Resistant hypertension is defined as blood pressure that does not drop below 140 mmHg systolic and/or above 90 mmHg diastolic, despite treatment with three drugs in suitable combination and recommended dosage, when one of the drugs is from the diuretic group. The prevalence of resistant hypertension, which has been examined in relatively few studies, ranges between less than 3% and up to 29%. The frequency of these causes has not yet been examined in Israel. The aim of this study is to examine the frequency of patients with resistant hypertension and to compare the frequency of the different causes for this condition in the primary community clinics with those found in the district advisory clinic for hypertension. The medical files of all of the patients above the age of 20, in five rural primary care clinics in the northern district and in the Advisory Clinic for Hypertension, were reviewed to find those patients meeting the criteria of resistant hypertension. The patients that were located and met the inclusion criteria filled out a questionnaire which included demographic characteristics, drug treatment updated to their last visit, and evaluation of the various possible causes for the condition.
Results: Resistant hypertension was found in 10 out of 227 hypertensive patients treated in primary clinics (4.4%) and in 21 out of 131 hypertensive patients treated in the Advisory Clinic for Hypertension (16%). For 8 of the patients (25.8%) there was a single cause for resistant hypertension. For 14 patients (45.2%) there were 2-3 causes and for 9 patients (29%) there were 4 or more causes. Low treatment compliance was found in 7 patients, faulty measuring technique in 3 patients and taking drugs that raise blood pressure was found in one patient. Among the accompanying clinical conditions, uncontrolled dyslipidemia was found in 15 patients (48.4%), uncontrolled diabetes in 11 patients (35.5%) and obesity in 10 patients (32.3%). Increased sympathetic activity was found in 6 patients (19.4%) and secondary causes were found in 4 patients (12.9%).
Conclusions: The frequency of resistant hypertension in primary clinics--4.4%, and in the Advisory Clinic for Hypertension--16%, as was found in our study, is identical to that described in the literature and derives from the different nature of the patients treated in each of them. The fact that in half of the patients 2-3 causes were found for resistant hypertension, and in a third of them there were 4 or more causes, emphasizes both the complexity of the medical problems of this patient group and the need for a comprehensive multi-systematic treatment approach.