(258) The Association between Recently Elevated Anticholinergic Burden and the Risk of Delirium: a case-cross-over study

Publication Number: 1248

Background: Patients using anticholinergic medicines have several comorbidities, which may cause confounding by indications. Although studies have revealed an association between the baseline anticholinergic burden and the risk of delirium, the evidence remains limited.

Objectives: To evaluate the association between anticholinergic burden and the risk of delirium among the older patients in Taiwan.

Methods: We conducted a case-crossover study analyzing the Taiwan National Health Insurance Database (NHID). We selected the cases of patients aged 65+ diagnosed with delirium from 2011 to 2018. We used disease risk score matching to select control patients without the delirium event for a control-crossover analysis. Moreover, we conducted a case-case-time-control analysis by selecting future cases with events within 60-180 days after the matched event date to adjust the time trend. The hazard period was defined as 0-30 days before the event date. The referent periods were defined as a 30-day period selected at random between 60 and 180 days before the delirium diagnostic date. We used the Anticholinergic Cognitive Burden Scale (ACB) and classified the scores into 3+, 1-2, and 0. We performed conditional logistic regression to estimate the odds ratio (OR) and 95% confidence interval between the hazard and referent period. Moreover, we conducted the sensitivity analysis using different scales (the Anticholinergic Drug Scale, the German Anticholinergic Burden Scale, the Modified-ACB, and the Korean Anticholinergic Activity Scale).

Results: We identified a total of 454,476 cases. The average age was 79.7 (SD 8.0). Compared to ACB scoring 0, the case-crossover analysis indicated ACB scoring 1-2 points (OR 1.55; 95% CIs, 1.53-1.58) and 3+ points (OR 2.35; 95% CIs, 2.31-2.38) were associated with a higher risk of delirium. A total of 328,272 control patients and 330,910 future cases were selected. The results remained consistent after adjustments by control-crossover analysis (1-2 points OR 1.24; 95% CIs, 1.21-1.27; 3+ points OR 1.82; 95% CIs, 1.78-1.86) and case-case-time-control analysis (1-2 points, OR 1.06; 95% CIs, 1.03-1.08; 3+ points, OR 1.31; 95% CIs, 1.29-1.34). The results of the sensitivity analysis were consistent to the main analysis.

Conclusions: The results found older patients with a higher anticholinergic burden were associated with an increased risk of delirium. The finding warrants close monitoring for those with a high anticholinergic burden to avoid unintended outcomes.