Age-specific associations between Systolic Blood Pressure and Cardiovascular Disease in Patients with Type 2 Diabetes Mellitus: A population-based cohort study

Abstract

Background: The relationship between systolic blood pressure (SBP) and cardiovascular diseases (CVD) among diabetic patients remains unclear. This aim of this study was to explore age-specific associations between SBP and CVD. Methodology: A population-based retrospective cohort study was conducted on 180,492 Chinese adult primary care patients with type 2 diabetes mellitus sampled in 2008-2010. Age-specific associations (<50,50–59,60–69,and 0–79 years) between the average SBP (mean SBP in the past two years) and risk of CVD were assessed by Cox proportional hazards regression with adjustments for age-specific regression dilution ratios and patient characteristics. Subgroup analyses stratified subjects’ characteristics were also performed. Results: During 9.3 years median follow-up, 32,545 subjects developed a CVD with an incidence rate of 23.4 per 1,000 person-years for CVD. A positive and log-linear association between SBP and CVD was observed across all four age groups with no evidence of a threshold down to 120mmHg, but the magnitude of the effect of SBP on CVD attenuated with increased age. The CVD risk per each 10mmHg higher SBP in the <50 years group was approximately three times higher than that in 70-79 years group(HR:1.33[95%CI:1.26-1.41] vs. HR:1.09[95%CI:1.07-1.11] ). Smokers had near ly twice the r isk compared to non-smokers for CVD(HR:1.21[95%CI:1.17-1.26] vs. HR:1.10[95%CI:1.08-1.12]). The associations were similar for other patient characteristics. Conclusions: The impact of SBP appears to be positive and log-linear associated with risk of CVD among Chinese diabetic population, with no evidence of a threshold down to 120mmHg. Age and smoking status appears to influence the strength of the associations. Hence, younger patients and smokers may receive the most benefit from lowering their SBP target. Individualised, age-stratified SBP targets in may be more appropriate for patients with diabetes.