Effects of Cholinesterase Inhibitors on Postoperative Outcomes of Older Adults With Dementia Undergoing Hip Fracture Surgery

Objectives: Cholinesterase inhibitors (ChEIs) may interact with muscle relaxants given during general anesthesia (GA), increasing the risk of postoperative complications. We evaluated the effects of ChEIs on the postoperative outcomes of older adults who underwent hip fracture surgery. Design: Population-based cohort study using linked administrative databases. Participants: All individuals with dementia age 66 years or older, who underwent hip fracture surgery between April 1, 2003, and December 31, 2007, in Ontario, Canada. Exposures: Use of any ChEI (donepezil, rivastigmine, or galantamine) before surgery. Outcomes: The primary composite outcome included any of the following: 30-day postoperative mortality; intensive care unit admissions; or in-hospital resuscitation. Secondary outcomes included postoperative respiratory failure and pneumonia. Analysis: We stratified the study sample on the basis of residence (community or long-term care [LTC]) and type of anesthetic (general or regional) to create four residence/anesthesia groups. We used propensity scores to match users and nonusers of ChEIs within the residence/anesthesia strata. We then calculated the relative risks (RR) and 95% confidence intervals (CI) for outcomes associated with ChEIs in the matched groups. Results: A total of 624 pairs of individuals from the community and 725 pairs from LTC were created among individuals who received GA. High rates of postoperative mortality and complications were observed in both ChEI users and nonusers. The RR of the primary outcome associated with ChEI use for individuals receiving GA was 0.88 (95% CI: 0.68-1.16; chi(2) = 0.93; df = 1; p = 0.34) and 0.82 (95% CI: 0.63-1.04; chi(2) = 2.59; df = 1; p = 0.11) in the community and LTC groups, respectively. In addition, ChEIs were not associated with any significant increased risk of postoperative respiratory complications. Conclusions: ChEI use was not associated with an increased risk of postoperative complications among older adults with dementia who underwent hip fracture surgery. However, the poor postoperative outcomes overall reinforced the need to prevent fractures and improve outcomes in this population. (Am J Geriatr Psychiatry 2011; 19:803-813)