Proton pump inhibitor/histamine-2 receptor blocker exposure and ocular toxoplasmosis: a nationwide claims-based study

This nationwide, population-based, retrospective case-control study investigated the association between proton pump inhibitor (PPI) and histamine-2 receptor blocker (H2B) use and recorded ocular toxoplasmosis diagnosis using Korean National Health Insurance Service data (2002–2021). Among 7,411 patients diagnosed with toxoplasmosis, 3,353 had recorded ocular involvement and 4,058 did not; PPI/H2B exposure during the preceding year was compared between groups. In multivariate logistic regression, older age (40–69 years: odds ratio (OR) = 2.74; ≥70 years: OR = 6.17), hypertension (OR = 1.63), hyperlipidemia (OR = 1.18), and PPI/H2B use for ≥ 8 weeks (OR = 1.50) were associated with higher odds of this diagnosis, while female sex was associated with lower odds (OR = 0.36; all P < 0.05). Propensity score–weighted analyses confirmed this duration-dependent pattern, with higher odds at longer PPI/H2B exposure durations, particularly ≥ 8 weeks. Self-controlled case series analysis showed an increased relative risk (RR) of recorded ocular toxoplasmosis diagnosis during PPI/H2B exposure (RR = 8.26). These findings suggest a possible association between longer PPI/H2B use and recorded ocular toxoplasmosis diagnosis among patients with toxoplasmosis.