FIG 1.

Predicted probability of a positive EIA result as a function of LA titer demonstrates reduced sensitivity of the EIA. The predicted probability of a positive enzyme immunoassay (EIA) result for cryptococcal antigen was determined as a function of the latex agglutination (LA) titer from the blood (solid line) and cerebrospinal fluid (CSF) (dashed line) among a cohort of patients with cryptococcosis without known immunocompromising conditions. The model was fit such that the probability of a positive EIA was exp(θ)/[1 + exp(θ)], where θ = −3.828 + 0.817 × log₂(LA) in the blood and θ = −1.722 + 0.917 × log₂(LA) in the CSF. The actual data are depicted as circles in which each circle represents one person. The size of the circle is based on the number of LA and EIA pairs for that person and specimen type, with the average LA value as a proportion of EIAs that were positive. Specimens testing negative by LA are represented by circles centered at the origin.