Medication adherence to direct oral anticoagulants: extent and impact of side effects

Aim Recent studies have shown that good adherence cannot be taken for granted for patients on direct anticoagulants (DOACs). In this cross-sectional study, adherence among DOAC users was investigated and associations between beliefs about medication, perceived side effects and adherence were investigated. Methods We included 100 randomly selected adult DOAC users visiting one of the two participating Dutch community pharmacies in the summer of 2020. The self-reported adherence (primary outcome) was assessed with the Medication Adherence Rating Scale-5 (MARS-5). Beliefs about DOACs were assessed with the Beliefs about Medicine Questionnaire Specific (BMQ-S) while side effects were assessed with a self-developed questionnaire based on the Lareb Intensive Monitoring (LIM) system. Results Of the participants, 9% reported non-adherence on the MARS-5 (score <24). Associations were found between non-adherence and both reported side effects and side effect burden. Furthermore patients’ belief that DOACs have unpleasant side effects was associated with both non-adherence and more side-effects. No associations were found between adherence and either gender, indication, DOAC or dosage. Conclusion This study confirms that non-adherence in patients on DOACs is prevalent. We recommend that both physicians and pharmacists evaluate adherence and side effects with their DOAC patients on a regular base.