Dr Brian CallaghanBrian C. Callaghan, MD, MS
New study results published in Neurology suggest that lower medication adherence is associated with higher out of pocket costs for patients with incident neuropathy, dementia, or Parkinson disease.1,2

Conducted by Brian C. Callaghan, MD, MS, the Fovette E. Dush Early Career Professor of Neurology, University of Michigan Medicine, and colleagues, the findings confirm that physicians should consider these costs when prescribing treatments in these diseases as a way to improve adherence. This, the authors noted, is of considerable importance as out of pocket costs continue to rise in the US.

“These results are concerning, especially as we’ve seen the cost of prescription drugs continue to rise and an increasing amount of the cost being shifted to patients through out-of-pocket costs,” Callaghan said in a statement. “Of course, if people do not follow their prescriptions correctly, they are less likely to benefit from the drug and see improvements in their condition, possibly leading to complications and higher costs later.”

They noted that they also observed racial/ethnic disparities, enough so to indicate additional focus in minority populations for future intervention efforts to improve adherence. “New approaches to increase medication adherence for these population groups is critically important to reducing health care disparities,” Callaghan said.
 
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All told, an increase of just $50 in out of pocket costs for a 30-day supply was associated with a significant 9% drop in medication adherence for those with neuropathy on gabapentinoids (adjusted incidence rate ratio [IRR], 0.91; 95% CI, 0.89–0.93) and a 12% drop for those with dementia (adjusted IRR, 0.88; 95% CI, 0.86–0.91).

In 2015, the cost of donepezil was ~$3 for a 30-day supply, people filled their prescriptions about 70% of the time, compared to rivastigmine, which cost ~$100 for a 30-day supply at that time—for which people filled their prescriptions about 45% of the time.

On the other hand, increased out of pocket costs were not significantly associated with medication adherence for individuals with neuropathy on SNRIs (adjusted IRR, 0.97; 95% CI, 0.88–1.08) and those with Parkinson disease (adjusted IRR, 0.90; 95% CI. 0.81–1.00).

As those with Alzheimer dementia and neuropathy often have several comorbidities and require additional medications, Callaghan and colleagues noted that the effect of out of pocket drug costs may be magnified for those patients.

“Out of pocket costs have risen to the point where systematic changes are needed,” said James C. Stevens, MD, FAAN, President American Academy of Neurology (AAN), in a statement. “These changes could include legislative action to place a cap on out of pocket costs, which the AAN is advocating for in Washington, D.C. Another change could be to provide neurologists with access to information on drugs costs so that when they meet with patients to make treatment decisions, they can help to minimize the financial burden.”

The dataset included privately insured claims from 2001 to 2016 for 52,249 patients with neuropathy who were on gabapentinoids; 5246 patients with neuropathy on mixed serotonin/norepinephrine reuptake inhibitors (SNRIs); 19,820 patients with dementia on cholinesterase inhibitors; and 3130 patients with Parkinson on dopamine agonists.

Callaghan and colleagues defined medication adherence as the number of days supplied in the first 6 months and used instrumental variable analysis to estimate the link between out of pocket costs and other patient factors on medication adherence. They chose individuals prescribed medications with similar efficacy and tolerability, but differential out of pocket costs, which landed them with the aforementioned medications.

The average out of pocket cost in 2016 for a 30-day supply of rivastigmine was $79.30 compared to $3.10 for the drug donepezil. For pregabalin, the cost was $65.70 compared to $8.40 for gabapentin. Additionally, the drug pramipexole cost $35.90 compared to $12.40 for the drug ropinirole.

They noted that a limitation of the work was the inability to measure the number of people who never filled their first prescription, which might be related to out of pocket costs. Additionally, they only looked at those with private insurance, so the results may not apply to other patient populations.
REFERENCES
1. Reynolds EL, Burke JF, Banerjee M, et al. Association of out-of-pocket costs on adherence to common neurologic medications. Neurology. 2020;94:1–12. doi: 10.1212/WNL.0000000000009039.
2. As Out-of-Pocket Costs for Neurologic Medications Rise, People Less Likely to Take Them [press release]. Minneapolis, MN: American Academy of Neurology; Published February 19, 2020. Accessed February 20, 2020.