Does decreasing serum uric acid level prevent hypertension? – a nested RCT in cohort study: rationale, methods, and baseline characteristics of study cohort

BACKGROUND: Previous epidemiologic studies have demonstrated an association between uric acid and hypertension. Our objective was to conduct a prospective cohort study with a nested randomised controlled trial (RCT in cohort) that aims to identify the association of hyperuricemia with the development of hypertension and to examine the efficacy of dietary intervention in lowering uric acid level and prevention of hypertension. METHODS/DESIGN: Participants were considered eligible to enrol for this cohort study if they were not diagnosed with hypertension until their last routine health examination. The characteristics of the eligible participants were analyzed. After enrolment, participants with prehypertension and hyperuricemia simultaneously were randomly distributed to either the intervention group or the control group. An education package of dietary intervention for lowering uric acid was delivered to the intervention group. The primary evaluation criterion was the first manifestation of hypertension. DISCUSSION: Based on the results of their health examination in 2010, 19, 724 subjects met the inclusion criteria and this source population guaranteed the required minimum sample size for this study. The baseline characteristics of the study cohort showed that hyperuricemia was associated with prehypertension, and was independent of age, body mass index (BMI), and abdominal obesity in females; however, in males it was contrary. The impact of lowering uric acid on the prevention of hypertension is still inconclusive. This RCT in cohort study provides important data on the prevention of hypertension, especially in patients with a high risk for hypertension development. Results are expected to be available in 2015. TRIAL REGISTRATION: The study is registered with the Chinese Clinical Trial Registry (ChiCTR-TRC-12002925).