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A randomized trial of two coverage targets for mass treatment with azithromycin for trachoma
Sheila K West1, Robin Bailey, Beatriz Munoz
1Dana Center for Preventive Ophthalmology, Johns Hopkins University, Baltimore, Maryland, USA. shwest@jhmi.edu
Insights
Higher antibiotic mass drug administration (MDA) coverage for trachoma in children did not significantly reduce infection rates. Three annual rounds of MDA are recommended, even with high coverage, as stopping early showed no benefit.
Area of Science:
- Ophthalmology and infectious disease research.
- Public health interventions for neglected tropical diseases.
Background:
- The World Health Organization recommends annual antibiotic mass drug administrations (MDA) for trachoma control in endemic areas.
- Current guidelines suggest at least 3 annual MDA rounds with ≥80% coverage in children aged 1-9 years.
- The added benefit of enhanced coverage (>90%) and early cessation criteria for MDA is not well-established.
Purpose of the Study:
- To evaluate the impact of enhanced antibiotic mass drug administration (MDA) coverage (>90%) versus usual coverage (80%-90%) on trachoma prevalence.
- To assess the efficacy of early cessation of MDA based on low ocular Chlamydia trachomatis infection prevalence.
Main Methods:
- A 2x2 factorial community-randomized, double-blind trial involving 32 communities with high trachoma prevalence (≥20%).
- Communities were randomized to usual vs. enhanced MDA coverage targets and to 3 years of MDA vs. early cessation based on infection rates.
- The primary outcome was the community prevalence of Chlamydia trachomatis infection at 36 months.
Main Results:
- No community met the criteria for early MDA cessation; all received 3 rounds.
- No significant difference in Chlamydia trachomatis infection prevalence (4.0% vs 5.4%) or trachoma prevalence (6.1% vs 9.0%) between usual and enhanced coverage groups at 36 months.
- Analyzing coverage as a continuous variable also showed no significant impact.
Conclusions:
- In communities with high baseline trachoma prevalence (≥20%), 3 annual rounds of antibiotic MDA are necessary, regardless of coverage level.
- Increasing MDA coverage beyond 90% in children does not provide additional benefit for trachoma control.
- Current evidence does not support early cessation of MDA before 3 rounds, even with high coverage.
Background:
The World Health Organization recommends at least 3 annual antibiotic mass drug administrations (MDA) where the prevalence of trachoma is > 10% in children ages 1-9 years, with coverage at least at 80%. However, the additional value of higher coverage targeted at children with multiple rounds is unknown.
Trial Design:
2 × 2 factorial community randomized, double blind, trial.
Trial Methods:
32 communities with prevalence of trachoma ≥ 20% were randomized to: annual MDA aiming for coverage of children between 80%-90% (usual target) versus aiming for coverag e> 90% (enhanced target); and to: MDA for three years versus a rule of cessation of MDA early if the estimated prevalence of ocular C. trachomatis infection was less than 5%. The primary outcome was the community prevalence of infection with C. trachomatis at 36 months.
Results:
Over the trial's course, no community met the MDA cessation rule, so all communities had the full 3 rounds of MDA. At 36 months, there was no significant difference in the prevalence of infection, 4.0 versus 5.4 (mean adjusted difference = 1.4%, 95% CI = -1.0% to 3.8%), nor in the prevalence of trachoma, 6.1 versus 9.0 (mean adjusted difference = 2.6%, 95% CI = -0.3% to 5.3%) comparing the usual target to the enhanced target group. There was no difference if analyzed using coverage as a continuous variable.
Conclusion:
In communities that had pre-treatment prevalence of follicular trachoma of 20% or greater, there is no evidence that MDA can be stopped before 3 annual rounds, even with high coverage. Increasing coverage in children above 90% does not appear to confer additional benefit.
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