Prevalence and characteristics of adverse drug events in Brazil.

The aim of this study was to describe the prevalence of adverse drug events (ADEs) and associated factors reported by users of medicines in Brazil. This was a cross-sectional population-based study conducted from September 2013 to February 2014 with data from the Brazilian National Survey on Access, Use, and Promotion of Rational Use of Medicines (PNAUM). The study included all individuals that reported the use of medicines and identified, among them, all those reporting at least one problem with the medicine's use. A descriptive analysis was performed to estimate ADE prevalence and 95% confidence intervals (95%CI) among the target variables. Crude and adjusted prevalence ratios were calculated using Poisson regression to investigate factors associated with ADEs. Overall ADE prevalence in Brazil was 6.6% (95%CI: 5.89-7.41), and after multivariate analysis, higher prevalence was associated with female gender, residence in the Central and Northeast regions, consumption of more medicines, "bad" self-rated health, and self-medication. The drugs most frequently reported with ADEs were fluoxetine, diclofenac, and amitriptyline. The most frequent ADEs were somnolence, epigastric pain, and nausea. Most reported ADEs were mild, avoidable, and associated with medicines used frequently by the population. The study provided knowledge on the size of the problem with use of medicines in Brazil.