MedWire News: Patients in the middle range for body mass index (BMI) have comparable risk for major bleeding or need for blood transfusion after percutaneous coronary intervention (PCI) to those with a low weight, US researchers have found.
“The better outcome for bleeding seen in patients in the middle of the BMI spectrum suggests the existence of a ‘bleeding obesity paradox,’ which persists after adjustment by confounding factors and exists irrespective of the anticoagulant used,” comment Ron Waksman and co-authors from Washington Hospital Center in Washington, DC.
To determine the effect of obesity and choice of anticoagulant on bleeding risk after PCI, the team examined data for 16,783 PCI patients between 2000 and 2009 who were treated with bivalirudin (n=11,433) or heparin (n=5350).
The patients were divided by BMI into groups of underweight (<18.5 kg/m2), “normal” weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2), class I (30–34.9 kg/m2), class II (35–39.9 kg/m2), and class III obesity (≥40 kg/m2).
Overall, major bleeding, defined as an inhospital hematocrit fall of 15% or higher or gastrointestinal bleeding, significantly differed by BMI, occurring in 5.6% of underweight patients compared with 2.5% of normal and 1.9% of overweight patients, and 1.6%, 2.1%, and 1.9% of class I–III obese patients, respectively.
After taking into account confounding factors such as age, gender, and diabetes, underweight patients had an equivalent risk for major bleeding and transfusion to patients with normal weight.
However, the risk for major bleeding was significantly lower in class I obese patients than normal weight individuals (odds ratio [OR]=0.68), and the risk for transfusion was significantly lower in overweight, and class I and II obese patients than those with a normal weight (OR=0.68, 0.68, and 0.66, respectively).
Class II and III obese patients had no increased risk for bleeding compared with overweight individuals, and class III patients had a comparable risk for transfusion, the team reports in the American Heart Journal.
Waksman et al note that the “reverse J-shaped relationship” between BMI and major bleeding did not significantly differ in patients treated with bivalirudin or heparin. Nor did anticoagulant choice affect transfusion requirement.
The researchers suggest that higher levels of coagulation factors or suboptimal response to clopidogrel loading dose could explain the reduced risk for bleeding in mildly obese patients.
“The lack of benefit in bleeding for the highest BMI patients compared to patients of lesser obesity could be driven by a higher rate of vascular access-related bleeding at the femoral site,” they add.
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