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Association of Preoperative Anticholinergic Medication Exposure With Postoperative Healthcare Resource Use and Outcomes

A Population-based Cohort Study

McIsaac, Daniel I. MD, MPH, FRCPC*,†,‡,§; Wong, Coralie A. MSc; Diep, Deric MD*; van Walraven, Carl MD, FRCPC, MSc†,‡,§,¶

doi: 10.1097/SLA.0000000000002765

Objective: The aim of this study was to measure the association of preoperative anticholinergic exposure with length of stay (LOS) and other outcomes in older people having elective noncardiac surgery.

Summary Background Data: Anticholinergic medications are associated with adverse events in nonsurgical populations; the association of anticholinergic medications with outcomes in elective surgery patients is poorly described.

Methods: We conducted a retrospective, population-based cohort study using linked administrative data in Ontario, Canada. We identified all people >65 years old, from 2003 to 2014, having major, elective noncardiac surgery. Anticholinergic medication exposure was quantified using the Anticholinergic Risk Scale (ARS). Multilevel, multivariable modeling measured the adjusted association of ARS with LOS (primary outcome), institutional discharge, readmissions, costs, and survival (secondary outcomes).

Results: Of 245,410 individuals, 71,569 had anticholinergic exposure (ARS 1–2, 15.6%; ARS ≥3, 13.6%). Median LOS was 5 days (interquartile range 3–7). Using proportional hazards analysis to model time to discharge, adjusting for in-hospital death as a competing risk, and surgical risk, demographic characteristics, and comorbidities, higher ARS scores were associated with longer LOS [smaller hazard ratios (HRs) mean longer LOS; ARS 1–2: adjusted HR 0.94, 95% confidence interval (CI), 0.93–0.95, P < 0.0001; ARS ≥3: adjusted HR 0.93, 95% CI, 0.91–0.95, P < 0.0001]. Similar associations were observed for all secondary outcomes.

Conclusions: Increasing ARS scores were associated with increased LOS, decreased survival, higher rates of institutional discharge and readmission, and higher costs of care. Perioperative interventional research to reduce the anticholinergic exposure in older surgical patients is likely warranted.

*University of Ottawa and The Ottawa Hospital Departments of Anesthesiology & Pain Medicine, Ottawa, Ontario, Canada

Ottawa Hospital Research Institute, Ottawa, Ontario, Canada

Institute for Clinical Evaluative Sciences, Toronto, Canada

§University of Ottawa School of Epidemiology, Public Health and Preventive Medicine, Ottawa, Ontario, Canada

University of Ottawa and The Ottawa Hospital Departments of Internal Medicine, Ottawa, Ontario, Canada.

Reprints: Daniel I. McIsaac, MD, MPH, FRCPC, 1053 Carling Ave, Room B311, Ottawa, ON K1Y 4E9, Canada. E-mail:

Funding: The University of Ottawa Department of Anesthesiology & Pain Medicine. DIM receives salary support from The Ottawa Hospital Department of Anesthesiology, and the Canadian Anesthesiology Society's Career Scientist Award. This study was also supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions, results and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred. These data sets were held securely in a linked, de-identified form and analyzed at the Institute for Clinical Evaluative Sciences. This study used The Johns Hopkins ACG System version 10.

The authors report no conflict of interests.

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