A review of published studies of patients' illness perceptions and medication adherence: lessons learned and future directions.

Background: Patients who seek medical care and who are prescribed medication may choose to either accept or not accept the prescriber's recommendations to use the prescribed medication. The Common Sense Model (CSM) is one behavioral model that can help researchers and practitioners to identify patients' illness perceptions that drive their decisions.

Objective: This article reviews published research that evaluated the impact of illness representations (as defined in CSM) with medication adherence.

Methods: A narrative review of published research in illness representation and medication adherence was conducted. Articles were searched using MEDLINE, PreMEDLINE, evidence-based medicine reviews, and the International Pharmaceutical Abstracts databases and using the search terms medication adherence, compliance, illness perception, self-regulation theory, and common-sense model.

Results: Eleven published studies were identified that compared illness representation (or illness perception) and medication adherence. Each illness representation factor, with the exception of illness coherence, directly or indirectly impacted medication adherence. Illness identity, where symptoms are used to label a health condition, can impact medication adherence, even with asymptomatic conditions such as hypertension. Patient age, disease condition, and culture may impact patient response to illness perceptions. Recommendations for future research are to (1) use longitudinal studies to evaluate the cause-effect relationships between illness perceptions and medication adherence, (2) study patients' early experiences with their illness, (3) recruit patients who are nonadherent, (4) use clinical outcome measures in addition to the self-report medication adherence measures, and (5) include patient age and culture in the model.

Conclusions: Although the CSM is a well-known patient behavior model, its use to explain medication adherence has been limited to cross-sectional studies across various health conditions. Further research is needed to elucidate the relationships between illness perceptions and patient medication adherence, which can help practitioners to better engage and communicate with patients.