US Study Shows Patterns of Prescription Errors for Dementia Therapies to Parkinson’s Patients

Women and Hispanic patients with Parkinson’s disease, as well as those living in Southern and Midwestern U.S. states, are most often prescribed inappropriate dementia therapies, a nationwide study reveals.

The study, “Patterns of Dementia Treatment and Frank Prescribing Errors in Older Adults With Parkinson Disease,” appeared in the journal JAMA Neurology.

Cognitive impairment in Parkinson’s patients is a major reason behind their loss of independence, as well as nursing home placement and healthcare costs. About 1 in 4 Parkinson’s patients has objective cognitive impairment at the time of diagnosis, and dementia affects about 80-90% of patients by 12 years after diagnosis.

Despite the high incidence of cognitive impairment in Parkinson’s patients, there is little information on dementia medication use.

University of Pennsylvania researchers reviewed the clinical records of 268,407 Medicare beneficiaries with a Parkinson’s diagnosis who had 12 consecutive months of inpatient, outpatient, and prescription medicine coverage from January to December 2014. Medicare is the primary insurer for 97 percent of the U.S. population ages 65 years or older.

According to Medicare Services data, about 27.2% of the Parkinson’s patients included in the study had filled at least one prescription for a dementia medication in 2014. The most commonly prescribed therapy was Aricept (donepezil), followed by Namenda (memantine) and Exelon (rivastigmine), while Razadyne (galantamine) use was uncommon.

Women were found to be 15% less likely to use dementia medication than men. Black patients were 38% more likely and Hispanic patients 28% more likely to use these therapies than white patients, while Native Americans were about 38% less likely.

“Female sex was associated with lower odds of dementia medication use … Dementia medication use was positively associated with black and Hispanic race/ethnicity, and it was negatively associated with Native American,” the researchers wrote.

Use of a dementia medicine was associated with a dementia diagnosis, but also depression, hip or pelvic fracture, and stroke or transient ischemic attack.

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Approximately 66.4% of patients were only prescribed a single dementia medicine during the year, while 26.7% had prescription fills for both Namenda and an acetylcholinesterase inhibitor (AChEI), most frequently Aricept or Exelon.

“Coadministration of a drug with high anticholinergic activity [such as Namenda] and an AChEI represents a frank prescribing error because these drugs have opposing pharmacologic effects,” the researchers wrote.

“In patients with Parkinson disease, who bear additional risks of cognitive impairment and vulnerability to anticholinergic activity, coprescribing of an ACHEI and a high-potency anticholinergic medication can be considered a never event because it is a medication error likely to contribute to disability,” they said.

Almost 45% of Medicare beneficiaries with Parkinson’s and a clinical diagnosis of dementia filled a prescription for a medication that could further worsen their cognitive impairment over the course of a single year.

The records revealed that black beneficiaries were 17% less likely to be prescribed both a high-potency anticholinergic agent and AChEI than white Parkinson’s patients. In contrast, Hispanics and women had an 11% and 30% increased chance of experiencing this so-called never event, defined as a serious medical error or occurrence that should never happen to a patient and can cause harm.

Dual prescriptions of an anticholinergic agent and AChEI were found to be more frequent among patients with secondary conditions, including depression, chronic obstructive pulmonary disease (COPD), hypertension, chronic kidney disease, diabetes, and heart failure.

Clusters of high prevalence of inappropriate prescribing were found in the Southern and Midwestern U.S. regions, while clusters of low prevalence of inappropriate dual-prescribing were reported in the Northwest and Northeast.

“We identified unique patterns of dementia medication use among individuals with Parkinson disease, along with racial/ethnic, sex, and geographic disparities in potentially inappropriate prescribing habits,” the researchers said.

Further studies are warranted to explore the potential contributing role of anticholinergic agents in the development of dementia among Parkinson’s patients.

“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,” the researchers suggested.

Additionally, improvements in practitioner education may “lessen negative patient outcomes in the future,” they added.