Abstract 19108: Anticoagulation Treatment in High-Risk Medicare Advantage Patients with Non-Valvular Atrial Fibrillation

Abstract

OBJECTIVE: Examine anticoagulation (AC) treatment in Medicare Advantage Prescription Drug (MAPD) plan members diagnosed with non-valvular atrial fibrillation (NVAF) and at high risk for stroke. METHODS: A retrospective analysis of claims data from a large US health plan was conducted. Patients with NVAF were identified between 1/1/2011 and 11/30/2013. Index date was based on NVAF diagnosis and patients were required to have ≥18 months of continuous enrollment: 6 months pre-index and 12 months post-index. Pre-index stroke risk was calculated using the CHADS 2 . Patients classified as high risk (CHADS 2 score ≥2) were included in the analysis. Post-index AC treatment options were warfarin and novel oral anticoagulants (NOACs), dabigatran, apixaban, rivaroxaban. The proportion of high-risk patients with time in therapeutic range (TTR)≥60% was calculated among those receiving warfarin with ≥2 INR values within a 3-month period. Adherence among high-risk patients receiving a NOAC or warfarin without available INR values was calculated using the proportion of days covered (PDC)≥80%. Risk for major bleeding was also calculated using the HASBLED score. Descriptive statistics were used to summarize AC treatment. FINDINGS: Of 93,864 patients with NVAF, 70,646 were identified as high risk for stroke. Among them, 36,601 (51.8%) were treated with an AC while 34,045 (48.1%) did not receive any AC treatment during post-index. Of those treated with an AC, 30,802 (84.2%) were treated with warfarin and 5,799 (15.8%) were treated with a NOAC. TTR was calculated for 7,034 (22.8%) of those receiving warfarin, of which 3,215 (45.7%) had a TTR≥60%. PDC≥80% was observed for 13,758 (57.9%) of the remaining warfarin users and 3,353 (58.7%) of NOAC users. A total of 64,191 (90.8%) patients had a HASBLED score ≥3. CONCLUSIONS: A large proportion of NVAF patients at high risk for stroke are untreated or potentially undertreated_as evidenced by the low TTR values and low adherence estimates observed here. These patients’ high risk levels for stroke and major bleeding necessitate optimal prophylactic treatment with AC and careful management. Further research with providers may identify potential causes for non-treatment and undertreatment with AC in high risk NVAF patients.