Knowledge of and attitudes towards depression and adherence to treatment: The Antidepressant Adherence Scale (AAS)

Background: Non-adherence to treatment can result from forgetting, carelessness, stopping the drug when feeling worse, or stopping the drug when feeling better. Objective: To develop and psychometrically assess a brief instrument that can be easily used in clinical practice to measure adherence to antidepressants. Method: We developed the Antidepressants Adherence Scale (AAS); a self report rating scale including four items to assess the degree to which forgetting, carelessness, and stopping due to feeling worse or feeling better interfere with adherence in the last 4 weeks. Our proposed four-item adherence instrument was developed based on previous research and theory. Participants: Experts in mood disorders (n = 12) participated in the formal validity assessment of the instrument, and the developed instrument was administered to patients who were prescribed antidepressants (n = 63). All patients also completed a multiple choice question instrument to measure knowledge of depression, and a Likert self report questionnaire to assess attitudes towards depression and its treatment. Results: There was 90% agreement among experts that the items were highly relevant providing strong evidence for content validity. Also, there was empirical evidence for validity. There were significant correlations (p < 0.05) between knowledge and attitude subscales and adherence items. The internal consistency reliability (Cronbach's alpha) was 0.66 for the instrument Conclusion and significance: Knowledge of and attitudes to depression and its treatment may have significant impact on the adherence to antidepressants. The AAS can be used in clinical settings (2-3 min to administer) to evaluate patients' adherence to antidepressants.