Ear disease, hearing loss, and cognitive outcomes in high school children who were previous participants in a randomized placebo controlled trial of an 11 valent conjugate pneumococcal vaccine administered in infancy.

Background: The WHO estimates that close to 1.7 billion people worldwide have hearing loss; 34 million of whom are children, with 90% residing in low- and middle-income countries. While the effects of ear disease and hearing loss on language, academic, and behavioral development are established, there is remarkably little data on intellectual and other cognitive differences.

Methods: Here we report results from an extension of a randomized controlled vaccination trial originally carried out between 2000 and 2004. Primary caregivers completed demographic and household questionnaires. Beginning in 2016, children were followed up for a hearing and ear disease evaluation. Participants also completed extensive cognitive testing, which included the domains of IQ, language, attention and processing speed, visual and visuospatial skills, and learning and memory. The association between ear disease and hearing loss and each of the cognitive outcomes was examined using multivariate linear regression models.

Findings: We followed up 8926 children ages 14-19 years old. Children with hearing loss or ear disease had lower socioeconomic status compared to children without. However, even after controlling for a high number of covariates, all levels of ear disease or hearing loss were associated with clinically relevant reductions across all cognitive domains, though effect sizes were small. Even mild ear disease or hearing loss was associated with a -0.15 (95% CI: -0.20, -0.11) and a -0.23 (95% CI: -0.32, -0.14) standard deviation reduction, respectively, in IQ. The effects of ear disease and hearing loss were additive as children with both had the lowest cognitive scores.

Interpretation: Untreated ear disease and hearing loss exert measurable effects on cognition that are able to be detected into the teenage years. Early identification of hearing loss and chronic ear disease may have lifelong benefits. Individuals with ear disease and/or hearing loss may require supports and services in addition to those related to speech and language therapy.

Funding: The Bill and Melinda Gates Foundation OPP1142570.