P3.323 Prevalence of Chlamydia Trachomatis in the United States After Adjusting For Sensitivity and Specificity of the Screening Test

According to the Centers for Disease Control and Prevention (CDC), Chlamydia trachomatis infection is among the most prevalent of all sexually transmitted diseases (STDs), and since 1994, has comprised the largest proportion of all STDs reported to CDC. In the past, researchers have used nationally representative surveys, such as, the National Health and Nutrition Examination Survey to estimate chlamydia prevalence and trend under the assumption that the test used to screen for chlamydia has perfect sensitivity and specificity. Under such assumption, the prevalence of chlamydial infection in the U.S. is 2.2% (CI, 1.8% to 2.8%). However, chlamydia screening tests are not perfect tests and thus prevalence estimates must account and adjust for these imperfections. Statisticians have shown that estimates of disease prevalence based on the assumption that screening tests have perfect sensitivity and specificity can be severely biassed. In this work, we use Bayesian methods to provide sensitivity and specificity adjusted estimates of chlamydia prevalence. Based on this method, the adjusted prevalence estimate of chlamydia in the U.S. is 1.1% (CI, 0.002% to 2.02%).