Abstract
Purpose :
A previous small case series identified a 50% proton pump inhibitor (PPI)/histamine (H2) blocker usage rate in patients with toxoplasma retinochoroiditis, higher than the rate of 20% described in the general population. A primary defense against T. gondii tachyzoites is acidification of phagolysosomes within an acidic environment. Usage of PPI/H2 blockers can increase gastric pH and weaken host defenses, which we hypothesize may increase susceptibility to infection. Therefore, we conducted a case control study of medical claims data from a national database to determine if PPI/H2 blocker usage is associated with the development of ocular toxoplasmosis.
Methods :
A retrospective, matched case control study using data from a medical claims database was performed from 2000-2020. Cases of ocular toxoplasmosis were identified using ICD 9/10 codes. The index date for cases was considered the earliest date of diagnosis of ocular toxoplasmosis. Controls were matched up to 5:1 for age, gender, race, with eligibility date within 3 months from index date of matched cases. Exclusion occurred for being < 18 years old, having congenital toxoplasmosis, having <2 years in the insurance plan prior to the index date and not having at least one visit to an eyecare provider prior to the index date. The primary outcome was defined as having a prescription for PPI or H2 blocker, or a disease that was likely to lead to PPI/H2 blocker use prior to the index date. Multivariate conditional logistic regression analyses were performed controlling for demographic and systemic health variables.
Results :
4069 cases and 19177 controls met our eligibility criteria. 24.3% (989/4069) of ocular toxoplasmosis cases were on PPI/H2 blockers compared to 19.2% (3673/19177) of controls. An adjusted logistic regression model demonstrated a 28% increase in the odds of PPI/H2 blocker use in ocular toxoplasmosis cases compared to matched controls (95% CI: 1.17-1.40, p < 0.001).
Conclusions :
PPI/H2 blocker exposure was associated with ocular toxoplasmosis, corroborating findings from prior case series suggesting an association between the two. Further research studying the mechanisms of PPI/H2 blocker use, gastric acid suppression and T gondii infectivity may help reduce risk of ocular infection.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.