Prevalence, reasons and factors associated with intentional nonadherence to prescribed medications: a population-based study.

Objective: To evaluate the frequency, reasons and factors associated with intentional nonadherence to drug therapy.

Methods: A population-based cross-sectional study was conducted with data from the National Survey on Access, Use and Promotion of Rational Use of Medicines (PNAUM). The questionnaire consisted of sociodemographic questions, presence of chronic diseases, medication use, self-rated health, and medication use behaviors. Data analysis included Poisson regression models adjusted for variance.

Results: A total of 31,573 individuals were included, most of whom were women (53.8%), with low level of education (57.7%), and self-rated good health (56.5%). Of those interviewed, 8.8% reported increasing the medication dose and 21.2% reported reducing it. The most common reason for dose reduction was the adverse effects of the medication. There were no differences in the reasons for increasing doses. Increasing or reducing doses were most commonly reported by younger people, with lower per capita income and worse self-rated health.

Conclusion: A considerable portion of the respondents did not intentionally adhere to drug therapy. Understanding nonadherence and identifying those who practice it is crucial for creating effective strategies that promote adherence to treatment and prioritize patients' needs and perspectives.