Can We Measure STD Risk Behavior or STD as Surrogates for HIV risk? Presented at the International Congress of Sexually Transmitted Infections (ISSTDR/IUSTI) 2001, Berlin : Presented at the International Congress of Sexually Transmitted Infections (ISSTDR/IUSTI) 2001, Berlin.

There is great interest in the development of surrogate measures for HIV infection that could be used in intervention trials. The sample size needed to detect a change in HIV incidence may be 10 times larger than the sample needed to detect a change in STD (sexually transmitted disease) incidence, and 200 times larger than that needed to detect a change in behavior. We do not know how accurately we can measure sexual behavior. We know many factors that influence responses to questions. Although behavior is clearly associated with STD and HIV, acquisition of disease requires sexual contact with an infected person. Questionnaires have been unable to satisfactorily measure the prevalence of infection in a person's partners. Behavior is not a good surrogate for STD or HIV because behavior change interventions can change question answering behavior, and people have safe sex with risky partners and risky sex with safe partners. STD are not a good surrogate for HIV if the intervention influences STD treatment, if protective behaviors such as condom use influence some STD more than others, or if HIV specific interventions are used, such as deciding to have sex without a condom if a partner has a negative HIV test.