title: What is the appropriate age range of individuals to be included in a survey to estimate the prevalence of trachomatous trichiasis?
abstract: BACKGROUND
  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.
authors.affiliation: Department of Ophthalmology, University of Melbourne, Level 1, 32 Gisborne Street East, Melbourne, Vic 3002, Australia. j.karimurio@pgrad.unimelb.edu.au
authors.forename: Karimurio
authors.initials: K
authors.lastname: Jefitha
authors.forename: Rono
authors.initials: R
authors.lastname: Hillary
authors.forename: Richard
authors.initials: R
authors.lastname: Le Mesurier
authors.forename: Mutuku
authors.initials: M
authors.lastname: Mwanthi
authors.forename: Jill
authors.initials: J
authors.lastname: Keeffe
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D040362:Geographic Information Systems / Q000706:statistics & numerical data; D006306:Health Surveys / Q000706:statistics & numerical data*; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D018401:Sample Size; D014141:Trachoma / Q000453:epidemiology*; D058457:Trichiasis / Q000453:epidemiology*; D055815:Young Adult