Use of medications with anticholinergic effect predicts clinical severity of delirium symptoms in older medical inpatients

Background: Use of anticholinergic (ACH) medications is a biologically plau sible and potentially modifiable risk factor of delirium, but research find ings are conflicting regarding its association with delirium. Objectives: To evaluate the longitudinal association between use of ACH med ications and severity of delirium symptoms and to determine whether this as sociation is modified by the presence of dementia. Patients and Methods: A total of 278 medical inpatients 65 years and older with diagnosed incident or prevalent delirium were followed up with repeate d assessments using the Delirium Index for up to 3 weeks. Exposure to ACH a nd other medications was measured daily. The association between change in medication exposure in the 24 hours preceding a Delirium Index assessment w as assessed using a mixed linear regression model. Results: During follow-up (mean +/- SD, 12.3 +/-7.0 days), 47 medications w ith potential ACH effect were used in the population (mean, 1.4 medications per patient per day). Increase in delirium severity was significantly asso ciated with several measures of ACH medication exposure on the previous day , adjusting for dementia, baseline delirium severity, length of follow-up, and number of non-AGH medications taken. Dementia did not modify the associ ation between ACH medication use and delirium severity. Conclusion: Exposure to ACH medications is independently and specifically a ssociated with a subsequent increase in delirium symptom severity in elderl y medical inpatients with diagnosed delirium.