Guideline‐concordant initiation of oral anticoagulant therapy for stroke prevention in older veterans with atrial fibrillation eligible for Medicare Part D

Objective

To characterize the rate of guideline‐concordant initiation of oral anticoagulation (OAC) among elderly Veterans with atrial fibrillation (AF) and high stroke risk.

Data Sources/Study Setting

Veterans Health Administration (VHA) Corporate Data Warehouse (CDW) linked with Medicare claims 2011‐2015.

Study Design

We identified 6619 elderly, high stroke‐risk patients with a new episode of AF initially diagnosed in the VHA during fiscal years 2012‐2015. We used logistic regression to estimate marginal effects of associations between patient characteristics and OAC initiation within 90 days of the first AF episode.

Data Extraction Methods

We identified OACs using generic drug names. We calculated comorbidities and risk scores using diagnosis codes from 1 year of baseline data.

Principal Findings

Overall, 66.5% of Medicare‐eligible Veterans with AF at high risk of stroke initiated an OAC within 90 days. We found lower initiation rates for patients enrolled in Medicare Part D and those ineligible for drug co‐payment subsidies. OAC initiation rates increased during the study among VHA‐reliant patients but not among dual VHA‐Part D enrollees.

Conclusions

One‐third of elderly Veterans at risk of stroke are not receiving recommended therapy. Increased coordination between Medicare and VHA providers may lead to improvements in anticoagulation quality and stroke prevention.