Ambulatory blood pressure monitoring is a fundamental tool to diagnose RH, and to check treatment efficacy. The presence of a greater pulse pressure and a lower nocturnal blood pressure reduction in true RH patients may be responsible for this increased cardiovascular risk profile.
Background:
The prevalence, predictors and the best anti-hypertensive regimen for resistant hypertension (RH) are not well established especially in Countries with multiethnic profile. Our main aim was to compare spironolactone versus clonidine as a fourth drug therapy for patients with RH.
Methods:
This is a multicentric, randomized controlled trial comprising 26 sites in Brazil that recruited outpatients from a highly admixed population with hypertension stage 2 (≥160/100mmHg) at study entry. Medical therapy adherence was checked by pill counting. Patients with confirmed RH (no office and 24hs ambulatory blood pressure monitoring - ABPM - control despite treatment with 3 drugs including a diuretic for 12 weeks) were randomized to additional 12 weeks treatment with spironolactone (12.5-50mg once daily) or clonidine (0.1-0.3mg twice daily). The primary endpoint was blood pressure (BP) control from both office (<140/90mmHg) and 24hs ABPM (<130/80mmHg). Secondary endpoints included absolute and relative BP reductions in each study arm.
Results:
A total of 1597 patients were included in the analysis. We found that 14.9% (238 patients) fulfilled the RH criteria. Predictors of true RH include male gender (OR 1.43; CI 1.02-2.00), previous stroke (OR 2.81; CI 1.51-5.06), diabetes (OR 2.09; CI 1.48-2.94) and BP ≥180x110mmHg at study entry (OR 2.53; CI 1.88-3.43). Compared to patients randomized to spironolactone (n=119), those patients randomized to clonidine (n=119) presented similar rate of the primary endpoint (19.8 vs. 24%, respectively; p=0.59). Similarly, no differences were observed between groups in the blood pressure reduction analyzed either by office as well as by 24-h ABPM. No differences in the pill counting monitoring were observed in the groups.
Conclusions:
Appropriate treatment for stage 2 hypertension under the national universal health care conditions provided blood pressure control in 85% from a highly admixed population. Spironolactone or clonidine displayed comparable BP control as a fourth drug in patients with RH.
Funding:
Ministry of Health/H. Samaritano, National Research Council, Sao Paulo Research Foundation and Zerbini Foundation.
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