Initial treatment with a single capsule containing half-dose quadruple therapy versus standard-dose dual therapy in hypertensive patients (QUADUAL): statistical analysis plan for a randomized, blinded, crossover trial.

BACKGROUND: Combined antihypertensive therapy has obvious advantages over single drug therapy. Hypertension guidelines fully affirm the efficacy of dual combination in initial antihypertensive therapy. Recent studies have also pointed out that the quadruple combination of very low-dose antihypertensive drugs is superior to single drugs. However, whether low-dose quadruple therapy is better than dual combination is unknown.

METHODS/DESIGN: A randomized double-blind crossover clinical trial will be conducted to compare the efficacy and safety of low-dose quadruple antihypertensives (irbesartan 75 mg + metoprolol 23.75 mg + amlodipine 2.5 mg + indapamide 1.25 mg) with standard-dose dual antihypertensives (irbesartan 150 mg + amlodipine 5 mg) in the initial treatment of patients with mild to moderate hypertension (140-179/90-109 mmHg). Ninety patients are required and will be recruited and randomly assigned in a 1:1 ratio to two crossover groups. Two groups will receive a different combination therapy for 4 weeks, then switch to the other combination therapy for 4 weeks, with a 2-week wash-out. Antihypertensive effects and related adverse effects of the two antihypertensive combination treatments will be compared. The primary outcome, i.e., mean 24-h systolic blood pressure in ambulatory blood pressure monitoring, will be assessed via linear mixed-effects model.

DISCUSSION: This statistical analysis plan will be confirmed prior to blind review and data lock before un-blinding and is sought to increase the validity of the QUADUAL trial.

TRIAL REGISTRATION: ClinicalTrials.gov, NCT05377203. Registered May 11, 2022, https://clinicaltrials.gov/study/NCT05377203 .