Optimising age adjustment of trichiasis prevalence estimates using data from 162 standardised surveys from seven regions of Ethiopia.

PURPOSE: The prevalence of trichiasis is higher in females and increases markedly with age. Surveys carried out in the daytime, particularly in developing countries, are prone to find older individuals and females at home at the time of the survey. Population-level trichiasis estimates should adjust sample proportions to reflect the demographic breakdown of the population, although the most accurate method of doing this is unclear. METHODS: Having obtained data from 162 surveys carried out in Ethiopia as part of the Global Trachoma Mapping Project from 2012 to 2015, we used internal validation with both Brier and Logarithmic forecast scoring to test stratification models to identify those models with the highest predictive accuracy. Selection of partitions was undertaken by both simple random sampling (SRS) and cluster sampling (CS) over 8192 selections. RESULTS: A total of 4529 (1.9%) cases of trichiasis were identified from 241,139 individuals aged ≥15 years from a total of 4210 kebeles and 122,090 households visited. Overall, the binning method using 5-year bands from age 15 to 69 years, with coarser binning in 20-year age-bands above this age, provided the best predictive accuracy, in both SRS and CS methodologies and for both the Brier and Logarithmic scoring rules. CONCLUSION: The greatest predictive accuracy for trichiasis estimates was found by adjusting for sex and in 5-year age-bands from the age of 15 to 69 years and in 20-year age-bands in those aged 70 years and greater. Trichiasis surveys attempting to make population-level inferences should use this method to optimise surgery backlog estimates.

Prevalence of and Risk Factors for Trachoma in Oromia Regional State of Ethiopia: Results of 79 Population-Based Prevalence Surveys Conducted with the Global Trachoma Mapping Project.

PURPOSE: To complete the baseline trachoma map in Oromia, Ethiopia, by determining prevalences of trichiasis and trachomatous inflammation - follicular (TF) at evaluation unit (EU) level, covering all districts (woredas) without current prevalence data or active control programs, and to identify factors associated with disease. METHODS: Using standardized methodologies and training developed for the Global Trachoma Mapping Project, we conducted cross-sectional community-based surveys from December 2012 to July 2014. RESULTS: Teams visited 46,244 households in 2037 clusters from 252 woredas (79 EUs). A total of 127,357 individuals were examined. The overall age- and sex-adjusted prevalence of trichiasis in adults was 0.82% (95% confidence interval, CI, 0.70-0.94%), with 72 EUs covering 240 woredas having trichiasis prevalences above the elimination threshold of 0.2% in those aged ≥15 years. The overall age-adjusted TF prevalence in 1-9-year-olds was 23.4%, with 56 EUs covering 218 woredas shown to need implementation of the A, F and E components of the SAFE strategy (surgery, antibiotics, facial cleanliness and environmental improvement) for 3 years before impact surveys. Younger age, female sex, increased time to the main source of water for face-washing, household use of open defecation, low mean precipitation, low mean annual temperature, and lower altitude, were independently associated with TF in children. The 232 woredas in 64 EUs in which TF prevalence was ≥5% require implementation of the F and E components of the SAFE strategy. CONCLUSION: Both active trachoma and trichiasis are highly prevalent in much of Oromia, constituting a significant public health problem for the region.

The Global Trachoma Mapping Project: Methodology of a 34-Country Population-Based Study.

PURPOSE: To complete the baseline trachoma map worldwide by conducting population-based surveys in an estimated 1238 suspected endemic districts of 34 countries. METHODS: A series of national and sub-national projects owned, managed and staffed by ministries of health, conduct house-to-house cluster random sample surveys in evaluation units, which generally correspond to "health district" size: populations of 100,000-250,000 people. In each evaluation unit, we invite all residents aged 1 year and older from h households in each of c clusters to be examined for clinical signs of trachoma, where h is the number of households that can be seen by 1 team in 1 day, and the product h × c is calculated to facilitate recruitment of 1019 children aged 1-9 years. In addition to individual-level demographic and clinical data, household-level water, sanitation and hygiene data are entered into the purpose-built LINKS application on Android smartphones, transmitted to the Cloud, and cleaned, analyzed and ministry-of-health-approved via a secure web-based portal. The main outcome measures are the evaluation unit-level prevalence of follicular trachoma in children aged 1-9 years, prevalence of trachomatous trichiasis in adults aged 15 + years, percentage of households using safe methods for disposal of human feces, and percentage of households with proximate access to water for personal hygiene purposes. RESULTS: In the first year of fieldwork, 347 field teams commenced work in 21 projects in 7 countries. CONCLUSION: With an approach that is innovative in design and scale, we aim to complete baseline mapping of trachoma throughout the world in 2015.