Examining long-term chlamydia prevalence and case rate trends among young adults in the United States Public Deposited

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  • March 20, 2019
  • Learner, Emily
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
  • Chlamydia trachomatis (chlamydia) is a sexually transmitted infection that is usually asymptomatic but can result in serious reproductive sequelae if left untreated. Screening and treating sexually active young adults for chlamydia helps prevent transmission and reduces incidence and prevalence. Monitoring prevalence and case rate trends through surveillance is important for assessing screening effectiveness. However, trends from surveillance data are difficult to interpret because they are influenced by important time-varying biases. The purpose of this dissertation was to 1) estimate chlamydia prevalence trends among a sentinel population of young adults, accounting for bias from changing risk profiles (case mix) and imperfect screening tests, and 2) estimate the annual incidence rate of correctly diagnosed chlamydia that would be obtained with perfect screening coverage, screening tests, and case reporting. For the first objective, we estimated prevalence among young women and men entering the National Job Training Program from 1990 through 2012. We examined the distribution of enrollment by race/ethnicity and region over time to assess case mix, and corrected for time-varying measurement error introduced by increasingly sensitive screening tests. For the second objective, we estimated bias due to screening coverage, screening tests, and reporting, and corrected annual chlamydia case rates from 2000 through 2015 among young women using a series of corrections. Chlamydia prevalence trends among high-risk young women declined from 20% in 1990 to 12% in 2003, and were relatively stable from 2004 through 2012. Trends among men were stable over the course of the study at approximately 7%. Prevalence was highest among Black women and men, and in the Southern and Midwestern regions of the US. Counterfactual incidence rates of correctly diagnosed chlamydia among young women were higher than reported case rates, and declined from 12,900 cases per 100,000 person-years in 2000 to 7,100 cases per 100,000 person-years in 2015. Trends declined sharply from 2000 through 2007, and modestly from 2008 through 2015. Declining chlamydia prevalence and counterfactual incidence rate trends suggest that screening programs may have initially been effective at reducing chlamydia burden, but relatively stable trends in more recent years signal that screening may be losing momentum.
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  • In Copyright
  • Fine, Jason
  • Powers, Kimberly
  • Torrone, Elizabeth
  • Miller, William
  • Pence, Brian
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017

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