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Pedro Lima Ramos, Rui Santana, Inês Sousa, Amandio A Rocha-Sousa, Antonio Filipe Macedo; Prevalence of Visual Impairment in the Municipality of Braga -Portugal using capture-recapture methods. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1069.
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© ARVO (1962-2015); The Authors (2016-present)
To estimate the prevalence of visual impairment in the general population of a Portuguese municipality using capture-recapture (CR) methods.
Three lists with information about individuals with visual impairment (VI) were obtained. All lists had variables that allowed assessment of repeated cases. Information available included: initials, date of birth, gender, municipality and visual acuity. By matching the three lists, it was possible to ascertain the number of individuals present in all three and the number of individuals present at any combination of two lists. Upon these values, CR methods were applied and the number of individuals missing all three lists was estimated with log-linear models. The Lincoln-Peterson estimator was used to diagnose dependence between all possible combinations of 2 lists.
A list with 556 cases of VI was obtained from the hospital (Hospital de Braga). The second list with 133 individuals was obtained from the Primary Care Centre, also in Braga, and a third list, with 232 subjects, was obtained from ACAPO (blind association). The global prevalence of VI was 1.51% (95% CI, 1.10%-2.26%). The prevalence of VI among subjects with less than 18 years old was 0.15% (95% CI, 0.04%-0.26%). The prevalence for ages between 18 and 49 years was 0.28% (95% CI, 0.24%-0.35%). The prevalence in the population with 50 years or older was 3.69% (95% CI, 2.62%-5.73%).
Our results for the prevalence of VI are in agreement with the known values for other European populations where population-based studies have been conducted. The capture-recapture method allows a better estimation of the prevalence than using simple case counting from list obtained from registers. The use of CR seems to be useful to maintain surveillance of the prevalence of VI in the population.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Venn diagram representing the three lists considered.
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