SPIRO-First: A Pragmatic Primary Care-Embedded Pilot Trial of Renin-Guided First-Line Antihypertensive Therapy

The goal of this clinical trial is to determine whether a renin-guided antihypertensive treatment strategy is feasible to implement in community primary care clinics and to explore whether spironolactone improves blood pressure control in adults with low-renin hypertension. The main questions it aims to answer are: Is it feasible to identify, recruit, randomize, and follow adults with low-renin hypertension in a pragmatic primary care-based clinical trial? Does first-line treatment with spironolactone result in greater reductions in ambulatory blood pressure compared with standard first-line antihypertensive therapy among adults with low-renin hypertension? Researchers will compare spironolactone 25 mg daily with standard first-line antihypertensive therapy (candesartan, hydrochlorothiazide, or amlodipine) to determine whether spironolactone provides better blood pressure control in adults with low-renin hypertension. Participants will: Undergo blood pressure assessments, blood tests, and ambulatory blood pressure monitoring (ABPM) to determine eligibility. Be randomly…

• PRIMARY OUTCOME: Recruitment Rate of Randomized Participants per Month

1. Study completion expected

   Dec 2028

2. Primary completion expected

   Aug 2028

3. Expected to start

   1 Jan 2027

4. Last registry update

   14 Oct 2026

5. Registered

   7 Jul 2026