Anticholinergic burden and frailty in older inpatients: insights from analysis of admission and discharge medicines using four anticholinergic scales

Background: Exposure to high anticholinergic burden is associated with adverse outcomes in older adults. Older adults with frailty have greater vulnerability to adverse anticholinergic effects. There is limited data on anticholinergic burden in hospitalised older adults with frailty particularly, in New Zealand. This study aimed to (i) examine exposure to anticholinergic medicines in older inpatients using multiple scales, and (ii) describe the association of patient factors such as frailty with anticholinergic exposure.

Methods: We reviewed admission and discharge medicines of 222 older patients (≥ 65 years) in a New Zealand hospital. Sociodemographic, diagnostic and medication data were collected from electronic health records. Anticholinergic burden was quantified using the Anticholinergic Burden Classification (ABC), Anticholinergic Cognitive Burden Scale (ACB), Anticholinergic Risk Scale (ARS), and Drug Burden Index (DBI). Frailty was assessed using frailty index (FI) and the Hospital Frailty Risk score (HFRS); higher scores indicate higher frailty. Multivariable logistic regression analysis was used to determine patient factors associated with anticholinergic burden.

Results: Depending on the scale used, the mean anticholinergic burden ranged from 0.65 to 1.83 on admission and 0.59 to 1.40 at discharge, with 32-74% of the patients on admission and 25-65% at discharge prescribed at least one anticholinergic medicine. About 1 in 3 patients had high anticholinergic burden on admission and discharge. On admission, being frail (adjusted odds ratio [AOR] 5.16, 95% confidence interval [95% CI] 1.57, 16.97), having history of readmission (AOR 4.96, CI 1.58, 15.59), and higher number of medicines [AOR range 1.18 CI 1.10, 1.26 (ARS scale) to 1.25 CI 1.15, 1.36 (DBI scale)] were associated with higher odds of anticholinergic exposure. At discharge, pre-frail (DBI scale: AOR = 6.58, CI 1.71-25.32) and frail patients (ACB scale: AOR = 5.73, CI 1.66, 19.70) and those with higher number of medicines [AOR range 1.18 CI 1.09, 1.29 (ARS scale) to 1.33 CI 1.20, 1.49 (DBI scale)] had higher odds of anticholinergic exposure.

Conclusion: A reduction in the anticholinergic burden from admission to discharge was observed in the study population yet, one-third of the study cohort were discharged with high anticholinergic medicines. Enhancing hospital prescribers' and pharmacists' awareness about anticholinergic burden and targeted interventions such as in-hospital deprescribing are needed to reduce high anticholinergic exposure in acute setting.