Lead author Daniel I. McIsaac, MPH, FRCPC, from the University of Ottawa and the Ottawa Hospital Departments of Anesthesiology & Pain Medicine, Ontario, Canada, and his team explored the impact of an increased preoperative anticholinergic burden and potentially worsened postoperative outcomes. The research was originally highlighted at the 2018 annual meeting of the International Anesthesia Research Society.

The researchers utilized the anticholinergic risk scale (ARS), which was developed to validate the extent of potentially increased risk that an individual is subjected to with the use of anticholinergic medications. The scale considers pharmacokinetic consequences, along with evidence-based clinical risk with assigned points added, to create a final ARS score. It has previously been established that in nonsurgical patients, higher scores are associated with up to 90% more risk of potential adverse effects and up to 30% greater chance of hospital admission with extended length of stay (LOS). However, prior to this research, the impact on elective surgical patients with higher preoperative ARS scores was not known.  

Researchers collected and evaluated data for 245,410 individuals to conduct a retrospective, population-based, cohort study using linked administrative data in Ontario, Canada. Patients were enrolled if they were over age 65 years, had major elective noncardiac surgery, and had taken quantifiable anticholinergic medications before surgery. Of the 245,410 patients, 71,569 had anticholinergic exposure (ARS 1-2, 15.6% and ARS 3 or greater, 13.6%). After adjustment for confounders and competing risks, higher ARS scores were minimally associated with longer LOS, along with additional secondary outcomes that were associated with negative outcomes.

According to the authors, “Given the increasing number of older patients having surgery, and the rising prevalence of poly pharmacy in the older segment of the population, we hypothesized that patients exposed to anticholinergic medications before elective surgery would experience anticholinergic adverse events.”

McIsaac’s research team included members from the Ottawa Hospital Research Institute, Ottawa, Canada; the Institute for Clinical Evaluative Sciences, Toronto, Canada: the University of Ottawa School of Epidemiology, Public Health and Preventive Medicine; and the Ottawa Hospital Departments of Internal Medicine.

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