PURPOSE:
To assess the impact of International Normalized Ratio (INR) self testing and online remote monitoring and management (STORM2) on clinical events and costs vs. traditional warfarin management and the new oral anticoagulants (NOACs) in atrial fibrillation (AF).
METHODS:
Seven STORM2 trials had a weighted mean INR time in the target range (TTR) of 77.2%. Thromboembolism (TE) and major bleeding (MB) rates at 30%, 45%, 55%, 65%, and 75% TTR were calculated using linear regression equations from a systematic review of 38 AF studies. MB = 10.104 - 0.120x[TTR], (p = 0.004) and TE = 8.313 - 0.098x[TTR], (p = 0.03). MB and TE rates were sub-divided based on the distribution in the NOAC trials. TTR-based mortality was calculated based on a 6%/yr rate multiplied by the adjusted relative risks from a data base analysis of approximately 38,000 AF patients. Projected event rates at 75% TTR, expressed as number per 1,000 patient-years, were compared to event rates at lower TTR ranges and to rates reported in the NOAC trials. Differences in major event rates were used to calculate cost avoidance.
RESULTS:
Projected event rates with STORM2 (TTR of 75%) when compared to “conventional ” TTR of 55% to 65% were 64% to 71% lower for MB, 47% to 64% lower for TE, and 47% to 57% lower for mortality. Compared to the NOAC study results, the projected rates were 48% to 70% lower for MB, 41% to 66% lower for TE, and 40% to 53% lower for mortality. Projected cost avoidance was $10.4 million vs. a TTR of < 30%, $2.2 million vs. a TTR of 65%; and from $1.4 to $3.1 million vs the NOACs. Costs of “other” MB and TE , drug costs, and monitoring costs were not included in the estimates.
CONCLUSIONS:
STORM2 management of warfarin is projected to produce a 50% or greater reduction in major event rates with a cost avoidance of $1.4 to $10.4 million per 1,000 patients per year.
CLINICAL IMPLICATIONS:
STORM2 management may transform the safety and efficacy of anticoagulation for the millions of people with AF while substantially reducing costs. These findings warrant randomized, prospective trials in AF and other indications for anticoagulation.
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