Nonadherence to antihypertensive treatment is a critical contributor to suboptimal blood pressure control. There are limited and heterogeneous data on the risk factors for nonadherence because few studies used objective-direct diagnostic methods. We used high-performance liquid chromatography-tandem mass spectrometry of urine and serum to detect nonadherence and explored its association with the main demographic- and therapy-related factors in 1348 patients with hypertension from 2 European countries. The rates of nonadherence to antihypertensive treatment were 41.6% and 31.5% in the UK and Czech populations, respectively. Nonadherence was inversely related to age and male sex. Each increase in the number of antihypertensive medications led to 85% and 77% increase in nonadherence (<0.001) in the UK and Czech populations, respectively. The odds of nonadherence to diuretics were the highest among 5 classes of antihypertensive medications (≤0.005 in both populations). The predictive model for nonadherence, including age, sex, diuretics, and the number of prescribed antihypertensives, showed area under the curves of 0.758 and 0.710 in the UK and Czech populations, respectively. The area under the curves for the UK model tested on the Czech data and for the Czech model tested on UK data were calculated at 0.708 and 0.756, respectively. We demonstrate that the number and class of prescribed antihypertensives are modifiable risk factors for biochemically confirmed nonadherence to blood pressure-lowering therapy. Further development of discriminatory models incorporating these parameters might prove clinically useful in assessment of nonadherence in countries where biochemical analysis is unavailable.

T he prevalence of patients with resistant hypertension (RH) varies from 5% to 30%.1 Identification of true-RH, when secondary causes and medication noncompliance are excluded, is becoming more important with the implementation of novel, nondrug therapeutic approaches to RH, such as catheter-based renal-artery denervation (RDN) or baroreflex stimulation. Pilot studies using RDN described the method as feasible, effective, and safe for reducing blood pressure (BP) in the short term. 2-4The interpretation of the results from the majority of these studies was complicated by the lack of 24-hour ambulatory blood pressure monitoring (24-hour ABPM) data, lack of compliance confirmation, or small follow-up sample sizes.This study seeks to evaluate the efficacy of RDN in a prospective multicenter randomized trial with the acronym PRAGUE-15 in patients with true-RH, according to the recommendations for RDN.5 Twenty-four-hour ABPM, exclusion of secondary hypertension and evaluation of treatment compliance served as confirmation of true resistance. The efficacy of RDN was compared with intensified antihypertensive treatment including the use of spironolactone. To date, only 1 study has compared RDN with intensified pharmacological treatment.6 However, only 19Abstract-This prospective, randomized, open-label multicenter trial evaluated the efficacy of catheter-based renal denervation (Symplicity, Medtronic) versus intensified pharmacological treatment including spironolactone (if tolerated) in patients with true-resistant hypertension. This was confirmed by 24-hour ambulatory blood pressure monitoring after excluding secondary hypertension and confirmation of adherence to therapy by measurement of plasma antihypertensive drug levels before enrollment. One-hundred six patients were randomized to renal denervation (n=52), or intensified pharmacological treatment (n=54) with baseline systolic blood pressure of 159±17 and 155±17 mm Hg and average number of drugs 5.1 and 5.4, respectively. A significant reduction in 24-hour average systolic blood pressure after 6 months (−8. Betweengroup differences in change were not significant. The average number of antihypertensive drugs used after 6 months was significantly higher in the pharmacological group (+0.3 drugs; P<0.001). A significant increase in serum creatinine and a parallel decrease of creatinine clearance were observed in the pharmacological group; between-group difference were borderline significant. The 6-month results of this study confirmed the safety of renal denervation. In conclusion, renal denervation achieved reduction of blood pressure comparable with intensified pharmacotherapy.