Background: The aim of our study was to assess the prevalence of pseudo-resistance caused by noncompliance with treatment among patients with severe resistant hypertension and to analyze the contributing factors.
Method: Three hundred and thirty-nine patients (195 men) with resistant essential hypertension were studied. The first group consisted of 176 patients admitted for hospitalization for exclusion of a secondary cause to our hypertension centre (103 men); the second one consisted of 163 out-patients (92 men) investigated for the first time in an out-patient hypertension clinic. Unplanned blood sampling for assessment of serum antihypertensive drug concentrations by means of liquid chromatography–mass spectrometry was performed in all patients.
Results: Our main finding is a surprisingly low compliance with drug treatment in out-patients with resistant hypertension (23% partially noncompliant and 24% totally noncompliant – in total, 47% prevalence of noncompliance). Eighty-one percent of hospitalized patients were positive, in 10% the results were partially positive and in 9% of the patients, the drugs were all negative. The compliance among hospitalized patients was probably better due to lower numbers of prescribed drugs and expected thorough investigation. More frequently, noncompliance was found in nonworking (potential purpose-built behaviour), younger and less well educated patients. The most frequent noncompliance was to doxazosine, spironolactone and hydrochlorothiazide. We have observed a surprisingly low compliance with treatment among out-patients with severe hypertension.
Conclusion: We conclude that the evaluation of antihypertensive drugs concentrations is a useful and precise method for assessment of noncompliance in patients with resistant hypertension. This evaluation is useful before starting the diagnostic work-up of secondary forms of hypertension and before assignment patients into protocols with new therapy modalities such as renal denervation.
a3rd Department of Medicine, Department of Endocrinology and Metabolism, Hypertension Center
bInstitute of Forensic Medicine and Toxicology, Toxicology Laboratory, General University Hospital, 1st Faculty of Medicine, Charles University, Prague
cInstitute for Clinical and Experimental Medicine, Prague
d2nd Department of Medicine, General University Hospital, 1st Faculty of Medicine, Charles University, Prague, Czech Republic
Correspondence to Branislav Štrauch, MD, PhD, 3rd Department of Medicine, Endocrinology and Metabolism, General University Hospital, U nemocnice 2, 128 08 Praha 2, Czech Republic. Tel: +420224963073; fax: +420224963245; e-mail: firstname.lastname@example.org
Abbreviations: 24h-ABPM, twenty-four-hours ambulatory blood pressure monitoring; ACEIs, angiotensin-converting enzyme inhibitors; ARBs, angiotensin II receptor blockers; BP, blood pressure; CHD, coronary heart disease; CYP, cytochrome P-450; LC/MS/MS, liquid chromatography–mass spectrometry
Received 6 June, 2013
Accepted 17 July, 2013
Information about previous presentations of the whole or part of the work presented in the article: previously, the data were presented in part at scientific meetings as abstracts.