Determination of Factors that Impact Adherence to Warfarin in Patients with Stroke

Objective: Oral anticoagulants are the mainstay in the secondary prevention of stroke. Adherence to drug is an important issue in preventing stroke. The aim of this study was to determine the adherence of patients with stroke to warfarin (anticoagulant agent) and to investigate the factors that may impact adherence. Materials and Methods: This descriptive cross-sectional study was conducted on patients admitted to an outpatient neurology clinic of a tertiary hospital in Istanbul. A total of 99 patients with stroke who were under warfarin treatment for at least 6 months prior to the study were enrolled in the study. Patients were assessed in terms of sociodemographic characteristics, adherence to and knowledge regarding the drug, anxiety and depression, mental and functional state and quality of life using validated scales. Results: The mean adherence score of the patients was 3.3 +/- 1.1 (0-4). The reported adherence rates were nor considered as low in our sample given that 42% had poor knowledge. Significant negative correlations were determined between drug adherence and age, number of risk factors, and duration of anticoagulant use (r=0.39, r=-0.33, r=-0.52, p <0.001, respectively). The mean drug adherence scores were lower in patients who had experienced drug-related adverse effects compared with those that did not (p=0.018). Significant correlations were found between the adherence scale and all other variables (p<0.05). Multiple linear regression analysis revealed that drug adherence was predicted by experiencing adverse effects, knowledge regarding the drug, and depression. Conclusion: Knowledge regarding the use of warfarin was inadequate in our patients, whereas adherence was reported not to be inadequate. The most influential factors that may impact adherence were adverse effects, knowledge, and depression. Healthcare professionals should be aware of patients who have risk factors for non-adherence.