Association between self-medication with antibiotics and purchase of brand-name drugs: analysis of a national survey in Peru

To determine the association between self-medication with antibiotics (SMA) and purchase of brand-name drugs in Peru. A secondary analysis was conducted using a nationally representative survey from 2014 to 2016. The exposure variable was self-medication (SM), which is defined as the purchase of drugs for self-administration without a medical prescription. The study outcome was the purchase of brand-name drugs (yes/no). Sociodemographic variables, such as health insurance and type of institution, were considered as confounders. To assess the association between SMA and the purchase of brand-name drugs, the crude prevalence ratios (cPR) and adjusted prevalence ratios (aPR) were calculated with their confidence intervals at 95% (95% CI) using a Poisson-type generalized linear model and considering the complex survey design. A total of 1862 participants were analysed; 54.4% of the participants were women with a mean age of 39.3 years. The prevalence rate of SMA was 54.3%, whereas that of the purchase of brand-name drugs was 55.3%. The adjusted Poisson regression analysis showed an association between SMA and the purchase of brand-name drugs (aPR = 1.28; 95% CI: 1.18–1.37; P < 0.001). It was found that 5 of 10 respondents SMA. Approximately 6 of 10 respondents that SMA used brand-name drugs. SMA is associated with a higher probability of purchasing brand-name drugs.