1059 — Effect of Dual Use of Veterans Affairs (VA) and Medicare Part D Drug Benefits on Chronic Disease Refill Adherence in Veterans with Dementia

Lead/Presenter: Carolyn Thorpe, COIN - Pittsburgh/Philadelphia
All Authors: Thorpe CT (VA Pittsburgh Healthcare System) Thorpe JM (VA Pittsburgh Healthcare System) Gellad WF (VA Pittsburgh Healthcare System) Mor MK (VA Pittsburgh Healthcare System) Pleis JR (VA Pittsburgh Healthcare System) Van Houtven CH (Durham VA Medical Center) Schleiden LJ (VA Pittsburgh Healthcare System) Hanlon JT (VA Pittsburgh Healthcare System) Niznik JD (VA Pittsburgh Healthcare System) Good CB (VA Pittsburgh Healthcare System)

Objectives:
We evaluated the effect of dual use of VA/Medicare Part D drug benefits on adherence to antihypertensive (AH) and oral antidiabetic (OAD) medications in Veterans with dementia, who may be especially vulnerable to care fragmentation and medication nonadherence.

Methods:
We analyzed 2007-2010 VA utilization and medication data linked to Medicare claims and Part D records for VHA enrollees with dementia aged >=68 years also enrolled in fee-for-service Medicare. We identified patients obtaining AH medications through VA or Part D (n = 58,242) and classified them as VA-only, Part D-only, or dual VA/Part D users, based on where they filled AH prescriptions in 2010. We calculated 2010 medication possession ratios (MPRs) for each AH class that patients obtained in late 2009 and categorized MPRs as undersupply ( < 80%), appropriate supply (>=80% to < 120%), or oversupply (>=120%). We used propensity score-weighted logistic regression to examine the association of user group with undersupply of any AH class vs. appropriate supply of all classes, and oversupply of any class vs. appropriate supply of all classes. We also identified patients using OAD medications (n = 15,363) and used similar methods to examine the association of dual OAD use and OAD adherence.

Results:
In unadjusted analyses, 48% of dual AH users had undersupply of at least one class, versus 44% of VA-only and 51% of Part D-only users; 31% of dual AH users had oversupply of at least one class, versus 12% of VA-only users and 10% of Part D-only users. Propensity score-weighted models revealed that dual users were more likely than VA-only users to have any undersupply (OR = 1.32; 95% CI = 1.21,1.45) and any oversupply (OR = 2.20; 95% CI = 2.01,2.39), vs. appropriate supply of all classes. Part D-only users were more likely to have any undersupply, but less likely to have any oversupply. Analyses of OAD adherence yielded similar results.

Implications:
Obtaining antihypertensive and antidiabetic medications through both VA and Part D instead of VA-only increased odds of undersupply and oversupply of medications in VA patients with dementia

Impacts:
Increased efforts by VA and CMS to coordinate medications across systems of care may be needed to reduce nonadherence associated with dual use of VA and Medicare drug benefits.