Factors Associated with Non-Adherence to Drugs in Patients with Chronic Diseases Who Go to Pharmacies in Spain.

Background: Pharmacological non-adherence in chronic diseases is 40-65%. No predictive profile of non-adherence exists in patients with multiple chronic diseases. Our study aimed to quantify the prevalence of non-adherence to pharmacological treatment and its associated factors in patients who visit pharmacies in Spain.
Methods: This observational cross-sectional study included patients with one or more chronic diseases. The variables analyzed were demographics, diseases involved, self-medication, information about disease, and lifestyle. The main variable was adherence using the Morisky-Green test. A total of 132 pharmacies collaborated, providing 6327 patients representing all Spain regions (April-December 2016). Bivariate and multivariate analyses were performed and the area under the receiver operating characteristic (ROC) curve was calculated.
Results: Non-adherence was 48.4% (95% confidence interval (CI): 47.2-49.7%). The variables that reached significance in the multivariate model were: difficulty in taking medication, self-medication, desire for more information, smoking, lower physical activity, younger age and number of chronic treatments. Discrimination was satisfactory (area under the ROC curve = 70%). Our study found that 50% patients was non-adherent and we obtained a profile of variables associated with therapeutic non-adherence.
Conclusions: It is cause for concern that in patients with multiple diseases and taking multiple medications, there is an association between non-adherence, self-medication and worse lifestyle.