Anticoagulation Control in Swiss Primary Care: Time in Therapeutic Range Percentages Exceed Benchmarks of Phase III Trials

Abstract

Background: In randomized controlled trials, non-vitamin K antagonist oral anticoagulants (NOACs) demonstrated noninferiority to vitamin K antagonists (VKAs) in patients who spent limited time in therapeutic range (TTR). In real-life patients, TTR is known to vary significantly across countries and health-care settings. Objective: We aim to evaluate the quality of VKA treatment in Swiss primary care (PC) by comparing patients’ median TTR to levels achieved in the phase III NOAC trials RE-LY, ROCKET-AF, ARISTOTLE, and ENGAGE-AF-TIMI 48. Patient characteristics affecting TTR control shall be estimated. Methods: This is a retrospective longitudinal study in Swiss PC patients receiving VKA for ≥6 months. We identified patients from the PC research database FIRE (Family medicine International Classification of Primary Care Research using Electronic medical records) and calculated TTR according to Rosendaal formula. Comparative data from NOAC trials were retrieved from medical literature. Linear regression models were used to assess predictors of TTR. Results: Primary care encounters of 215 patients were analyzed. Like in the NOAC trials, median observation period was 2.2 years, but patients were older (67.9% vs 38% ≥75 years) and differed in terms of concomitant diseases and drugs. Median TTR was 75% (65% in the NOAC trials). Female sex was independently associated with a lower TTR and significantly modified by increasing age. Conclusion: Practitioners should consider that patients in NOAC trials are only partly representative of PC patients, particularly in terms of TTR control. Only a minority of the observed patients would require a therapy switch to NOACs due to inadequate TTR. Further research is needed in order to identify specific features of care management that are associated with these outcomes.