Assessing theoretical predictors of long-term medication adherence: patients' treatment-related beliefs, experiential feedback and habit development.

Patient non-adherence to medication is a pervasive problem that contributes to poor patient health and high healthcare costs. Basic research and interventions have focused thus far on behaviour initiation factors, such as patients' illness and treatment beliefs. This paper proposes two processes that occur after behaviour initiation that are theorised to contribute to prediction of long-term medication adherence: 'coherence' of patients' beliefs from experiences with treatment and habit development. Seventy-one hypertensive patients reported their treatment-related beliefs, experiences related to treatment efficacy and medication-taking habit strength in a baseline interview. Patients then used an electronic monitoring pill bottle for approximately one month. Patients' medication habit-strength was the strongest predictor of all adherence measures, explaining 6-27% incremental variance in adherence to that explained by patients' treatment-related beliefs. Patients' beliefs and experiences did not predict overall adherence, even for patients with 'weaker' habits. However, patients' experiences were found to predict intentional non-adherence and habit strength was found to predict unintentional adherence. Practitioners may assess patients' medication-taking habits to get an initial view of their likely adherence to long-term medications. Future research should assess the current theoretical predictions in a hypertension inception sample and in populations with symptomatic conditions.