Relationship between angiotensin-converting enzyme inhibitors and angiotensin receptor blockers prescribing and delirium in the ICU-A secondary analysis

Background: Studies suggest Angiotensin-Converting Enzyme inhibitors (ACEI) and Angiotensin Receptor Blockers (ARB) may slow the decline of memory function in individuals with mild to moderate Alzheimer's disease by regulating migroglial activation and oxidative stress within the brain's reticular activating system. Therefore, we evaluated the relationship between delirium prevalence and being prescribed ACEI and ARB in participants admitted to the intensive care units (ICU).Methods: A secondary analysis of data from two parallel pragmatic randomized controlled trials was performed. ACEI and ARB exposure was defined as being prescribed an ACEI or an ARB within six months prior to the ICU admission. The primary endpoint was the first positive delirium assessment based on Confusion Assessment Method for the ICU (CAM-ICU) for up to thirty days.Results: A total of 4791 patients admitted to the medical, surgical, and progressive ICU and screened for eligibility for the parent studies between February 2009 and January 2015 from two level 1 trauma and one safety net hospital in a large urban academic health system were included. Delirium rates in the ICU were not significantly different among participants with no exposure to ACEI/ARB (12.6%), or exposure to ACEI (14.4%), ARB (11.8%), or ACEI and ARB in combination (15.4%) in six months prior to the ICU admission. Exposure to ACEI (OR = 0.97[0.77, 1.22]), ARB (OR = 0.70 [0.47, 1.05]), or both (OR = 0.97 [0.33, 2.89]) in six months prior to ICU admission was not significantly associated with odds of delirium during the ICU admission after adjusting for age, gender, race, co-morbidities, and insurance status.Conclusions: While the impact of ACEI and ARB exposure prior to the ICU admission was not associated with the prevalence of delirium in this study, further research is needed to fully understand the impact of antihypertensive medications on delirium.