Identifying Borderline Trachoma Grades Using a Three-Latent Class Model.

The WHO has a simplified grading system for assessing trachoma. However, even for experts, it can be difficult to classify certain cases as strictly positive or negative for a given grade. Given the absence of a true gold standard, we performed a Latent Class Analysis (LCA) on a set of 200 graded photos of the superior tarsal conjunctiva.