Patient's perception of medication and nonadherence to chronic disease treatments. A population-based study in Brazil

Objective: To identify the association between patients' perception of medication for hypertension, diabetes, and dyslipidemia and nonadherence by regions of Brazil.Methods: This is a cross-sectional study using open data from the urban population-based survey National Survey on Access, Use and Promotion of Rational Use of Medicines in Brazil (PNAUM), conducted from September 2013 to February 2014. Patients' self-reported perceptions recorded on each of the medicines for hypertension, diabetes, and dyslipidaemia were used for analysis. The dependent variable was nonadherence to treatment, and the patient's perceptions about medication were the independent variable. Logistic regression was performed to calculate the crude and adjusted odds ratios.Key findings: Nonadherence was observed in 6.6% of the 16 491 drugs, with missed doses (84.5%) being the main cause. In the adjusted analysis, perception of medication effectiveness considered regular or poor (OR 3.025; 95% CI 1.672-5.473), perception that caused discomfort (OR 2.731; 95% CI 1.464-5.092), and medicines used for <6 months (OR 1.557; 95% CI 1.089-2.227) had higher chances of nonadherence in Brazil (all regions).Conclusion: Patient perception of the effectiveness, safety, and time of use of medications are key factors associated with nonadherence and can contribute to building medication beliefs that may affect current and future adherence.