Background: Low adherence to pharmacological therapy by patients with diabetes mellitus and hypertension is frequent and represents a worldwide challenge. Introduction: This study examined the effect of an educational intervention using WhatsApp® messaging on medication adherence of patients with hypertension and diabetes. Materials and Methods: A randomized clinical trial was performed with 403 patients who had diabetes and/or hypertension and who had enrolled in the 33 Basic Health Units of Maringá-PR, Brazil. The patients were randomly assigned to either the intervention group (n = 203), which received usual care (multi-professional educational appointments according to each Unit schedule) plus 55 audio, image or text WhatsApp messages about health care promotion, with an emphasis on medication adherence, or the control group. The control group (n = 200) only received usual care. Medication adherence, as measured by the Morisky-Green Test, was compared through the chi-square test after 16 weeks. Relative risk (RR) was used as a measure of effect size. Results: After the follow-up period (4 months), 67.5% of the patients in the intervention group were adherent versus 58.5% in the control group (RR: 1.15, 95% confidence interval = 0.99-1.34, p = 0.077). Discussion: Although the effect of the intervention was not statistically significant, there was a clinically significant impact associated with a 15% increase in medication adherence. Conclusion: Given the complexity of adherence to the use of antidiabetic and antihypertensive medications, educational interventions using WhatsApp could be useful as a reinforcement to increase adherence to medication.
Keywords: chronic disease; health promotion; health technology; telemedicine.