Over 100,000 VHA patients receive anticoagulants (blood thinners) each year to prevent blood clots (including strokes). Too much anticoagulation increases the risk of serious or even fatal bleeding, and too little anticoagulation fails to protect the patient against blood clots. VHA anticoagulation clinics vary widely on how much time their patients spend in the therapeutic range, the range within which they are protected from clots but not at excessive risk of bleeding. Anticoagulation clinics can improve anticoagulation control by following several relatively simple procedures, including following-up promptly when patients are out of range and focusing on educating and supporting patients with poor control. In this study, the investigators will promote these practices at the anticoagulation clinics of the New England VA region, with a goal of improving anticoagulation control.

Background: Over 100,000 VA patients receive oral anticoagulation (AC) each year to prevent blood clots, including strokes. AC is safer and more effective when it is managed skillfully and therefore well-controlled. AC control can be measured using percent time in therapeutic range (TTR), the proportion of time when patients are sufficiently anticoagulated to prevent clots but not excessively anticoagulated (which increases the risk of bleeding). The investigators have shown that the anticoagulation clinics (ACCs) of the VA vary widely on TTR, from 40% (very poor control) to 70% (excellent control). Improving TTR in the VA would prevent thousands of adverse events, including strokes, major hemorrhages, and deaths. The investigators have further investigated the structures and processes of care that contribute to these wide disparities in TTR performance.

Objectives: We applied proven methods to change provider behavior. The goal was to facilitate the adoption of these evidence-based practices in order to improve TTR in VISN 1. We utilized educational outreach, audit and feedback, internal facilitation, and external facilitation to promote improvements in three evidence-based processes of care; namely, follow-up within 7 days after deranged INR values, minimizing loss to follow-up, and use of guideline concordant INR targets.

Methods: Our clinician-focused intervention used a Dashboard to measure site-level TTR and processes of care and an Algorithm for routine AC management. Both the Dashboard and the Algorithm are concrete representations of our main evidence-based recommendations to improve AC management. We promoted their use through quarterly visits to the sites, at which we delivered audit and feedback and educational outreach, and also provided external facilitation to address ways to improve these performance measures. Our main outcome was change in site TTR over time, which was compared between VISN 1 and non-VISN 1 sites using an interrupted time series. Secondary outcomes included site-level changes in processes of anticoagulation care (measured using automated data). We used a difference-in-differences (DID) model to examine changes in anticoagulation control, measured as percent time in target range (TTR), as well as process measures, and compared VISN 1 sites to 116 VA sites located outside VISN 1. The pre-intervention period was from 5/1/10-5/1/13, while the post-intervention period was from 5/2/13-5/10/16.

Inclusion Criteria:

• All patients receiving long-term oral anticoagulation with warfarin within the VA New England Region ("VISN 1")

Exclusion Criteria:

• Patients with valvular heart disease, who may have an INR target range other than 2-3. This usually represents between 10-15% of patients receiving anticoagulation.

Analysis was conducted at the site level and not the patient level.

Adverse events were not monitored or assessed.