A new study published in Drug Safety reveals significant limitations in commonly used anticholinergic burden (ACB) scales, showing they fail to fully capture real-world adverse drug reactions (ADRs) associated with anticholinergic medications.
Researchers analyzed over 101,000 cases from the French National Pharmacovigilance Database (FPVD, 1985–2024) involving drugs scored highly on 22 ACB scales or belonging to relevant pharmacological classes, focusing on typical anticholinergic ADRs like confusion, glaucoma, tachycardia, urinary retention, constipation, intestinal obstruction, and mydriasis.
Of 9,629 cases (9.5%) with at least one such ADR, patients had a median age of 61 years (IQR 38–79), with 58% women, demonstrating these reactions affect both younger and older adults, often from single drugs rather than high cumulative burden alone.
Confusion topped the list (4,603 cases, 81% serious), followed by tachycardia (1,541 cases, 70% serious), urinary retention (1,061 cases, 75% serious), and intestinal obstruction (561 cases, 98% serious). Anxiolytics, antidepressants, and antipsychotics dominated implicated classes.
The study highlights discrepancies: Many drugs linked to ADRs in FPVD reports scored low or were absent from popular scales like the Anticholinergic Cognitive Burden scale, underscoring reliance on in vitro data and expert opinion over clinical pharmacovigilance evidence. Scales also overlook class-wide effects, assigning varying scores to similar molecules.
Most patients (92%) experienced one ADR type, but combinations like urinary retention + constipation were common. Serious outcomes underscore clinical urgency, with calls for updated guidelines, better scale validation against real-world data, and heightened prescriber awareness, especially since anticholinergics remain widely used for conditions like overactive bladder, Parkinson's, and psychiatric disorders.
Findings challenge routine ACB assessments in practice, urging integration of national pharmacovigilance insights to refine tools and mitigate risks beyond elderly polypharmacy contexts.
