CHEMICAL ADHERENCE IN RESISTANT HYPERTENSION: PILOT STUDY IN AN ESH EXCELLENCE CENTER

Abstract

Objective: Arterial hypertension (HTN) is responsible for the largest proportion of preventable mortality in the world. The primary cause of resistant hypertension (rHTN) is poor medication adherence. Blood or urine drug assays enable us to assess chemical adherence more accurately than self-reported questionnaires. We assayed anti-hypertensive drugs in patients with rHTN at our Center of Excellence in Hypertension, in collaboration with the Pharmacology and Toxicology Laboratory. Design and method: Patients with rHTN (office SBP/DBP >140/90 mmHg or out of office daytime >135/85 mmHg despite being prescribed 3 drugs at optimal dosage, including a diuretic, a renin angiotensin system inhibitor (RASI) and a calcium channel blocker (CCB), were informed of the study and agreed to have blood drugs concentrations measured. We describe the results for chemical adherence in the first 54 patients included between January 1, 2021 and September 1, 2023 in our center. Results: Of the 54 patients included, 38 (70%) were men, with a mean age of 65 +/- 11 years. The mean number of antihypertensive treatments prescribed was 5 +/- 1 (min 3, max 8). The proportions of treatments were RASI 87%, CCB (mainly dihydropyridines) 81%, diuretics 81%, beta-blockers 76%, alpha-blockers 57%, mineralocorticoid receptor antagonists (MRA) 37%, and central antihypertensives 26%. The best compliance was observed with alpha-blockers 81%, followed by CCB 50%, RASI 45%, diuretics 37% and beta-blockers 34%. The least compliant were central antihypertensives 0% and MRA 5%. All prescribed drugs were completely absent in the blood in 26% of patients, and 63% of patients had incomplete adherence (1 or more but not all drugs present in the blood), of whom 1/3 were non-compliant to 3 or more medications. Only for 9% of patients chemical adherence was excellent. Conclusions: Chemical adherence when measured at clinical visit was poor in this cohort of patients followed in a center of excellence. Limitations of this study are lack of follow-up for the same patient to assess variation in adherence over time, and small sample size. These results suggest the need to develop therapeutic education to improve patient involvement in the management of HTN and compliance.