Anticholinergic Medication Burden Scales: A Systematic Review

BACKGROUND: Anticholinergic burden refers to the cumulative anticholinergic effect of all medications taken by an individual. Anticholinergic burden scales help identify patients at risk of anticholinergic adverse effects and guide prescribing. However, substantial variation exists between scales, with no gold standard identified. This variability may contribute to inconsistent risk assessment, suboptimal prescribing, and adverse outcomes. AIM: To systematically review available anticholinergic burden scales and their variability in medication lists, development strategies and scoring methods. As a secondary objective, the clinical outcomes associated with each scale were summarized. METHODS: A systematic search was conducted up to January 2025. Studies proposing novel or updated anticholinergic burden scales were included. Two reviewers independently performed study selection, data extraction, and quality assessment, using a custom tool based on expert consensus and principles of scale development. Findings were narratively synthesized. RESULTS: From 10,969 identified records, 21 studies met inclusion criteria. Medications included per scale ranged from 27 to 217, with 74% of high-potency drugs scored inconsistently. Variability was influenced by geographical origin and methodology, with literature review followed by expert opinion the most common method of development. Dosage consideration, among others, was inconsistent across scales, affecting clinical relevance. Clinical outcome studies reflected such inconsistencies. CONCLUSION: No gold standard anticholinergic burden scale was identified. Scales with broader drug coverage and accounting for individual variability appeared more clinically relevant. This review highlights the need for a clinically accessible, universal scoring system to better address the risks associated with anticholinergic polypharmacy.