Design and Baseline Data of a Randomized Trial to Evaluate Coverage and Frequency of Mass Treatment with Azithromycin: The Partnership for Rapid Elimination of Trachoma (PRET) in Tanzania and The Gambia

Abstract

Objectives: Trachoma is the principal cause of infectious blindness. As part of its strategy to eliminate trachoma, the World Health Organization recommends annual mass antibiotic treatment for at least 3 years with an 80% population coverage target. However, to date, ideal population coverage and mass treatment duration have not been determined and further evaluation of treatment recommendations in areas of varying endemicity is warranted. The studies presented here evaluate the impact of coverage level and frequency of mass treatment with single dose azithromycin on trachoma and ocular C. trachomatis infection.

Methods: The Partnership for the Rapid Elimination of Trachoma supervises 2 randomized, community-based clinical trials in Tanzania and The Gambia. Although each trial is a stand-alone effort, protocols, data collection, and analytic approaches have been harmonized to permit generalizations. Communities in each site were randomized using a 2X2 factorial design to standard (80%–90.0%) versus high (over 90.0%) treatment coverage; communities were further randomized to annual treatment for 3 years versus a “graduation” rule where evidence indicates an absence of follicular trachoma or infection and annual treatment is halted.

Results: Average prevalence of follicular trachoma in children age less than 5 years was 32.2% in Tanzania and 5.96% in The Gambia. Randomization appeared to be effective, as prevalence was not statistically different between the arms within each country.

Conclusions: There are challenges in harmonizing 2, large trials in Africa. Study outcomes will provide critical data to national trachoma control programs on treatment methodology and resource allocation toward elimination of the disease.

KEYWORDS::

• C. trachomatis
• Community based trial
• Tanzania
• The Gambia
• Trachoma

ACKNOWLEDGMENTS

The PRET study received operational support from Trachoma Control Programs in Tanzania and The Gambia. The study was funded by the Bill and Melinda Gates Foundation. Dr. West is the recipient of a Senior Scientific Investigator award from Research to Prevent Blindness.

We wish to acknowledge our PRET collaboration partners: on behalf of JHU, Kurt Dreger, Donna Gilbert, and Dr Thomas Quinn, Chair of the PRET Executive Committee; in Tanzania, Harran Mkocha, Wilson Mchiwa, Nicodemus Funga and Catherine Gracewello; on behalf of LSHTM, Tansy Edwards and Dr Sarah Burr (also MRC The Gambia); Gambian NECP, Ansumana Sillah. None of the authors or collaborators report any actual or potential conflicts of interest.

The PRET Data Safety and Monitoring Committee: Douglas Jabs, MD, MBA (Chair), Antoinette Darville, MD, Maureen Maguire, PhD and Grace Saguti, MD.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.