bivalirudin and Obesity

To compare dosing strategies using total body weight (actual measured body weight), adjusted body weight, and ideal body weight when starting bivalirudin for the treatment for heparin-induced thrombocytopenia (HIT) in obese patients, and to compare differences in dosing requirements and clinical outcomes between obese and nonobese patients.. Retrospective medical record review.. Academic tertiary care medical center.. One hundred thirty-five medical and surgical patients who were treated with bivalirudin for HIT between June 1, 2004, and October 1, 2009.. The 135 patients were separated into two groups based on body mass index (BMI): 46 patients had a BMI greater than 30 kg/m(2) and were classified in the obese group; the nonobese group consisted of 89 patients with a BMI less than 30 kg/m(2) . The mean BMI in the obese group was 37.7 kg/m(2) (range: 30.1-56.2 kg/m(2) ). Weight-standardized doses that achieved activated partial thromboplastin time (aPTT) goal were compared in the obese group. The mean ± SD doses that achieved aPTT goal with total (actual), adjusted, and ideal body weights in this group were 0.1 ± 0.07, 0.11 ± 0.08, and 0.14 ± 0.09 mg/kg/hour, respectively. Of the three weight-based dosing approaches, total body weight followed by adjusted body weight provided the closest correlation to rates observed at the target aPTT goal. The secondary analysis compared initial doses of bivalirudin, doses required to reach goal aPTT, time to achieve goal aPTT, and clinical outcomes (number of patients not achieving goal, new thrombosis, major bleeding, and 30-day all-cause mortality) between the obese and nonobese groups. A significant difference in initial dose was noted between groups; however, no significant differences in dose required to achieve goal aPTT, time to achieve goal aPTT, and clinical outcomes were noted between the obese and nonobese groups.. This study provides evidence that the dosing strategy for bivalirudin based on total body weight is the most accurate predictor of achieving aPTT goal in obese patients with HIT. The study also suggests that there are no clinical differences that warrant different dosing strategies between obese and nonobese patients. Further prospective studies are needed to confirm these findings.

Topics: Adult; Aged; Aged, 80 and over; Body Mass Index; Body Weight; Dose-Response Relationship, Drug; Female; Heparin; Hirudins; Humans; Ideal Body Weight; Male; Middle Aged; Obesity; Partial Thromboplastin Time; Peptide Fragments; Recombinant Proteins; Retrospective Studies; Thrombocytopenia; Young Adult

The association between obesity and bleeding after percutaneous coronary intervention (PCI) is not well defined. We investigated the impact of body mass index (BMI) on PCI-related bleeding, and whether bivalirudin, compared to heparin, used as PCI anticoagulant modifies this relationship.. From 2000 to 2009, 16,783 patients who underwent PCI were grouped according to 6 BMI groups: underweight (<18.5 kg/m(2)), "normal" weight (18.5-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), class I (30-34.9 kg/m(2)), class II (35-39.9 kg/m(2)), and class III obesity (> or =40 kg/m(2)). Bivalirudin was used in 11,433 patients and heparin in 5,350. In-hospital major bleeding (hematocrit drop > or =15% or gastrointestinal bleeding) and need for transfusion rates were collected.. The incidence of major bleeding varied significantly throughout the BMI spectrum (5.6% vs 2.5% vs 1.9% vs 1.6% vs 2.1% vs 1.9%, respectively, from underweight to class III obese patients, P < .001). The incidence of transfusion across BMI followed the same reverse J-shape curve (10.9% vs 6.6% vs 3.6% vs 3.4% vs 3.8% vs 5.6%, P < .001). After adjustment for potential confounding factors, underweight patients had neither an increased risk for major bleeding nor an increased risk for transfusion compared with "normal" weight patients. Class I obese patients had a lower risk of major bleeding (odds ratio [OR] 0.68 [95% CI 0.48-0.97]). Overweight, class I, and II obese patients had a lower risk of transfusion (respectively, OR 0.68 [0.55-0.84], 0.68 [0.53-0.87], and 0.66 [0.48-0.92]). The highest BMI patients had neither an increased risk for major bleeding (class II and III obesity) nor an increased risk for transfusion (class III obesity). The same reverse J-shaped relationship to BMI seen in the overall population for the raw incidence of major bleeding was found when the population was divided according to type of anticoagulant used as follows: bivalirudin or heparin. Likewise, the "need for transfusion" relationship to BMI is not altered by bivalirudin use.. 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.

Topics: Aged; Angioplasty, Balloon, Coronary; Anticoagulants; Antithrombins; Body Mass Index; Coronary Disease; Female; Follow-Up Studies; Hirudins; Humans; Incidence; Male; Middle Aged; Obesity; Odds Ratio; Peptide Fragments; Postoperative Hemorrhage; Prognosis; Recombinant Proteins; Retrospective Studies; Risk Factors; Thrombosis