The effect of the anticholinergic burden on duration and severity of delirium in older hip-surgery patients with and without haloperidol prophylaxis: A post hoc analysis

Background Anticholinergic acting drugs have been associated with delirium in older patients. Objective To examine the association between the anticholinergic burden (ACB) and the duration and severity of delirium in older hip-surgery patients with or without haloperidol prophylaxis. Methods Older patients with a postoperative delirium following hip surgery from a randomized controlled trial investigating the effects of haloperidol prophylaxis on delirium incidence were included in this study. The ACB was quantified using two different tools, the Anticholinergic Drug Scale and an Expert Panel. Using linear regression, the association between the ACB and delirium was analyzed. Results Overall delirium duration and severity were not significantly associated with the ACB. Also, no statistically significant differences were found in delirium duration or severity between the placebo and haloperidol treatment groups for the ACB groups. The protective effect of haloperidol on delirium duration and severity however tended to be present in patients with no or a low ACB but not or to a lesser extent in patients with an intermediate to high ACB. Conclusions The ACB was not significantly associated with delirium duration or severity. Haloperidol prophylaxis tended to shorten delirium duration and decrease delirium severity in patients with no or a low ACB. To further explore the influence of anticholinergic acting drugs on delirium duration and severity and the effect of concomitant haloperidol use, additional research with a higher haloperidol dose, a larger study population, and ACB quantification taking drug exposure into account is warranted.