Relationship between blood pressure and incidence of cardiovascular diseases and mortality in patients with diabetes mellitus in Hong Kong

Abstract

Introduction: Blood pressure (BP) is a vital modifiable risk factor of cardiovascular diseases (CVD) and mortality amongst patients with Type 2 Diabetes Mellitus (T2DM). Although all international guidelines recommend adequate BP control, there is no consensus on the optimal BP level. The objective of this study was to examine the association between updated BP and incidence of CVD events and all-cause mortality. Method: A retrospective population-based cohort study was conducted on 125,277 Chinese adult primary care patients with T2DM and without CVD in Aug 2008 and Dec 2009. Using the average of the annual mean BP records (updated BP) before an outcome event over a median follow-up of 5.3 years, the risk of CVD and all-cause mortality associated with BP were evaluated using multivariable Cox proportional hazards regression analysis of adjustment of socio-demographics and clinical characteristics. Results: A J-shaped curvilinear relationship was identified between updated BP and CVD incidence and all-cause mortality. Low BP (<125/<60mmHg) or high BP (≥140/≥80mmHg) was associated with elevated risk of events. The optimal BP range for a lower likelihood of CVD and all-cause mortality was a systolic BP (SBP) of 130-139mmHg and a diastolic BP (DBP) of 60-79mmHg. Conclusions: In Chinese primary care patients with T2DM, the optimal BP level of SBP 130-139mmHg and DBP 60- 79mmHg was identified for the prevention of CVD events and all-cause mortality. Clinicians need to be cautious about excessive lowering of SBP <125mmHg or DBP <60mmHg in patients without existing complications.