Incidence and progression of trachomatous scarring in a cohort of children in a formerly hyper-endemic district of Tanzania

Abstract

Purpose : To determine the incidence and progression of trachomatous scarring in a cohort of children residing in a formerly hyper-endemic district where the prevalence of follicular trachoma (TF) is now <5%.

Methods : A cohort of children, ages 1-9 years, were randomly selected at baseline from 38 villages in Kongwa, Tanzania and followed for 2 years. Images were acquired at baseline and graded for the presence and severity of scarring. At two years, another set of images were obtained and graded independently for presence and severity of scarring. Grading of images at both time points was carried out by two standardized graders using a validated five-point scale ranging between S0-S4. Disparate grades were adjudicated. Children without scarring at baseline were at risk for incident scarring and children with scarring at baseline were at risk for progression. Risks were calculated per year.

Results : Of 1496 children, 1266 were followed up at 2 years (85%). The average age of the cohort at baseline was 5.5 years, and 51% were female. The prevalence of scarring at baseline was 1.7% and no child had grade S4 scarring. Nineteen of the children with scarring at baseline were re-examined at follow-up, with 4/19 (21%) found to have more severe scarring. The cumulative incidence of scarring was 1.6% (~0.8%/year). Girls were more likely to develop scars than boys, with an age-adjusted incidence ratio (IR) of 2.9 (95% confidence interval (CI) (1.1 – 8.06)). There was a suggestion of increased risk of incident scarring in villages with TF prevalence at baseline >5%, with an age-adjusted IR of 2.0 (95% CI (0.8 – 5.0)).

Conclusions : The incidence of new scarring in children aged 1-9 years is very low, although 21% of those who had scarring at baseline progressed in severity over the two-year follow-up period.

This is a 2020 ARVO Annual Meeting abstract.