The relationship between knowledge, health literacy and adherence among patients taking oral anticoagulants for stroke thromboprophylaxis in atrial fibrillation

Background: Patients' knowledge regarding their oral anticoagulant (OAC) treatment for stroke prevention in atrial fibrillation (AF), their level of medication adherence and health literacy are known to affect treatment outcomes. However, contemporary data regarding the relationships between these variables are lacking.

Objective: To investigate the relationships between anticoagulant knowledge, health literacy and self-reported adherence in patients taking warfarin and the directly acting oral anticoagulants.

Methods: A cross-sectional survey was conducted in 48 patients with AF identified from general practices. The Anticoagulation Knowledge Tool (AKT) was used to assess anticoagulation knowledge; the Short Test of Functional Health Literacy in Adults (s-TOHFLA) for health literacy; and the 8-item Morisky Medication Adherence Scale (MMAS) for medication adherence.

Results: Participants had mean scores of 61.6 ± 15.8, 7.2 ± 1.1 and 24.7 ± 9.5 for the AKT, MMAS-8 and s-TOHFLA, respectively. Significant correlations were observed between anticoagulation knowledge and health literacy with medication adherence (0.37, p < 0.01 and 0.30, p < 0.05, respectively). Participants with inadequate health literacy had a significantly lower mean knowledge score than those with adequate health literacy (55.8 ± 15.9 vs 66.1 ± 14.4, p < 0.05). Participants who self-reported adherence to their OAC had significantly higher knowledge scores than those who did not (67.5 ± 13.3 vs 56.1 ± 16.2, p < 0.05).

Conclusion: Significant correlations between health literacy, OAC knowledge and adherence were observed, and these relationships should to be considered by health professionals responsible for monitoring patients who are prescribed anticoagulants. We also observed serious gaps in OAC knowledge. Interventions designed to optimize the outcomes of anticoagulant treatment need to address these factors.