Warfarin time in therapeutic range and its impact on healthcare resource utilization and costs among patients with nonvalvular atrial fibrillation

Abstract

Background:

Warfarin is efficacious for reducing stroke risk among patients with nonvalvular atrial fibrillation (NVAF). However, the efficacy and safety of warfarin are influenced by its time in therapeutic range (TTR).

Objective:

To assess differences in healthcare resource utilization and costs among NVAF patients with low (<60%) and high (≥60%) warfarin TTRs in an integrated delivery network (IDN) setting.

Methods:

Patients with NVAF were identified from an electronic medical record database. Patients were required to have ≥6 international normalized prothrombin time ratio (INR) tests. NVAF patients were grouped into two cohorts: those with warfarin TTR <60% (low TTR) and those with warfarin TTR ≥60% (high TTR). Healthcare resource utilization and costs were evaluated during a 12 month follow-up period. Multivariable regressions were used to assess the impact of different warfarin TTRs on healthcare costs.

Results:

Among the study population, greater than half (54%, n = 1595) had a low TTR, and 46% (n = 1356) had a high TTR. Total all-cause healthcare resource utilization was higher among patients in the low TTR cohort vs. the high TTR cohort (number of encounters: 70.2 vs. 56.1, p < 0.001). After adjusting for patient characteristics, total all-cause healthcare costs and stroke-related healthcare costs were $2398 (p < 0.001) and $687 (p = 0.02) higher, respectively, for patients in the low TTR cohort vs. the high TTR cohort.

Limitations:

In this retrospective study, we were only able to evaluate the association and not the causality between healthcare resource utilization and costs with the different warfarin TTRs.

Conclusion:

Many warfarin-treated NVAF patients have a low warfarin TTR. NVAF patients with low vs. patients with high warfarin TTR used healthcare resources to a greater extent, which was reflected in higher healthcare costs.

Keywords: :

• Costs
• Healthcare systems
• International normalized ratio
• Nonvalvular atrial fibrillation
• Warfarin

Transparency

Declaration of funding

Sponsorship of this study was provided by Bristol-Myers Squibb and Pfizer.

Declaration of financial/other relationships

S.D. has disclosed that he is a consultant for Bristol-Myers Squibb and Pfizer. M.E. has disclosed that he is a consultant to MedMining which received funding from Bristol-Myers Squibb and Pfizer in connection with conducting this study. E.H. has disclosed that he was an employee of Bristol-Myers Squibb at the time of the study. A.B. has disclosed that she is an employee of Bristol-Myers Squibb and owns stock in the company. J.T. and W.T. have disclosed that they are employees of Pfizer and own stock in the company. P.S. has disclosed that she is an employee of Bristol-Myers Squibb. J.L. and M.L.-S. have disclosed that they are employees of Novosys Health, which has received research funds from Bristol-Myers Squibb and Pfizer in connection with conducting this study.

CMRO peer reviewer 1 has disclosed that he is a consultant to Daiichi Sankyo. CMRO peer reviewer 2 has no relevant financial or other relationships to disclose.