How to monitor and evaluate trachoma programmes
Dr Jeremiah Ngondi, Senior Epidemiologist with the Tanzania Vector Control Scale-up Project explains how the Tanzania National Trachoma Programme uses core indicators to plan SAFE interventions and a logic framework to monitor their implementation. He shares guidance on using impact surveys to decide when to stop SAFE interventions and surveillance surveys to obtain pre-elimination validation.
Deciding whether to start SAFE interventions
Baseline surveys must be undertaken before any SAFE interventions are started. Population based surveys are commended using WHO methods.
The key indicators which guide the decision on beginning SAFE interventions are:
Prevalence of active trachoma (TF) ≥ 5% in children aged 1-9 years
Prevalence of trachomatous trichiasis (TT) ≥ 0.2% in people aged 15 years and above
Detailed guidance on how to plan the implementation of SAFE is given in the Trachoma Action Planning guide
Monitoring SAFE interventions
To ensure that SAFE interventions are implemented effectively, periodic monitoring is needed. The range of SAFE activities undertaken are context specific and therefore the monitoring indicators used may vary from place to place. The table below illustrates the logic framework used to monitor SAFE interventions in Tanzania. The framework summarises the inputs, activities, output indicators and outcome indicators.
For instance, in Tanzania, monitoring of mass drug administration (MDA) with azithromycin involves tracking of training activities, doses of azithromycin distributed and calculation of MDA programme coverage.
The results of MDA programme coverage are shared at the district, regional and national levels. Data on coverage is also reported externally to the WHO, International Trachoma initiative and other programme partners. Further monitoring - through population-based coverage surveys - is used to estimates the proportion of population reached by MDA.
Logic framework for monitoring SAFE interventions in Tanzania (Click to expand)
Evaluation of SAFE interventions
Impact surveys are carried out to decide when to stop:
SAFE interventions, and
Periodic surveillance after stopping SAFE interventions.
The key impact indicators which determine whether trachoma is a public health problem are: prevalence of TF of <5% in children aged 1-9 and prevalence of TT of <0.2% in people aged 15+ years.
Trachoma surveys are undertaken by the country programs using the WHO-led initiative, Tropical Data.
Population-based impact surveys are carried out 6 months after the final MDA round to assess the prevalences of TF and TT. Surveys are recommended as follows:
after 1 MDA annual round if baseline TF prevalence = 5-9.9%
after 3 years of MDA if baseline TF prevalence = 10-29.9%
after 5 years of MDA if baseline TF prevalence = 30-49.9%
after 7 years of MDA if baseline TF prevalence ≥ 50%
Once the impact indicators for TF and TT appear to reach the elimination targets, MDA and surgery for TT are stopped. However, F&E interventions should be continued.
Surveillance for trachoma
Trachoma surveillance is the monitoring and evaluation activities which are carried out to assess the outcome of a trachoma elimination programme.
Surveillance begins after elimination prevalence targets appear to have been achieved in a defined trachoma endemic area and S and A interventions have been stopped.
Current guidelines recommend that population-based surveillance surveys should be undertaken at least 24 months after stopping MDA. If a surveillance survey shows that the elimination targets for TF and TT prevalence have been maintained, then trachoma can be considered to have been eliminated as a public health problem from the district. When all endemic districts have achieved elimination, the country is eligible for elimination validation.
Following validation of elimination of trachoma, further routine surveillance is needed to monitor if elimination of trachoma a public health problem is being sustained. this is known as post-validation trachoma surveillance.
A number of approaches have been used in trachoma endemic countries for routine surveillance, including:
- Annual survey of trachoma endemic communities (Australia)
- Sentinel surveillance for active trachoma in a communities (Ghana)
- Routine surveillance for trachoma through health facilities and schools (Oman)
- Active case search for trichiasis in the community (Ghana and Morocco).
Recently, research on the use of antibody-based multiplex assay has showed promising results as an additional tool for evaluating the transmission of trachoma. An indicator for ongoing infection within a community may be useful for additional tracking where elimination of trachoma has been achieved.
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