Nearly half of Medicare beneficiaries with Parkinson’s disease were concurrently prescribed a high-potency anticholinergic medication and an acetylcholinesterase inhibitor, with higher rates of potential prescribing errors seen among women and Hispanic patients, according to a cross-sectional analysis of Centers for Medicare & Medicaid Services data published in JAMA Neurology.

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“Coadministration of a drug with high anticholinergic activity and an [acetylcholinesterase inhibitor] represents a frank prescribing error because these drugs have opposing pharmacologic effects,” wrote Sneha Mantri, MD, of the Parkinson’s Disease Research, Education, and Clinical Center at the Philadelphia VA Medical Center, and her colleagues. “In patients with Parkinson disease, who bear additional risks of cognitive impairment and vulnerability to anticholinergic activity, coprescribing of an [acetylcholinesterase inhibitor] and a high-potency anticholinergic medication can be considered a never event because it is a medication error likely to contribute to disability.”

Dr. Mantri and her colleagues analyzed the inpatient, outpatient, and prescription data of 268,407 Medicare beneficiaries with Parkinson’s, of whom 73,093 patients (27.2%) were prescribed a minimum of one antidementia medication fill. Patients were mean 78.9 years old, and the demographics of the Medicare beneficiaries were 50.1% male, 86.7% white, 5.5% black, 2.7% Hispanic, 2.7% Asian, and 0.7% Native American. The most common antidementia prescriptions were donepezil hydrochloride (63.0%), memantine hydrochloride (41.8%), and rivastigmine tartrate (26.4%). The researchers measured medications in cases of coprescription with potential anticholinergic (ACH) activity using the Anticholinergic Cognitive Burden Scale.

They found antidementia medication use was associated with patients who were black (adjusted odds ratio, 1.33; 95% confidence interval, 1.28-1.38) and Hispanic (aOR, 1.28; 95% CI, 1.22-1.35). Meanwhile, a negative association was found between Native American patients and antidementia medication use (aOR, 0.62; 95% CI, 0.51-0.74) compared with white patients and women (aOR, 0.85; 95% CI, 0.84-0.87) compared with men. The researchers noted that 28,495 patients (44.5%) were prescribed concurrently one high-potency anticholinergic and acetylcholinesterase inhibitors, with higher rates of prescribing seen for Hispanic (aOR, 1.11; 95% CI, 1.00-1.23) and women (aOR, 1.30; 95% CI, 1.25-1.35). High prevalence clusters of this type of prescribing were statistically high in the Southern and Midwestern states, they added.

Limitations included the study of a single year of data and the absence of conclusive data of dementia prevalence among Parkinson’s patients based on antidementia medication use alone and potential off-label use of antidementia medication analyzed in the study, the researchers said.

“In determining whether anticholinergic drug exposure has a causal role in clinical dementia in Parkinson disease, future studies may take a clinical trial approach, in which high-potency anticholinergic medications are replaced with lower-potency alternatives, and the change in cognitive testing and cognitive trajectory are measured,” Dr. Mantri and her colleagues wrote. “Such an approach will allow the calculation of anticholinergic drug safety in terms that are easily understood, such as number needed to harm.”

This study was funded by a grant from the National Institute of Neurological Diseases and Stroke of the National Institutes of Health. The authors report no relevant conflicts of interest.

SOURCE: Mantri S et al. JAMA Neurol. 2018 Oct 1. doi: 10.1001/jamaneurol.2018.2820.