April 03, 2018
3 min read

Tight blood pressure control may increase risk for CVD, mortality in type 2 diabetes

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Adults with type 2 diabetes and hypertension who achieved a target systolic blood pressure of less than 130 mm Hg did not experience a reduction in cardiovascular risk when compared with similar patients with systolic blood pressure between 130 and 140 mm Hg, according to findings from researchers in Hong Kong.

The observational findings, based on a population-based cohort study using a clinical trial modeling approach, also found that treating patients with diabetes and comorbid hypertension to systolic BP targets of less than120 mm Hg or less than 130 mm Hg may potentially be associated with increased risk for CVD and mortality when compared with patients treated to a target systolic BP of less than 140 mm Hg.

“The Framingham Heart Study found that patients with coexisting hypertension and diabetes have an associated 25% higher risk for CVD and 30% higher risk for all-cause mortality compared with normotensive individuals with diabetes and recommend BP control as a key intervention for the primary prevention of CVD,” Eric Wan Yuk Fai, a doctoral student in the department of family medicine and primary care at the University of Hong Kong, and colleagues wrote. “Most international diabetes guidelines include treatment targets for systolic BP, although there is currently no consensus on the ideal target.”

Fai and colleagues analyzed data from 28,014 adults managed in general outpatient clinics of the Hong Kong Hospital Authority with type 2 diabetes and hypertension (systolic BP at least 130 mm Hg) and without a prior history of CVD, recruited between January 2009 and December 2011. Researchers only included adults with a documented decrease in systolic BP after an enhanced hypertension regimen at baseline to maximize the likelihood that BP reductions reflected pharmacologic treatments. Participants were stratified into three achieved systolic BP groups: below 120 mm Hg (n = 2,079 ; mean age, 67 years; 48.24% men ) , below 130 mm Hg (n = 10,851 ; mean age, 66 years; 47.29% men ) and below 140 mm Hg (n = 15,084 ; mean age, 67 years; 46 .55% men ) . Participants were followed from baseline (defined as the date when patients first had an increase in antihypertensive d rugs prescribed) to the date of CVD event, all-cause mortality or November 2015. Primary outcome was a CVD event , and secondary outcomes included incident coronary heart disease, heart failure, stroke and all-cause mortality. Researchers used Cox proportional hazards regression to estimate the effect of different systolic BP groups on the incidence of CVD events.

Within the cohort, 9.8% were smokers, mean diabetes duration was 7.3 years , and 33.2% were prescribed at least three kinds of antihypertensive drugs on or before baseline. For all three systolic BP groups, patients achieved the corresponding systolic BP level after baseline and maintained a relatively stable systolic BP subsequently.

Over a median follow-up of 4.8 years, the incidence of CVD in patients with achieved systolic BP measurements of less than 120 mm Hg, less than 130 mm Hg and less than 140 mm Hg were 318 (15.3%; incidence rate, 34.3 per 1,000 person-years ), 992 (9.1%; incidence rate, 20.4 per 1,000 person-years) and 1,635 (10.8%; incidence rate, 21.4 per 1,000 person-years). Researchers observed similar patterns for outcomes for coronary heart disease, heart failure and stroke.

Using patients who achieved a systolic BP target of 140 mm Hg as the reference group, those who achieved a target systolic BP of below 120 mm Hg saw a marked increase in the incidence of CVD (HR = 1.67; 95% CI, 1.46-1.9); no difference in likelihood was seen in those who achieved a target systolic BP of less than 130 mm Hg. Results persisted after stratifying by CVD subtype. Achieving systolic BP targets of less than 120 mm Hg and less than 130 mm was associated with an increase in all-cause mortality, with HRs of 2.28 and 1.19 respectively (P = .003), when compared with patients treated to the systolic target of less than 140 mm Hg.

In subgroup analyses according to age, sex and other factors, researchers found that only patients aged 65 years and younger achieving the systolic BP target of below 130 mm Hg was saw the benefit of reduced CVD risk (HR = 0.81; 95% CI, 0.69-0.96), when compared with similar patients achieving the less than 140 mm Hg target, according to researchers.

“Our findings support the hypothesis that there is no risk reduction attenuation on CVD for lower [systolic] BP targets for most patients with uncomplicated [type 2 diabetes],” the researchers wrote, adding that a randomized controlled trial is needed to confirm the observational findings. – by Regina Schaffer

Disclosures: The authors report no relevant financial disclosures.