Condom Use at Last Sex as a Proxy for Other Measures of Condom Use: Is It Good Enough?
Younge, Sinead N., Salazar, Laura F., Crosby, Richard F., DiClemente, Ralph J., Wingood, Gina M., Rose, Eve, Adolescence
Condom use provides substantial protection against unintended pregnancies and the transmission of sexually transmitted infections (STIs) including the human immunodeficiency, virus (HIV) (CDC, 2003). To assess condom use frequency, researchers must rely on self-report. The decision confronting researchers is to determine the appropriate length of the recall period for self-reported condom use. Unfortunately, few studies have addressed this question (Cantania et al., 2002; McFarland et al., 1999; Rietmeijer, 2002; Shew, Remafedi, Bearinger, Taylor, & Resnick, 1997). Previous research suggests that self-reported condom use may be subject to recall bias caused by telescoping (i.e., assigning events to the recall period that occurred prior to or after that period) (Ostrow & Kesseler, 1993; Shew et al., 1997). To minimize recall bias, a common practice is to use "the last time sex occurred" as that period (CDC, 2003).
Despite the intuitive appeal of using "last sex" as the recall period, it is not known whether this proxy event is a valid representation of adolescents' condom use behaviors over longer periods of time. Epidemiologic findings indicate that African American adolescent females experience disproportionately higher rates of unintended pregnancies (Ostrow & Kesseler, 1993), STIs, and HIV infection through heterosexual intercourse (CDC, 2004). As a result, African American adolescent females have been purported to have highly variable rates of sexual contact over time (Rietmeijer, 2002). The validity and reliability of a condom use at last sex indicator with expanded recall periods is purported to be compromised by highly variable rates of sexual contact over time in populations such as African American adolescents (Cantania et al., 2002). Accordingly, this study examined whether a single-event recall period (the last time coitus occurred) was consistent with longer recall periods (14 days and 60 days) for a sample of African American adolescent females.
Baseline data collected from 715 African American adolescent females enrolled in a randomized trial of an HIV prevention program were analyzed. Recruiters at clinic sites screened potential participants for eligibility. Eligibility criteria were: African American female, aged 15-21 years, and reporting sexual activity in the previous 60 days. Exclusion criteria were: being married, pregnant, or attempting to become pregnant. Of 1,558 screened, 874 adolescents were eligible and were asked to participate. The Institutional Review Board at Emory University approved the study protocol.
Upon completion of informed written consent, data collection consisted of a 40-minute survey administered via audio computer-assisted self-interviewing (A-CASI) technology. Participants were reimbursed $50 for their time and effort.
Condom use during the last period of sex with a boyfriend or steady sexual partner was assessed. Participants were asked: (a) "Did you use a condom the last time you had vaginal sex with your boyfriend or steady partner?" Frequency of condom use was assessed by asking: (b) "How many times did you have vaginal sex in the past 14 days and during the past 60 days?" and "How many of these times did you use a condom?" The number of times condoms were used was divided by coital frequency to obtain participants' percentage of condom use during coitus for two time periods: the past 14 days and the past 60 days.
Data Analysis Strategy
Descriptive and inferential data analysis techniques were conducted to examine the distribution and relationship among the target variables. These analyses included chi-square analyses to determine condom use at last sex status. Mean comparison tests utilizing independent student t tests to examine group differences in the continuous past condom use variables based on the dichotomous variable condom use at last sex. …