What is the appropriate age range of individuals to be included in a survey to estimate the prevalence of trachomatous trichiasis?

摘要

INTRODUCTION: A survey to determine the prevalence of trachomatous trichiasis (TT) requires a large sample size and the recommended participant age is >/=15 years. This study sought to establish the appropriate age range of individuals to be included in TT surveys. METHODS: Data from six previous surveys of adults >/=15 years old were reanalysed. RESULTS: Reanalysis indicated that 69.6-93.3% (average 87.0%) of untreated TT occurred in those aged 40+ years and 52.2-86.7% (average 73.1%) in those aged 50+ years (age >/=50 years is used in rapid assessment of avoidable blindness). Age >/=40 years was adopted in a TT survey conducted in Turkana district because it allowed a smaller sample size than age >/=15 years. CONCLUSIONS: The estimated backlog of untreated TT in people aged >/=40 years old in Turkana was 5932 and the overall TT backlog was likely to be 6358-8523. These findings cannot be generalised because all surveys were carried out in the same country.