Can we stop mass drug administration prior to 3 annual rounds in communities with low prevalence of trachoma?: PRET Ziada trial results

Abstract

Importance: The World Health Organization recommends at least 3 annual mass drug administrations (MDAs) of azithromycin in places where the prevalence of follicular trachoma (FT) is greater than 10%. However, stopping MDA prior to 3 rounds, if monitoring indicates an absence of infection with Chlamydia trachomatis even if FT persists, may be more cost-effective.

Objective: To determine the prevalence of infection in communities randomized to 3 rounds of annual MDAs with azithromycin compared with communities randomized to a stopping rule, where MDA could cease if the infection rate was low. DESIGN A 1:1 community randomized trial comparing usual care with a cessation rule. The Partnership for the Rapid Elimination of Trachoma-Ziada Trial was conducted from February 1, 2010, through September 1, 2011.

Setting: Sixteen communities in Tanzania with trachoma prevalence rates between 10% and 20%.

Participants: A total of 100 children aged 5 years or younger randomly drawn from each community. Children had to reside in an eligible community, have no ocular condition that prevented trachoma grading or ocular specimen collection, and have a guardian who could provide consent for participation.

Interventions: Cessation of MDA with azithromycin if the community had no infection in their sample at 6 months or 18 months.

Main outcome measure: The prevalence of C trachomatis at 18 months.

Results: None of the intervention communities met criteria to stop MDA based on the 6-month or 18-month survey; all, as well as the usual care communities, were scheduled for a third MDA round. There was no difference in infection (2.9% vs 4.7%; P = .25) between the usual care and cessation rule communities at 18 months.

Conclusions and relevance: In this setting, communities with low (10%-20%) initial prevalence of active trachoma did not have MDA stopped before 3 annual rounds on the basis of monitoring for infection. Infection with C trachomatis in communities with average trachoma rates at 12% to 13% cannot be eliminated before 3 rounds of MDA with azithromycin.

Trial registration: clinicaltrials.gov Identifier: NCT00792922.

Figure 1

Consort diagram of design and characteristics of PRET-Ziada Trial. The usual care group received MDA at baseline and 12 months while the graduation group received antibiotics at baseline but only to received antibiotics at 12 months if infection prevalence was >0% at the 6 month follow-up visit.

Figure 2

A: Prevalence of C. Trachomatis infection over time in Usual Care and Cessation Rule Arms. Thick dashed line indicate mean prevalence in each arm and thin lines indicate village level prevalence b: Prevalence of TF over time in Usual Care and Cessation Rule Arms. Thick dashed lines indicate mean prevalence in each arm and thin lines indicate village level prevalence