Uptake and population-level impact of expedited partner therapy (EPT) on Chlamydia trachomatis and Neisseria gonorrhoeae: the Washington State community-level randomized trial of EPT

Abstract

Background: Expedited partner therapy (EPT), the practice of treating the sex partners of persons with sexually transmitted infections without their medical evaluation, increases partner treatment and decreases gonorrhea and chlamydia reinfection rates. We conducted a stepped-wedge, community-level randomized trial to determine whether a public health intervention promoting EPT could increase its use and decrease chlamydia test positivity and gonorrhea incidence in women.

Methods and findings: The trial randomly assigned local health jurisdictions (LHJs) in Washington State, US, into four study waves. Waves instituted the intervention in randomly assigned order at intervals of 6-8 mo. Of the state's 25 LHJs, 24 were eligible and 23 participated. Heterosexual individuals with gonorrhea or chlamydial infection were eligible for the intervention. The study made free patient-delivered partner therapy (PDPT) available to clinicians, and provided public health partner services based on clinician referral. The main study outcomes were chlamydia test positivity among women ages 14-25 y in 219 sentinel clinics, and incidence of reported gonorrhea in women, both measured at the community level. Receipt of PDPT from clinicians was evaluated among randomly selected patients. 23 and 22 LHJs provided data on gonorrhea and chlamydia outcomes, respectively. The intervention increased the percentage of persons receiving PDPT from clinicians (from 18% to 34%, p < 0.001) and the percentage receiving partner services (from 25% to 45%, p < 0.001). Chlamydia test positivity and gonorrhea incidence in women decreased over the study period, from 8.2% to 6.5% and from 59.6 to 26.4 per 100,000, respectively. After adjusting for temporal trends, the intervention was associated with an approximately 10% reduction in both chlamydia positivity and gonorrhea incidence, though the confidence bounds on these outcomes both crossed one (chlamydia positivity prevalence ratio = 0.89, 95% CI 0.77-1.04, p = 0.15; gonorrhea incidence rate ratio = 0.91, 95% CI .71-1.16, p = 0.45). Study findings were potentially limited by inadequate statistical power, by the institution of some aspects of the study intervention outside of the research randomization sequence, and by the fact that LHJs did not constitute truly isolated sexual networks.

Conclusions: A public health intervention promoting the use of free PDPT substantially increased its use and may have resulted in decreased chlamydial and gonococcal infections at the population level.

Trial registration: ClinicalTrials.gov NCT01665690.

Conflict of interest statement

Pfizer pharmaceuticals provided free azithromycin used in the study. MRG has received research support from Melinta pharmacueticals and Cempra pharmaceuticals for his participation as an investigator in trials of new drug treatments for gonorrhea. MRG has received a consulting fee from Melinta pharmaceuticals.

Figures

Figure 1. Study flow diagram.

Modified for stepped-wedge design from suggested CONSORT criteria format for cluster randomized trials [47]. +Numbers of tests and cases presented as means with ranges.

Figure 2. Washington State local health jurisdictions instituting an expedited partner therapy intervention in four temporally defined waves.

Figure 3. Percentage of persons with gonorrhea or chlamydial infection who received components of the study intervention in periods before and during the study intervention, by study wave.

Percentage of persons receiving (A) PDPT from their diagnosing clinician, (B) public health partner services, or (C) either PDPT or public health partner services. *The percentage of persons receiving partner services was directly measured and is not an estimate. Consequently, there are no confidence intervals on data for this outcome.

Figure 4. Trends in chlamydia test positivity and gonorrhea incidence for 2007–2010 among women in 23 local health jurisdictions in Washington State.

Chlamydia test positivity and gonorrhea incidence (A) across all waves and (B) by wave. Open symbols and red lines indicate measurement and time before the institution of the study intervention, and solid symbols and black lines represent intervention time periods. Time periods are 3-mo analysis periods occurring prior to initiation of the intervention in each wave.