Prevalence and Comorbidities of Resistant Hypertension: A Collaborative Population-Based Observational Study.

Background: Resistant hypertension, is a clinical condition that may confer high cardiovascular risk. Aim of the observational study was to evaluate the prevalence of resistant hypertension, and the association with cardiovascular risk factors or diseases in the Verona urban area.
Design and Methods: Eleven family doctors retrieved anonymised data concerning blood pressure, diagnosis of hypertension and treatments from a population of 17,502 adult subjects. The prevalence of resistant hypertension was estimated considering patients who had been consecutively treated with at least four antihypertensive medications, regardless of blood pressure values. Further search concerning the clinical characteristics associated with resistant hypertension was performed in a random subsample of 55 patients.
Results: The prevalence of hypertension was 21.9%, that of resistant hypertension was 2.1%, approximately 10% of the whole hypertensive population. High prevalence of diabetes mellitus (53%) and hyperlipidemia (83%) was found in association with resistant hypertension. As for end organ damage, high prevalence of carotid artery stenosis (45%), ischemic heart disease (43%) and left ventricular hypertrophy (40%) was observed in patients with resistant hypertension. Blood pressure was higher than 140/90 mmHg in 58% of patients in spite of treatment with four or more different antihypertensive drugs. The average age, systolic and pulse pressure were significantly higher in the subgroup of patients with resistant hypertension.
Conclusions: Patients with resistant hypertension are characterised by a higher systolic and pulse pressure and a very high attributable cardiovascular risk, due to high prevalence of cardiovascular risk factors and overt organ damage and cardiovascular disease.