Generic initiation and antidepressant therapy adherence under Medicare Part D

Area of Science:

• Health Services Research
• Pharmacoeconomics
• Geriatric Medicine

Background:

• Antidepressant therapy adherence is crucial for managing depression effectively.
• The Medicare Part D coverage gap can pose a barrier to consistent medication access and adherence.
• Understanding factors influencing adherence is vital for optimizing patient outcomes.

Purpose of the Study:

• To evaluate the impact of starting antidepressant treatment with a generic prescription on patient adherence.
• To determine if the Medicare Part D coverage gap modifies the effect of generic initiation on adherence.

Main Methods:

• A 5% random sample of Medicare fee-for-service beneficiaries diagnosed with depression in 2007 was analyzed (n=16,778).
• Adherence was measured by antidepressant possession gaps and monthly days of possession over 180 days.
• Cox proportional hazard and mixed-effects linear models were used, stratified by Low-Income Subsidy (LIS) status and Medicare entitlement.

Main Results:

• Generic antidepressant initiation was linked to improved adherence across all patient groups.
• The positive effect of generic initiation was more pronounced in non-LIS patients.
• Generic initiation increased monthly possession days and offered additional benefits during the coverage gap for non-LIS patients.

Conclusions:

• Starting antidepressant therapy with generic prescriptions can significantly enhance adherence among Medicare patients.
• Generic initiation serves as a valuable strategy to overcome adherence challenges, particularly those exacerbated by the Medicare Part D coverage gap.