New Insights Into Predictors of Antihypertensive Adherence A Mixed Methods Study of Illness Perceptions and the Physician-Patient Relationship

Background: Low adherence to treatment is the most common cause of uncontrolled hypertension. Evidence suggests that illness perceptions and the physician-patient relationship may have a combined effect on treatment adherence. Aims: We investigated the roles of illness perceptions and the physician-patient relationship in medication and lifestyle modification adherence, and explained them using patients' experiences with essential hypertension.Method: In this mixed methods explanatory sequential study, we used questionnaires to assess illness perceptions, the physician-patient relationship, and adherence to medication and lifestyle modification guidance (N = 112) in the first quantitative phase. Based on the results of regression analyses, the second qualitative phase was planned. We collected data from three patients through interviews, observations and journals, and conducted within-case and cross-case analyses. Finally, we integrated quantitative and qualitative findings. Results: The physician-patient relationship was an independent predictor of medication adherence (95% confidence interval [CI]: 0.29 to 5.89), whereas both illness perceptions (95% CI: -0.32 to -0.04) and the physician-patient relationship (95% CI: 1.05 to 9.48) were independent predictors of adherence to lifestyle modification guidance. Qualitative themes, reflecting the patient's experience of the concepts explored in this study, explained the quantitative results. Mixing methods revealed high consistency between quantitative and qualitative findings. Limitations: Limitations are the inability to infer causal associations among variables and indirect measurement of medication adherence. Conclusion: Shared decision-making on antihypertensive medications promotes medication adherence. Specifically, the illness perception, perceived illness controllability, and non-judgemental patients' acceptance within a satisfying physician-patient relationship empower patients to adhere to lifestyle modification guidance.