Ethambutol Optic Neuropathy Surveillance: Variations in Real-World Screening Practices and Associated Factors in a Nationwide Cohort Study

Purpose To investigate real-world screening practices for ethambutol optic neuropathy (EON) and how these practices vary across demographic and clinical factors in a nationwide cohort in South Korea. Methods We analyzed data from a cohort of 119,636 individuals in South Korea who initiated ethambutol therapy between January 1, 2015, and December 31, 2021, sourced from the National Health Insurance Review and Assessment (HIRA) database. We compared the screening practices of ethambutol users, focusing on demographic and clinical characteristics between those who underwent baseline examinations (the first ophthalmic examination after starting ethambutol) and those who did not, as well as between individuals who received subsequent monitoring and those who did not. Findings We found significant variations in baseline and subsequent monitoring examinations influenced by factors such as age, sex, geographic location, hospital type, and medical specialty prescribing ethambutol. The results indicated disparities in screening uptake, with younger patients, those in metropolitan areas, and those treated by infectious disease specialists being more likely to undergo baseline examinations. Subsequent monitoring was more common in older patients and those with longer treatment durations. Multivariate analysis revealed that females, individuals receiving ethambutol for non-pulmonary tuberculosis indications or from referral centers, and those residing in metropolitan areas or large cities were less likely to undergo baseline and monitoring examinations. Implications These findings emphasize the need for standardized screening guidelines across different specialties and clinical settings, along with targeted interventions to improve screening, particularly for individuals with lower screening rates, to prevent vision loss in patients undergoing ethambutol therapy.