Open Access

Maria Heinrich, Anika Müller, Andela Cvijan, Rudolf Mörgeli, Jochen Kruppa-Scheetz, Georg Winterer, Arjen J. C. Slooter, Claudia Spies

• Background Postoperative delirium (POD) is a frequent and serious complication after surgery. Evidence of a relationship between anticholinergic medication and the development of delirium is inconclusive, but studies on POD are rare. Objectives The objective of this study was to evaluate the anticholinergic load of preoperative medication in older adult patients and its association with the development of POD. Methods This investigation was part of the European BioCog project (http://www.biocog.eu), a prospective multicenter observational study in older adult surgical patients (ClinicalTrials.gov identifier: NCT02265263, 15 October 2014). Patients with a Mini–Mental State Examination score ≤ 23 points were excluded. POD was assessed up to 7 days after surgery using the Nursing Delirium Screening Scale, Confusion Assessment Method and a patient chart review. The preoperative anticholinergic load was calculated using the Anticholinergic Drug Scale (ADS), the Anticholinergic Risk Scale (ARS) and the Anticholinergic Cognitive Burden Scale (ACBS), and associations with POD were analyzed using logistic regression analysis adjusting for age, comorbidities, duration of anesthesia and number of drugs used. Results In total, 837 participants were included for analysis, and 165 patients (19.7%) fulfilled the criteria of POD. After adjusting for confounders, we found no association between preoperative anticholinergic load and the development of POD (ADS [points] odds ratio [OR] 0.928; 95% confidence interval [CI] 0.749–1.150; ARS [points] OR 0.832; 95% CI 0.564–1.227; ACBS [points] OR 1.045; 95% CI 0.842–1.296). Conclusion This study found no association between the anticholinergic load of drugs used preoperatively and the development of POD in older adult patients without severe preexisting cognitive impairment. Future analyses should examine the influence of intra- and postoperative administration of anticholinergic drugs as well as dosages of and interactions between medications.