Concurrent Use of Anticholinergic Drugs and Cholinesterase Inhibitors: Register-Based Study of Over 700 000 Elderly Patients

Abstract

Background Although cholinesterase inhibitors are used for the treatment of Alzheimer's disease, the clinical benefits of these drugs are being questioned. Anticholinergic drugs have the opposite pharmacological action to cholinesterase inhibitors, and may antagonize the effects of cholinesterase inhibitors. Therefore, this drug combination should be avoided. Nevertheless, high rates of concurrent use of anticholinergic drugs and cholinesterase inhibitors have been reported in the US. To the authors' knowledge, use of this inappropriate drug combination has not been studied outside North America. Objective To investigate (i) whether anticholinergic drug use is more common among users than non-users of cholinesterase inhibitors, and (ii) which factors are associated with use of anticholinergic drugs among users of cholinesterase inhibitors. Methods We analysed data on age, sex, type of residential area (urban/rural) and drugs dispensed for patients aged>or=75 years registered in the Swedish Prescribed Drug Register from October to December 2005 (n=731,105). The prevalence of use of anticholinergic drugs in users of cholinesterase inhibitors was compared with that in non-users of cholinesterase inhibitors and logistic regression was used to study the association between use of cholinesterase inhibitors and anticholinergic drugs. Logistic regression was also used to analyse whether age, sex, type of residential area or number of dispensed drugs was associated with use of anticho…