LAUSR

Objective: Inadequate adherence to anti-hypertensive prescription is one of the major obstacles for blood pressure control in patients with arterial hypertension. It is estimated that 40% of patients with hypertension have partial or absent compliance, with more than 80% of non-adherence when blood pressure targets are not achieved. However, in clinical practice the assessment of therapeutic adherence is still challenging. The available methods for the assessment of anti-hypertensive compliance are costly, low accurate or time consuming. Design and method: We designed a prospective observational study to evaluate the therapeutic adherence to inhibitors of renin-angiotensin-aldosterone system (RAAS) in patients with hypertension through serial measurement of aldosterone-to-direct renin ratio (ARR), before and after treatment. We enrolled 80 patients, including 40 patients with arterial hypertension and 40 healthy controls. Patients with arterial hypertension underwent three visits: at baseline and 2 and 8 weeks after initiation of RAAS inhibitors. Patients of the control group underwent two visits: at baseline and after 2 weeks. At each visit we collected blood specimens for hormonal assays and therapeutic drug monitoring, used as gold standard for therapeutic adherence. We used delta ARR (ARR), defined as the relative change in ARR before and after treatment, for assessment of therapeutic compliance. Results: After initiation of RAAS inhibitor, aldosterone significantly decreased and renin levels significantly increased, with consequent ARR reduction. The use ARR provided high accuracy for determination of therapeutic compliance, with an area under the curve (AUC) of 0.900 and 0.886, at 2 and 8 weeks respectively. A cut-off of -48% of ARR was adopted, providing 90% sensitivity and 75% specificity, both at 2 and 8 weeks. Conclusions: The ARR measurement, is an innovative, cheap and highly sensitive method to predict compliance to RAAS inhibitors in patients with hypertension. We hence propose the implementation of ARR as screening test for identification of patients suspected to be non-adherent, reserving therapeutic drug monitoring for non-adherence confirmation.