Temporal trends in anticholinergic medication prescription in older people: repeated cross-sectional analysis of population prescribing data

Background: in older people, medications with anticholinergic (antimuscarinic) effects are associated with adverse clinical outcomes, the risk increasing with increasing anticholinergic exposure. Many anticholinergics are recognised as potentially inappropriate and efforts to reduce prescription have been ongoing. We examined temporal trends of anticholinergic prescription and exposure in older people. Methods: anonymised data on all prescribed medication dispensed to people ≥65 years in Tayside, Scotland were obtained for the years 1995 (n = 67,608) and 2010 (n = 73,465). The Anticholinergic Risk Scale (ARS) was adapted (mARS) to include newer medications and medications identified in other scales as having moderate to strong anticholinergic activity. An individual's mARS score was the sum of scores for individual medications. Differences in prescription of anticholinergic medications and mARS scores between 1995 and 2010 were examined. Results: a significantly higher proportion of older people received any anticholinergic medication in 2010 compared with 1995 (23.7 versus 20.7%; P < 0.001). High anticholinergic exposure (mARS scores ≥3) was seen in 7.3% in 1995 and 9.9% in 2010 (P < 0.001). Prescription of individual anticholinergic medication was small-only three medications were prescribed to >2% of people. The risk of high anticholinergic exposure increased in those with polypharmacy, social deprivation, those living in care homes and women. Conclusion: despite increasing evidence of adverse outcomes, the proportion of older people prescribed anticholinergic medications and the proportion with a high anticholinergic exposure has increased between 1995 and 2010. Prescription of individual drug is small so cumulative anticholinergic scores may help future efforts to reduce anticholinergic prescription in older people.