Asking only "Did you use a condom?" underestimates the prevalence of unprotected sex among perinatally HIV infected and perinatally exposed but uninfected youth.

Among young adults who use condoms, incomplete condom use (putting a condom on after beginning or taking a condom off before finishing sex) and condom failure (condom breaking or slipping off during sex) are common. Therefore, sexual behavior surveys that ask only if a condom was used are likely to underestimate the actual prevalence of unprotected sex. This study examined data from 135 sexually active perinatally HIV-infected (PHIV+) youth and perinatally exposed but uninfected (PHIV-) youth, ages 13 to 24. Participants were asked whether they used a condom on their first and their most recent occasion of vaginal sex. Youth who reported using a condom were asked a follow-up question about whether there was any time during that occasion when sex was not protected by a condom. This follow-up question identified additional participants--almost double the proportions who initially said they did not use a condom--who had unprotected sex. Incomplete condom use was similar among PHIV+ and PHIV-youth, boys and girls, Latinos and African Americans, and younger and older youth. These findings illustrate the importance of asking specifically about whether any unprotected behavior occurred from start to finish of sex to achieve more valid estimates of sexual risk behavior.