Key result
DOAC adherence thresholds near ~80% proportion of days covered preserve stroke prevention efficacy.
Why the study?
It remained an open question what defines good adherence to DOACs or below which threshold non-adherence becomes clinically relevant for stroke prevention in AF patients.
What is the minimum adherence threshold (proportion of days covered) required for effective stroke prevention with rivaroxaban and apixaban in patients with atrial fibrillation, and how do targeted versus untargeted adherence interventions impact stroke occurrence and costs?
Cohort (n=10,092)
What is the minimum adherence threshold (proportion of days covered) required for effective stroke prevention with rivaroxaban and apixaban in patients with atrial fibrillation, and how do targeted versus untargeted adherence interventions impact stroke occurrence and costs?
Empirically derived DOAC adherence thresholds of 0.78 for rivaroxaban and 0.80 for apixaban validate the conventional 80% adherence benchmark and show that targeting adherence interventions to patients below these cut-offs is substantially more effective and cost-saving than untargeted interventions.
Supports ~80% PDC thresholds for DOAC efficacy in AF; extends benchmarks but leaves open randomized validation of targeted interventions.
BACKGROUND: An essential contribution regarding the prevention of thromboembolic events in patients with (non-valvular) atrial fibrillation (AF) is good adherence to direct oral anticoagulants (DOACs). However, it is an open question what "good" adherence means for DOACs or below which threshold non-adherence is clinically relevant for AF patients. Ultimately, such a classification could prevent strokes and associated costs through adjusted treatment regimens or supportive measures. METHODS: We selected 10,092 AF patients from health insurance claims data between 2014 and 2018 who were issued a majority (at least half of the number) of maximum approved strength prescriptions of one of the following DOACs, namely rivaroxaban, apixaban, or dabigatran. Due to the limited sample size, the prescriptions of dabigatran had to be finally excluded for the cut-off analysis. DOAC adherence was calculated as the proportion of days covered (PDC) by dividing the days of theoretical use (days covered) of the drug by the duration in days of the observation interval. PDC cut-off values were derived from stroke risk as a function of continuous PDC values in time-to-event analyses and corresponding dose-response models. The influence of adherence-promoting interventions (targeted and untargeted) on the occurrence of strokes and related costs was then projected, considering intervention costs per patient. RESULTS: The population had a mean age of 74.5 years and 50% were female. The median PDC was 0.79 ± 0.28 with a median follow-up time of 1218 days, in which 2% of all DOAC patients had a stroke. The adherence cut-offs for good adherence were identified at 0.78 for rivaroxaban and 0.8 for apixaban. Targeted interventions appeared to be far more cost-effective than untargeted interventions. CONCLUSION: Clear adherence cut-offs enable healthcare professionals to identify patients with clinically relevant non-adherence. Interventions based on these cut-offs appear to be a promising means to optimize DOAC treatment.
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Wirbka et al. (2021) conducted a cohort in Non-valvular atrial fibrillation (n=10,092). Direct oral anticoagulant (DOAC) adherence (proportion of days covered [PDC] for rivaroxaban, apixaban, or dabigatran) vs. Lower adherence / continuous PDC levels and comparison between rivaroxaban and apixaban was evaluated on Stroke risk and derived minimum adherence cut-off (PDC) for 80% efficacy (ED80) (HR 1.05 per 10% adherence decrease (rivaroxaban); HR 1.03 per 10% adherence decrease (apixaban), 95% CI 0.98-1.12). DOAC adherence cut-offs for achieving 80% maximum stroke prevention efficacy were identified at a proportion of days covered of 0.78 for rivaroxaban and 0.80 for apixaban.
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