Antihypertensive Drug-Related Side Effects: Is It the Unique Indicator for Nonadherence?

To the Editor: We’ve read with great interest the article “Drug Side Effect Symptoms and Adherence to Antihypertensive Medication” by Tedla et al.,1 reporting the significant contribution of the adverse effects of antihypertensive agents in treatment discontinuation. Poor compliance to antihypertensive therapy is associated with worse blood pressure control2 and increased cardiovascular morbidity and mortality.3 Given the clinical significance of the study findings, we would like to ask for clarification of some aspects. First of all, the study included both patients who started or restarted antihypertensive drug therapy. It would, therefore, be very important from the clinical point of view to know whether any differences in adherence rates between the beginners and restarters of antihypertensive therapy were noticed in the study. Another important aspect is the correlation between nonadherence and body mass index and polypharmacy. Obesity is associated with increased comorbidities, such as hypertension, diabetes mellitus, metabolic syndrome, dyslipidemia, congestive heart failure, and depression.4 It thus seems rationale to assume that study participants were concomitantly receiving several drugs along with antihypertensive treatment. Accumulating evidence indicates that the adherence decreases when the number of pills per day increases. Both polypharmacy and comorbidities might negatively influence patient’s compliance to antihypertensive therapy. Consequently, we would be obliged to the authors if they could provide data regarding the adherence levels among lean, overweight, and obese patients, as well as according to the number of administered drugs. The association between nonadherence and blood pressure control might be bidirectional. Poor adherence is associated with worse blood pressure control, and vice versa adequate blood pressure reduction might be a significant motivating factor to continue antihypertensive therapy. In the case that antihypertensive efficacy was assessed in this study, it would be clinically important to know whether adherence rates were higher in responders compared to nonresponders. Finally, the study includes mainly Caucasian (88.5%), highly educated patients. The adherence levels might be influenced by social and economical factors. Therefore, relevant data, if available, might be elucidating.