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Angela Nicole Baldwin, Tom Lietman, Alexander Ryner, Zerihun Tadesse, Ayalew Shiferaw, Sintayehu Gebresilassie, Bruce Gaynor, Travis Porco, Paul Emerson, Nicole Stoller, Jeremy D Keenan; A Novel Approach to Trachomatous Scarring Evaluation. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6205.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the validity of a new trachoma scarring ranking system that could be used as an outcome for clinical research.
A convenience sample of individuals aged 10 years and older were selected from 6 Ethiopian villages with hyperendemic trachoma. Each study participant had the upper right tarsal conjunctiva photographed with an SLR camera using a standardized protocol. Photographs were graded by an expert grader for trachomatous scarring according to the 1981 World Health Organization (WHO) grading system, and then each was assigned a rank from least to most scarring. Photographs were ordered masked to the WHO grade, using custom-designed software (Ford Johnson algorithm). External validity was assessed by determining the R2 from a linear regression model assessing the relationship of the scar grade (or ranking) and age. Intra-rater reliability was assessed by masked re-grading of a random 5% of photographs.
The mean age of 427 study participants was 28.7 years (95% CI 27.2 to 30.2). Photographic grading found 79 (18.5%) conjunctivae without scarring (C0), 191 (44.7%) with minimal scarring (C1), 107 (25.0%) with moderate scarring (C2), and 50 (11.7%) with severe scarring (C3). Photographs were ranked from least (rank=1) to most scarring (rank=427). The ranking method had good internal validity, exhibiting a monotonic increase in the median rank across the levels of the 1981 WHO grading system: the median rank for eyes graded as C0 was 62 (interquartile range [IQR] 28 to 102), compared with a median rank of 167 (IQR 110 to 230) for C1, 318 (IQR 274 to 357) for C2, and 401.5 (IQR 378 to 415) for C3. The ranking method had slightly better external validity than the 1981 WHO grading system, accounting for 16.2% of the variance in age compared with 14.1% for the 1981 WHO system. Intra-rater repeatability was good for the 1981 WHO grading system (intraclass correlation coefficient [ICC] 0.74, 95%CI 0.58 to 0.90) but slightly better for the ranking method (ICC 0.84, 95%CI 0.74 to 0.94).
This novel grading methodology to assess trachomatous scarring demonstrated good internal and external validity. Given that the ultimate goal of antibiotic therapy for trachoma is to reduce conjunctival scarring, this grading method could be useful for trachoma studies.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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