Definition of Resistant Hypertension
Resistant hypertension is defined as blood pressure that remains ≥140/90 mmHg despite concurrent use of three antihypertensive agents from different classes at optimal doses, ideally including a diuretic, OR blood pressure controlled with four or more medications. 1
Core Diagnostic Criteria
The definition encompasses two distinct patient populations:
Uncontrolled resistant hypertension: Blood pressure remains above goal (≥140/90 mmHg, or ≥130/80 mmHg in patients with diabetes or chronic kidney disease) despite adherence to at least three optimally dosed antihypertensive medications from different classes, with one being a diuretic 1, 2
Controlled resistant hypertension: Blood pressure is at goal but requires four or more antihypertensive medications to maintain control 1
Essential Components of the Definition
Medication requirements must be met: The three-drug regimen should include agents from different pharmacologic classes, prescribed at maximum or maximally tolerated doses 1, 3
Diuretic inclusion is critical: One of the three medications should ideally be a diuretic, as inadequate diuretic therapy is a common contributor to apparent resistance 1, 4
Thiazide-like diuretics preferred: Long-acting thiazide-like diuretics (chlorthalidone or indapamide) are superior to standard thiazides for resistant hypertension 5, 4
Exclusion of Pseudoresistance
Before confirming true resistant hypertension, several conditions must be ruled out:
White-coat hypertension: Approximately 50% of apparent resistant cases are due to white-coat effect, requiring confirmation with 24-hour ambulatory blood pressure monitoring or home blood pressure measurements 5, 6, 4
Medication non-adherence: Poor adherence is a leading cause of apparent resistance and must be verified through direct questioning, pill counts, or pharmacy records 5, 6, 7
Improper blood pressure measurement: Incorrect technique, inappropriate cuff size, or poor patient positioning can falsely elevate readings 5, 6, 2
Clinical Significance
This definition identifies high-risk patients: The arbitrary threshold of three medications serves to identify patients at elevated risk for reversible secondary causes of hypertension and those who may benefit from specialized diagnostic evaluation and treatment 1
Associated with increased cardiovascular risk: Resistant hypertension affects approximately 5% of the hypertensive population and is associated with significantly increased cardiovascular morbidity, mortality, heart failure, stroke, and renal failure 2, 3
Important Distinctions
Uncontrolled hypertension is not synonymous with resistant hypertension: Many patients have uncontrolled blood pressure due to inadequate treatment regimens or poor adherence rather than true treatment resistance 1
Refractory hypertension is a separate entity: This refers to blood pressure that remains uncontrolled despite five or more antihypertensive drugs from different classes, representing the most severe form of treatment resistance 2