Efficacy and safety of intensive antihypertensive strategy in patients with low diastolic blood pressure: a secondary analysis of a cluster randomised trial

Background Intensive blood pressure (BP) control <130/80 mm Hg could bring additional benefits for cardiovascular disease (CVD). However, it is unclear whether intensive BP control remains effective and safe in the general hypertensive population with low diastolic BP (DBP) since a J-shaped relationship between DBP and CVD was observed. Methods This is a post hoc analysis of the China Rural Hypertension Control Project. Mixed-effect Cox proportional regression and generalised estimating equation models were used to determine HRs of outcomes by intensive BP control, stratified by baseline DBP quartiles. The interaction between intervention and DBP levels was assessed. Results A total of 33 288 participants were divided into four categories according to baseline DBP quartiles (Q1–Q4): DBP ≤80.7 mm Hg, 80.7–87.3 mm Hg, 87.3–94.3 mm Hg and >94.3 mm Hg, respectively. Compared with usual care, the intervention group reduced cardiovascular outcomes across DBP quartiles with adjusted HRs as follows: Q1: 0.69 (95% CI 0.58 to 0.83, p<0.001), Q2: 0.60 (95% CI 0.50 to 0.71, p < 0.001), Q3: 0.59 (95% CI 0.49 to 0.71, p < 0.001) and Q4: 0.67 (95% CI 0.56 to 0.78, p < 0.001). There was no evidence of interaction between DBP quartiles and groups (p = 0.987). The intervention group had a higher risk of hypotension, which was observed when stratifying by different baseline DBP levels. Intensive BP reduction did not increase the occurrence of injurious falls, syncope or adverse kidney outcomes. Conclusions The intensive BP intervention led by non-physician providers is both effective and safe in reducing CVD and mortality across all baseline DBP groups.