Abstract
Histamine-2 receptor antagonists are commonly administered for stress ulcer prophylaxis in critically ill adults and may be associated with delirium development. We aimed to determine differential associations of histamine-2 receptor antagonist or proton-pump inhibitor administration with delirium development in patients admitted to a medical ICU. DESIGN: Retrospective observational study using a deidentified database sourced from the University of North Carolina Health Care system. Participants were identified as having delirium utilizing an International Classification of Diseases-based algorithm. Associations among histamine-2 receptor antagonist, proton-pump inhibitor, or no medication administration and delirium were identified using relative risk. Multiple logistic regression was used to control for potential confounders including mechanical ventilation and age. SETTING: Academic tertiary care medical ICU in the United States. PATIENTS: Adults admitted to the University of North Carolina medical ICU from January 2015 to December 2019, excluding those on concurrent histamine-2 receptor antagonists and proton-pump inhibitors in the same encounter. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We identified 6,645 critically ill patients, of whom 29% (n = 1,899) received mechanical ventilation, 45% (n = 3,022) were 65 or older, and 22% (n = 1,487) died during their medical ICU encounter. Of the 6,645 patients, 31% (n = 2,057) received an histamine-2 receptor antagonist and no proton-pump inhibitors, 40% (n = 2,648) received a proton-pump inhibitor and no histamine-2 receptor antagonists, and 46% (n = 3,076) had delirium. The histamine-2 receptor antagonist group had a greater association with delirium than the proton-pump inhibitor group compared with controls receiving neither medication, after controlling for mechanical ventilation and age (risk ratio, 1.36; 1.25-1.47; p < 0.001) and (risk ratio, 1.15; 1.07-1.24; p < 0.001, respectively). CONCLUSIONS: Histamine-2 receptor antagonists are more strongly associated with increased delirium than proton-pump inhibitors. Prospective studies are necessary to further elucidate this association and to determine if replacement of histamine-2 receptor antagonists with proton-pump inhibitors in ICUs decreases the burden of delirium in critically ill patients.