Anticholinergic burden of long-term medication is an independent risk factor for the development of postoperative delirium: A clinical trial

Background: Postoperative delirium (POD) is a common complication after surgery.

Objective: We sought to determine the association between preoperative anticholinergic load calculated using the anticholinergic drug scale (ADS) and POD in cancer patients over 65 years of age.

Design: A retrospective sub-investigation of a randomised controlled interventional trial.

Setting: Two tertiary university hospitals.

Patients: Overall, patients aged 65 years and older scheduled for surgical treatment of gastrointestinary, genitourinary or gynaecological cancers.

Main outcome measures: The primary outcome was the interaction between anticholinergic drug scale and occurrence of postoperative delirium. Patient clinical parameters and ADS scores were assessed preoperatively. POD screening was conducted for a total of 7 days following surgery using validated measures. Independent associations between ADS and POD were assessed using multivariate logistical regression analyses.

Results: A total of 651 patients (mean age, 71.8 years; 68.5% males) were included. Of those, 66 patients (10.1%) developed POD. The ADS score was independently associated with the occurrence of POD (higher ADS per point OR 1.496; 95% CI 1.09-2.05; p = 0.01). Additionally, age (per year OR 1.06; CI 95% CI 1.01-1.11; p = 0.03) and ASA state (OR 2.16; 95% CI 1.22-3.83; p = 0.01), as well as stay on ICU (yes vs. no OR 2.8; 95% CI 1.57-4.998; p < 0.01), were independently associated with POD.

Conclusions: ADS assessment according to chronic medication use is a cost-effective, non-invasive method of identifying elderly cancer patients at risk for POD.

Trial registry: www.clinicaltrials.gov. Identifier NCT01278537. Ethics: IRB of Charité University-Medicine Berlin, Germany; EA2/241/08.