Cumulative Anticholinergic Burden and its Predictors among Older Adults with Alzheimer's Disease Initiating Cholinesterase Inhibitors

Background Cumulative anticholinergic burden refers to the cumulative effect of multiple medications with anticholinergic properties. However, concomitant use of cholinesterase inhibitors (ChEIs) and anticholinergic burden can nullify the benefit of the treatment and worsen Alzheimer's disease (AD). A literature gap exists regarding the extent of the cumulative anticholinergic burden and associated risk factors in AD. Therefore, this study evaluated the prevalence and predictors of cumulative anticholinergic burden among patients with AD initiating ChEIs. Methods A retrospective longitudinal cohort study was conducted using the Medicare claims data involving parts A, B, and D from 2013 to 2017. The study sample included older adults (65 years and older) diagnosed with AD and initiating ChEIs (donepezil, rivastigmine, or galantamine). The cumulative anticholinergic burden was calculated based on the Anticholinergic Cognitive Burden scale and patient-specific dosing using the defined daily dose over the 1 year follow-up period after ChEI initiation. Incremental anticholinergic burden levels were dichotomized into moderate-high (sum of standardized daily anticholinergic exposure over a year (TSDD) score >= 90) versus low-no (score 0-89). The Andersen Behavioral Model was used as the conceptual framework for selecting the predictors under the predisposing, enabling, and need categories. A multivariable logistic regression model was used to evaluate the predictors of high-moderate versus low-no cumulative anticholinergic burden. A multinomial logistic regression model was also used to determine the factors associated with patients having moderate and high burdens compared to low/no burdens. Results The study included 222,064 older adults with AD with incident ChEI use (mean age 82.24 +/- 7.29, 68.9% females, 83.6% White). Overall, 80.48% had some anticholinergic burden during the follow-up, with 36.26% patients with moderate (TSDD scores 90-499), followed by 24.76% high (TSDD score > 500), and 19.46% with low (TSDD score 1-89) burden categories. Predisposing factors such as age; African American, Asian, or Hispanic race; and need factors included comorbidities such as dyslipidemia, syncope, delirium, fracture, pneumonia, epilepsy, and claims-based frailty index were less likely to be associated with the moderate-high anticholinergic burden. The factors that increased the odds of moderate-high burden were predisposing factors such as female sex; enabling factors such as dual eligibility and diagnosis year; and need factors such as baseline burden, behavioral and psychological symptoms of dementia, depression, insomnia, urinary incontinence, irritable bowel syndrome, anxiety, muscle spasm, gastroesophageal reflux disease, heart failure, and dysrhythmia. Most of these findings remained consistent with multinomial logistic regression. Conclusion Four out of five older adults with AD had some level of anticholinergic burden, with over 60% having moderate-high anticholinergic burden. Several predisposing, enabling, and need factors were associated with the cumulative anticholinergic burden. The study findings suggest a critical need to minimize the cumulative anticholinergic burden to improve AD care.