Impact of drug utilization management strategies on the incidence and cost of clinical events in patients with non-valvular atrial fibrillation receiving DOACs in the US.

Aims: Medicare plans employ drug utilization management strategies, including prior authorization (PA) and step therapy (ST), or formulary tier increases, to control spending. However, PA and ST can delay treatment access and encourage use of less effective/safe therapies, while formulary tier increases can lead to treatment switching/discontinuation due to higher patient out-of-pocket costs. This study modeled the impact of restricted access to direct oral anticoagulants (DOACs), and a tier increase for apixaban, on incidence and cost of clinical events in patients with non-valvular atrial fibrillation (NVAF) in the US.

Materials and methods: Decision models were developed using hypothetical cohorts of 1,000,000 Medicare Fee-For-Service plan members to evaluate incidence and cost of clinical events of two utilization management strategies over one-year. Model 1 compared restricted access (PA or ST required) versus unrestricted access to DOACs; model 2 compared a formulary tier increase for apixaban (patients assumed to continue apixaban, switch (to any DOAC (primary analysis) or rivaroxaban (secondary analysis)), or discontinue at rates of 57.5%, 12.4%, and 30.1%, respectively) versus no tier increase (patients assumed to continue apixaban). Epidemiology, clinical, and cost inputs were sourced from literature and online databases and costs inflated to 2024 US dollars.

Results: In the "restricted access" cohort (model 1; n = 67,984) patients experienced an additional 57 strokes, 61 major bleeds (MBs), 43 transient ischemic attacks, and 452 all-cause deaths versus the "unrestricted access" cohort, accruing additional annual costs of $8,008,860. A tier increase for apixaban (model 2; n = 47,036) resulted in an additional 330 (secondary analysis: 257) stroke/systemic embolisms, 58 (20) MBs and 32 (25) deaths versus the "no tier increase" cohort, costing an additional $6,542,373 ($4,656,305) annually.

Conclusions: For patients with NVAF, PA/ST restrictions for DOACs and a formulary tier increase for apixaban resulted in additional clinical events and higher clinical event-related costs for US Medicare payers.