Previous clinical diagnosis of chlamydia helps patients predict outcome of new chlamydia clinical test

Background: As part of an ongoing clinical trial evaluating the effectiveness of an intervention aimed at decreasing STDs in adolescent females, a host of different background measures were collected at baseline. These measures include self-reported behaviors, risk and probability estimates concerning STDs, self-reported prior medical diagnoses, and a Chlamydia trachomatis (Ct) infection assay, among other measures. This analysis examines participants' accuracy in estimating their own chance of chlamydia infection.Methods: Participants were 131 sexually active adolescent females, 79% black, 13% white, mean age 16 (range 13-19), who had been recruited from an adolescent health service. At the time of this study, participants were not primarily being seen for a clinical visit. Participants answered two questions that are examined here: The first asked, "What is the percent chance that you have chlamydia right now," accompanied by a visual scale ranging from 0% (no chance) to 100% (certainly). The second question asked, "In your life, have you ever been told by a doctor or nurse that you had chlamydia?" Following all questions a vaginal swab was collected by the participant, which was analyzed by polymerase chain reaction (PCR) for Ct. A multiple regression was performed, predicting the outcome of the chlamydia swab test using participants' estimates that they had chlamydia, their self-reported prior diagnosis with chlamydia (dichotomous), and the interaction between these two variables.Results: The regression F(3, 127) = 10.95, p