Expert-based drug lists to measure anticholinergic burden: similar names, different results

Background: Scoring scales such as the Anticholinergic Drug Scale (ADS), the Anticholinergic Risk Scale (ARS), and the Anticholinergic Cognitive Burden Scale (ACB) provide an estimation of total anticholinergic burden. Not all the lists include the same drugs, and the points given for certain drugs differ among them. Whether these discrepancies present important differences in the estimation of anticholinergic burden for an individual patient is unknown. Therefore, the aim of this study is to assess agreement among the three scales. Method: Anticholinergic burden was measured with the three scales in 83 patients aged 65years in a medium- and long-stay psychiatric hospital. Subsequently, patients were categorized into three risk categories: low risk (0 points), medium risk (12 points) or high risk (3 or more points). The chance-corrected measures of agreement for the different scores were determined with the k-statistic (kappa). Results: Values for kappa were: 0.19 for Anticholinergic Risk Scale-Anticholinergic Drug Scale, 0.21 for ACB-Anticholinergic Drug Scale and 0.25 for Anticholinergic Risk Scale-ACB. The mean anticholinergic burden measured with ACB was 3.28. Conclusions: There is poor agreement among the three scales. These lists cannot be directly applied to different settings in which drug availability differs substantially, and they require periodic updates. Anticholinergic burden in our setting (psychogeriatric inpatients) was particularly high.