Association of Visit-to-visit variability of Systolic Blood Pressure with Cardiovascular Disease and Mortality in Primary Care Chinese Patients with Type 2 Diabetes – A Retrospective Population-based Cohort Study

Abstract

OBJECTIVE: This study aimed to evaluate the impact of visit-to-visit variability (VVV) of systolic blood pressure (SBP) on cardiovascular disease (CVD) and mortality among primary care Chinese patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS: A retrospective cohort study was conducted in 124,105 Chinese adult primary care patients with T2DM and without prior diagnosed CVD from August 2008 to December 2009. The VVV of SBP was evaluated using SDs of SBP over 24 months. The risks of CVD and all-cause mortality associated with variability in SBP were evaluated using Cox proportional hazards regression. Subgroup analysis was conducted by the stratification of age, sex, duration of diabetes, the presence of chronic kidney disease, baseline SBP and trend, and the number and class of antihypertensive drugs.

RESULTS: A positive linear relationship between the VVV of SBP and the first incidence of CVD and all-cause mortality was identified over a median follow-up time of 39.5 months. Patients with a low SD of SBP of <5 mmHg had the lowest risks of CVD and all-cause mortality, and patients with an SD of SBP of ≥10 mmHg had significantly higher risks. For every 1 SD increase in the SD of SBP, the risks of CVD, all-cause mortality, and the composite of both events increased by 2.9% (95% CI 2.4–3.4%), 4.0% (95% CI 3.5–4.6%), and 3.4% (95% CI 3.0–3.8%), respectively. A direct linear relationship was also observed in all selected subgroups.

CONCLUSIONS: SBP variability, irrespective of the mean SBP level, is a potential predictor for the development of CVD and all-cause mortality in patients with diabetes. In addition to monitoring BP targets for their patients with diabetes, clinicians should also remain vigilant about the visit-to-visit fluctuation of BP.