Are You at Risk for Sexually Transmitted Infections?

If you’re having sex, you’re at risk for sexually transmitted infections. But what are the chances you’ll actually get one?

A quick sex quiz from researchers at the Johns Hopkins School of Medicine will give you a better idea. It asks your age along with five questions about your love life, and clinical trials show it works pretty well — particularly for women, not quite as well for men. Answers are weighted, but it’s the kind of test you don’t want to ace: the higher your score, the higher your risk for an infection. Whether you use condoms and how many sex partners you have are critical factors in determining risk.

“Adolescents don’t want to tell their parents they’re sexually active,” said Charlotte Gaydos, a developer of the quiz and a professor in the division of infectious diseases in the Johns Hopkins School of Medicine. Nor can teenagers easily get tested for sexually transmitted infections without a parent knowing. “If they don’t have a way to get to a hospital or clinic — they don’t have cars, they don’t have credit cards — how can they pay and keep it private from their parents?”

With support from the National Institutes of Health, she and her colleagues started a website at IWantThe Kit.org that provides free S.T.I. test kits to residents of Maryland and Washington, D.C., and the quiz is posted on the site. “The pop quiz can help them realize, ‘Oh my gosh, maybe I should order a kit, I got a high score.’”

In a recent study, Dr. Gaydos and her colleagues looked at 836 women and 558 men in their early 20s who had taken the quiz. They had also all gotten tests for sexually transmitted infections through IWantThekit.org, which provides free home collection test kits that include directions for taking vaginal, penile or rectal swabs. Visitors then send back the tissue samples for free testing. If results are positive, the website directs patients to clinics that offer free or low-cost treatment.

The vast majority of respondents to the quiz were not deemed to be at high risk, according to the study, which was published Friday in the journal Sexually Transmitted Infections. But women who fell into the high-risk category were four times as likely to test positive for chlamydia, gonorrhea or trichomoniasis than those who were deemed “low risk.” (Respondents were not tested for H.I.V., herpes and syphilis, which require blood samples.)

Over all, 31.4 percent of the high-risk women tested positive for a sexually transmitted infection, compared with 16.3 percent of medium-risk women and 8.7 percent of low-risk women. You can get a zero score if you are at least 25, have had only one sex partner in the last 90 days who is not a new sex partner, have never had an S.T.I. and always use a condom.

S.T.I. risk differs by gender; the cells of the cervix in women, for example, may be particularly susceptible to certain infections like chlamydia. So scores were counted differently for men. Some 13 percent of the high-risk men tested positive for an S.T.I., compared with 5.7 percent of the medium-risk men and 2.8 percent of low-risk men. The results in men were not considered statistically significant, but further studies are being done, and preliminary data presented last September at the World S.T.I. & H.I.V. Conference in Brisbane, Australia, suggests scores are predictive of risk for men as well.

The risk factors for sexually transmitted infections are well known, Dr. Gaydos said. “Studies tell us the same things over and over again: Young age is a risk factor. Not using condoms is a risk factor. Concurrent partners is a risk factor,” she said. The quiz “is a way to get young people diagnosed and get them treated” and could also be used in a doctor’s office, she said.

Teenagers and young adults under 25 account for half of the 20 million cases of sexually transmitted infections that are contracted each year in the United States, though they make up only one-quarter of the sexually active population, according to the Centers for Disease Control and Prevention.

Sexually transmitted infections are often asymptomatic. Many cases of chlamydia and gonorrhea go undiagnosed and can result in long-term consequences, including infertility for women. Syphilis rates have been increasing, particularly among men who have sex with men. If not treated, syphilis increases the risk of contracting H.I.V. and can lead to long-term complications including vision impairment and stroke.

The C.D.C. advises sexually active young women to be tested for chlamydia and gonorrhea once a year if they have a new partner or several partners. Pregnant women should also be tested for syphilis, H.I.V. and hepatitis B. Men who have sex with men should be tested for H.I.V., syphilis, chlamydia and gonorrhea at least once a year, according to the C.D.C.