Aggressive blood pressure lowering, and the degree of a patient’s adiposity, appear unrelated to cardiovascular disease outcomes in individuals with diabetes, according to a new analysis of data from the large, randomized controlled trial, Action to Control Cardiovascular Risk in Diabetes, presented at the annual meeting of the American Diabetes Association in Philadelphia.
The subanalysis follows on findings from the original blood-pressure study (n = 4,733) that showed no difference in cardiovascular disease (CVD) risk between people with diabetes mellitus whose blood pressure was treated to less than 120 mm Hg, compared with those with the standard treatment goal of less than 140 mm Hg. The primary measure of CVD outcomes looked at a composite of nonfatal MI, nonfatal stroke, or CVD death (N. Engl. J. Med. 2010;362:1575-85).
That original study, however, did not control for waist-to-height ratios. Presumably, a waist-to-height ratio of less than 50% would be associated with less CVD risk, compared with a ratio higher than 50%, postulated Dr. Joshua I. Barzilay of Emory University, Atlanta, and his colleagues.
His team analyzed data from the 4,687 people in the ACCORD blood-pressure cohort for whom waist-to-height data were available. All subjects had diabetes and hypertension; 47.7% were women; the subjects’ mean age was 62.2 years; and the mean follow-up was 4.7 years. Intensive lowering of blood pressure did not improve combined CVD risk, compared with standard treatment, they found (Diabetes Care 2012;35:1401-5).
Although the investigators found that controlling for the waist-to-height quartile did not affect risk for the combined outcome measure as they had hypothesized it would, one secondary end point in the study (CVD death) was found to be significantly related to the waist-to-height quartile (hazard ratio, 2.32; 95% confidence interval, 1.40–3.83; P = .0009 comparing the heaviest to lightest quartiles). Neither of the two other secondary outcome measures – fatal or nonfatal stroke and nonfatal MI – was affected.
The association between central obesity and increased risk of CVD death (but not MI or stroke) was "surprising, because morbidity outcomes share similar pathomechanisms with mortality outcomes." However, they wrote, the finding was in keeping with some other published studies. Increased "levels of inflammation factors are more strongly associated with fatal than with nonfatal CVD events. Greater degrees of central obesity are related to increased inflammation levels," they wrote.
The study is limited by its post hoc design, modest number of outcomes measured, and short follow-up. "The power to detect significant differences by the degree of central obesity was limited. With longer follow-up and more events, statistical significance could possibly be achieved for several outcomes."
The subanalysis was funded by the National Heart, Lung, and Blood Institute, and other federal agencies. Aside from study medicines and equipment, which were donated by various manufacturers, no conflicts of interest were reported.