Non–adherence to aspirin or oral anticoagulants in secondary prevention after ischaemic stroke

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Abstract
Background The effectiveness of medication is influenced by treatment adherence. After TIA or minor disabling stroke patients usually are advised to take antithrombotic medication. Stroke patients are an interesting group of patients with respect to adherence, since cardiovascular risk factors and stroke may (indirectly) negatively influence brain function, which can affect adherence. We investigated determinants of non–adherence in patients who used aspirin or oral anticoagulation after cerebral ischaemia of arterial origin. Methods Data of patients prospectively followed in two clinical trials (the Dutch TIA Trial and the Stroke Prevention In Reversible Ischaemia Trial) were analysed with Cox proportional hazards modelling. Results In the two trials 3796 patients were treated with aspirin. During a mean follow–up of 2.1 years, 689 patients (18%) prematurely stopped treatment, 305 (8 %) did so without a clear medical reason (non–adherence). Age ≥ 65 years and the use of 300 instead of 30 mg of aspirin were independently associated with non–adherence. Diastolic blood pressure of ≥ 90 mmHg and dizziness were associated with better adherence. Of 651 patients on oral anticoagulation, 143 patients (22 %) stopped after a mean follow–up of 1.0 year, 66 (10 %) did so because of nonadherence. No statistically significant determinants for non–adherence were identified. Conclusion As found in the literature on nonadherence in general, age of ≥ 65 years and a higher dose of aspirin (300 mg versus 30 mg) were independently associated with non–adherence with aspirin treatment that was prescribed for secondary prevention after cerebral ischaemia of arterial origin. Older patients may require extra encouragement to continue antithrombotic treatment. Lower doses of aspirin may improve treatment adherence.