[Risk/benefit assessment in the treatment of Alzheimer's disease. Drug interactions]

Anticholinergic drugs reduce the efficacy of acetylcholinesterase inhibitors (AChEI) and are inappropriate in elderly patients. The aim of this study is to determine the prevalence rate of prescription AChEI drugs and anticholinergics in a Healthcare Area, to identify the affected patients, and to inform the attending physicians, in order to evaluate the suitability of treatments.

A descriptive cross-sectional observational study of prevalence. Patients on treatment with AChEI and any anticholinergic drug in the first quarter of 2015 were selected. The review of Duran et al. was used as reference to identify anticholinergics, assigning a score to each drug according to its anticholinergic potency. Physicians were provided with a report about the interaction, the list of affected patients, and recommendations.

A total of 486 patients were included in the study, representing 59.0% of total patients with Alzheimer's disease in the Area. There were 66.0% women, and 86.8% of the patients were older than 75 years, and with a mean of 9.2 drugs per patient. The mean number of anticholinergic drugs was 1.6, and 38.3% of patients were prescribed various anticholinergic drugs, with 23.9% on high potency anticholinergic drugs. A statistically significant association was found between taking an anticholinergic and AChEI concomitantly (P=.000; OR: 3.9).

The prevalence of interactions between AChEI and anticholinergic drugs is relevant, considering that it affects vulnerable members of the population. Providing physicians with information about the interaction could help them make clinical decisions, and could improve patient safety, as well as health outcomes.