EDMONTON, Alberta -- October 26, 2009 -- Obese patients have a much reduced likelihood of achieving either blood pressure or cholesterol targets than normal-weight individuals, according to a prospective study with more than 7,000 high-risk patients. The study demonstrated an inverse relationship between increasing weight and likelihood of reaching targets. The study, presented October 25 at the 2009 Canadian Cardiovascular Congress (CCC), provides compelling evidence that clinicians may not be able to control these risk factors on drugs alone.
"This, to our knowledge, is the first study looking at patients with established cardiovascular disease who are on treatment to see how obesity relates to the control of these risk factors," reported first author Vineet Bhan, MD, University of Toronto, Toronto, Ontario. Although the reason that the obese are less responsive to pharmacological management of risk factors is unclear, the data suggest some type of innate resistance to conventional drug strategies.
In this study, 7,357 outpatients with coronary artery disease, cerebrovascular disease, peripheral artery disease, or diabetes and at least 1 other risk factor, were evaluated at 9 treatment centres in Canada. Patients were stratified into 3 weight groups based on body mass index (BMI): normal weight (BMI <25 kg/m2), overweight (BMI of >25 but <30 kg/m2), and obese (BMI >=30 kg/m2). The low density lipoprotein (LDL) goal was <100 mg/dL, and the blood pressure goal was <140/90 mm Hg (<130/80 mm Hg in patients with diabetes).
All treatment goals were reached in 26.5% of those with normal weight, 23.9% of those who were overweight, and 17.3% for those who were obese (P < .001 for obese vs normal weight). Although the difference by weight in those reaching the LDL goal was of modest significance (45% vs 48.1%; P = .021), only 34.2% of the obese versus 52.4% of those with normal weight (P < .001) met the blood pressure goals (the proportion of overweight patients at goal fell between the obese and normal weight patients for all measures).
Although Dr. Bhan's co-author on this study, Andrew Yan, MD, who is also from the University of Toronto, cautioned that it cannot be assumed that increased weight directly impairs the activity of pharmacological agents, he said that the reduced efficacy "is a potentially important message to get across to clinicians, especially primary care physicians who are on the frontline managing these high-risk patients in the long term."
CCC is co-hosted by the Canadian Cardiovascular Society and the Heart and Stroke Foundation of Canada.
[Presentation title: Obesity Is Associated With Failure to Attain Optimal Blood Pressure and Lipid Targets in High Vascular Risk Outpatients in Canada. Abstract 222]
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