Late HIV Presentation Remains High in Korea: 28-Year National Surveillance Trends and the Limits of Inference under Incomplete CD4 Capture, 1998-2025.

backgroundWhether late human immunodeficiency virus (HIV) presentation in Korea has improved is difficult to judge because a CD4 count at diagnosis was captured for only a minority of notified cases until 2025. We examined 28-year trends in late presentation (CD4 <350 cells/µL) and advanced HIV disease (AHD; CD4 <200 cells/µL) among cases with a captured CD4 result, quantified how incomplete and time-varying capture limits inference about population-level trends, and characterized the burden in 2025, the year of highest CD4 capture (80.4%). MATERIALS AND

methodsWe analyzed national HIV/acquired immunodeficiency syndrome (AIDS) notification data from the Korea Disease Control and Prevention Agency (1998-2025). Annual proportions among captured cases were modeled with overdispersion-adjusted logistic regression and adjusted for mean age and for the annual uncaptured fraction; change-points were identified by joinpoint regression. Missing CD4 values were treated as incomplete capture; distribution-free Manski bounds were computed for every year, with a missing-not-at-random tipping-point analysis and a sensitivity analysis for recent infection.

resultsAmong captured cases, late presentation showed no significant change (odds ratio [OR] per year, 1.008; 95% confidence interval [CI], 0.995-1.021;

conclusionIn 2025, approximately half to two-thirds of new HIV diagnoses in Korea were late and one-third to one-half had advanced disease, above contemporary European levels and far above the World Health Organization European target. Whether this burden has improved cannot be determined from surveillance data, because captured-only trends track the completeness of CD4 capture. Late-presentation indicators should be reported together with capture completeness, and cohort data with complete CD4 ascertainment are needed to establish the trend.