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Association of Out-of-pocket Costs on Adherence to Common Neurologic Medications (306679)
*Evan Lee Reynolds, University of MichiganKeywords: health services research, insurance claims data, neurology, medication adherence, instrumental variable analysis
To determine the association between out-of-pocket costs and medication adherence in 3 common neurologic diseases we utilized privately-insured claims from 2001-2016. We identified patients with incident neuropathy, dementia, or Parkinson disease and selected patients who were prescribed medications with similar efficacy and tolerability, but differential out-of-pocket costs. Instrumental variable analysis and negative binomial regression was used to estimate the association of out-of-pocket costs and other patient factors on medication adherence. We identified 52,249 patients with neuropathy on gabapentinoids, 5,246 patients with neuropathy on SNRIs, 19,820 patients with dementia on cholinesterase inhibitors, and 3,130 patients with Parkinson on dopamine agonists. Increasing out-of-pockets costs by $50 was associated with significantly lower medication adherence for patients with neuropathy on gabapentinoids (adjusted IRR: 0.91, 0.89-0.93) and dementia (adjusted IRR: 0.88, 0.86-0.91). Minority populations had lower adherence for gabapentinoids and cholinesterase inhibitors compared to White patients.