Oral Presentations

O-1: Anticholinergic Potential Risk Assessment Scales: Comparison of Drugs and Risk Scores 

Dr. Tejal Patel

Huyee Chan*, PharmD canD
Tejal Patel, PharmD

University of WaterlooSchool of Pharmacy


Topic: Geriatrics

Drugs with anticholinergic potential have been demonstrated to worsen cognition in older adults.  Although published anticholinergic drug scales offer Canadian clinicians the ability to determine the severity of anticholinergic impact, many scales are not limited to drugs available in Canada. Furthermore, there are inconsistencies in the ratings of severity applied to different drugs in the different scales.  Therefore, there is a lack of applicability in Canada.

The goal of this project was to develop a user-friendly Canadian clinical practice tool that identifies the risk for anticholinergic potential among commonly used drugs.  Additionally, we aim to identify safer alternatives to commonly used highly anticholinergic drugs.

We conducted a literature search to identify scales that examine and assign a potential anticholinergic risk score to drugs.  We limited our search to articles published within the last 20 years that were written in English and based on human data. From each study, we extracted the methodology of developing the scale and their validation studies, if available, for comparison. We also extracted the anticholinergic potential risk scores from these scales for all the drugs, consolidated the drug lists, stratified drugs into 4 groups based on the level of concordance of scores between scales, and selected the relevant drugs available in Canada to include in the clinical practice tool.

A total of 9 scales were included for comparison.  Most scales used a 4-point integer scale of 0-3; however, there was a wide variation of scores for many drugs and drugs assessed in each scale. Similarly, there was significant variation in the methodology used to assign anticholinergic potential risk scores; some used  in-vitro data while others based it on expert opinion. In addition, the definition of “anticholinergic effect” was different for each scale and included cognitive outcomes, adverse events, effect of delirium, or in-vitro anticholinergic activity. We classified 32 drugs as high risk for anticholinergic potential (100% of scales on which it was rated assigned the highest risk score), 18 as intermediate (100% of scales on which it was rated assigned intermediate scores), and 18 as low anticholinergic potential (100% of scales on which it was rated assigned the lowest risk score). These drugs were also required to be listed on at least three scales to ensure there was sufficient data. 168 drugs had undetermined scores due to having disagreeing scores or due to being listed on less than 3 scales. These drugs require further examination to assign a potential anticholinergic risk score.

The lack of consistency between scales in risk score as well as validation in different populations diminishes the clinical applicability and limits the comparability of scores. Future directions include establishing consensus on the anticholinergic potential of drugs and determining safer alternatives for drugs with high and intermediate risk for anticholinergic potential.