiz, evaluates risk of infection based on six “yes or no” questions, relating to the respondent’s age, number of sexual partners and condom use. Each question is weighted differently, according to how much it impacts the likelihood of infection. Men who score 7+, and women who score 8+, are considered “high-risk”.

The quiz was taken by 3,200 people, each of whom also received a home-testing kit, containing a swab which can be used and shipped to the lab free of charge, to test for chlamydia, gonorrhoea and trichomoniasis.

Overall, 14% of women tested positive to at least one infection, versus 7% for men, suggesting women are twice as likely to have an STI.

Among the quiz respondents, women who scored in the “high-risk” category were four times more likely to have an STI than those in lower categories. However, among men, quiz results did not correspond to actual infection rates.

Lead researcher Charlotte Gaydos, a professor of medicine at the Johns Hopkins University School of Medicine, says this could reflect a lack of honesty among male respondents, or simply a difference in infection rates.

“We are not quite sure why this is, but untruthfulness or the fact that men tend to have lower rates of STIs are possibilities,” says Gaydos.

Gaydos also emphasises that concrete statistical information is tricky to determine, because the quiz and the home-testing are both voluntary. Regardless, experts hope the quiz will help physicians identify high-risk patients, in order to encourage more frequent testing.

“We test a lot of people who are not infected, and although a tool like this might not predict every single case, we think it can be helpful in rapidly predicting the likelihood of an STI for physicians and patients,” she says.

In the US, an estimated 19 million STIs are diagnosed every year, and the Centres for Disease Control and Prevention recommends women under 25 get tested annually for chlamydia and gonorrhoea.