Age, Sex, and Cohort Effects in a Longitudinal Study of Trachomatous Scarring

Abstract

PURPOSE To determine the 5-year incidence rate of scarring, and associated factors, in the population of Maindi, Tanzania. METHODS A census of every resident was obtained at baseline, and ocular examinations for the presence and severity of trachoma were performed. Images of the upper eyelid were taken and graded for the presence and severity of scarring, according to a four-step severity scale based on photographs. Five years after baseline, a second series of images was taken and graded for scarring. Incident scarring was defined as new scars in those without scarring at baseline; progression was defined as those with scars that worsened by one step or more at 5 years. RESULTS The rate of scarring at baseline increased with age, from 1% in the < 6-year to 38% in the 41 +-year age group. Females at any age had more scarring than did males. The 5-year incidence rate of scarring was 0.20 (95% confidence interval [CI], 0.16–0.25), but varied with age up to 0.43 in the 41 +-year group. There was a striking cohort effect, with those aged less than 16 years at baseline having more prevalent scarring and incidence rates comparable to those aged 16 to 40. Progression rates averaged 0.47 (95% CI, 0.36–0.58). CONCLUSIONS In this trachoma-endemic community, incident scarring was high, especially in the younger cohorts. A dramatic increase in risk of trachomatous scarring occurred approximately 15 years ago and appears to be unabated. Trachoma control programs to reduce risk of scarring are urgently needed to avoid blinding complications in this community.

Clinical signs of trachoma are prevalent among Solomon Islanders who have no persistent markers of prior infection with Chlamydia trachomatis

“…Contrary to what might be expected in a trachoma-endemic community 13 , no eyelid-distorting scars were found in 311 adults aged above 40 years. Some cases of severe scarring we observed in children were not typical of trachoma and were found in children who lacked Pgp3 reactivity ( Figure 1, Table 2).…”

Age-specific prevalence of anti-Pgp3 antibodies and severe conjunctival scarring in the Solomon Islands

“…Analysis of the age-specific prevalence of conjunctival scarring illustrated that, while the proportion of people with mild scars increased with age, the proportion of those with more extensive or eyelid-distorting scars did not increase with age. Contrary to what might be expected in a trachoma-endemic community 30 , no eyelid-distorting scars were found in 311 adults >40 years. There does appear to be severe scarring among children, but some cases are atypical (Figure 3) and are in children who lack Pgp3 reactivity (Table 3), so other causes of scarring may be contributing to this (presumed) ongoing incidence.…”

Changes in the Prevalence of Visual Impairment Due to Blinding Trachoma in Sichuan Province, China: A Comparative Study Between 1987 and 2006

“…This is consistent with findings from studies done in Beijing city, 15 and it appears to be a reflection of past hyper-endemic distribution. [50][51][52] Our surveys suggest that more focus and care should be given to females and people in rural areas. 1 Although our study was not a cohort study in its strict sense, younger age groups in 1987 became older by 2006, which allowed for interesting comparisons, e.g., age ≤19 in 1987 with 20≤ age ≤39 in 2006, etc.…”