Unfractionated heparin infusion for treatment of venous thromboembolism based on actual body weight without dose capping

Abstract

Controversy exists regarding the use of dose capping of weight-based unfractionated heparin (UFH) infusions in obese and morbidly obese patients. The primary objective of this study was to compare time to first therapeutic activated partial thromboplastin time (aPTT) in hospitalized patients receiving UFH for acute venous thromboembolism (VTE) among three body mass index (BMI) cohorts: non-obese (< 30 kg/m2), obese (30–39.9 kg/m2), and morbidly obese (⩾ 40 kg/m2). In this single-center, retrospective cohort study, patients were included if they ⩾ 18 years of age, had a documented VTE, and were on an infusion of UFH for at least 24 hours. Weight-based UFH doses were calculated using actual body weight. A total of 423 patients met the inclusion criteria, with 230 (54.4%), 146 (34.5%), and 47 (11.1%) patients in the non-obese, obese, and morbidly obese cohorts, respectively. Median times to therapeutic aPTT were 16.4, 16.6, and 17.1 hours in each cohort. Within 24 hours, the cumulative incidence rates for therapeutic aPTT were 70.7% for the non-obese group, 69.9% for the obese group, and 61.7% for the morbidly obese group (obese vs non-obese: HR = 1.02, 95% CI: 0.82–1.26, p = 0.88; morbidly obese vs non-obese: HR = 0.87, 95% CI: 0.62–1.21, p = 0.41). There was no significant difference in major bleeding events between BMI groups (obese vs non-obese, p = 0.91; morbidly obese vs non-obese, p = 0.98). Based on our study, heparin dosing based on actual body weight without a dose cap is safe and effective.

Unfractionated heparin using actual body weight without dose capping in obese pediatric patients—Subgroup analysis from an observational cohort study

“…Adult case series and retrospective cohort studies, however, do not uniformly support this hypothesis. Shlensky and colleagues recently performed a retrospective cohort study of 423 adult patients requiring uncapped UFH for venous thromboembolism management 2 ; 194 patients (45.6%) were obese or morbidly obese. No significant differences were observed in the median time to therapeutic activated partial thromboplastin time (aPTT) or rates of major bleeding between obese/morbidly obese and nonobese patients, and the authors concluded that dose capping based on body weight was not required 2 .…”

“…Shlensky and colleagues recently performed a retrospective cohort study of 423 adult patients requiring uncapped UFH for venous thromboembolism management 2 ; 194 patients (45.6%) were obese or morbidly obese. No significant differences were observed in the median time to therapeutic activated partial thromboplastin time (aPTT) or rates of major bleeding between obese/morbidly obese and nonobese patients, and the authors concluded that dose capping based on body weight was not required 2 . Other adult studies, in contrast, have shown that obese/morbidly obese patients require lower infusion rates, per kilogram of body weight of UFH, to achieve therapeutic levels 13–15 …”

“…Obesity is an increasingly common occurrence in pediatric medicine, with an estimated 17% of children/adolescents in the United States being classified as obese 1 . Though adult data suggest that dosing unfractionated heparin (UFH) based on actual body weight without a dose cap in obese patients may be safe, pediatric data regarding this practice are scarce 2–5 . We have previously reported results of an observational cohort study conducted over 20 months, establishing the use of an anti‐factor Xa (anti‐FXa)‐based nomogram to monitor UFH use in children 3 .…”

“…Though adult data suggest that dosing unfractionated heparin (UFH) based on actual body weight without a dose cap in obese patients may be safe, pediatric data regarding this practice are scarce 2–5 . We have previously reported results of an observational cohort study conducted over 20 months, establishing the use of an anti‐factor Xa (anti‐FXa)‐based nomogram to monitor UFH use in children 3 . All patients in the reported cohort received uncapped, actual body weight‐based dose of UFH.…”

Anticoagulants in the Management of Pulmonary Embolism

“…Warfarin can be safely used in patients with liver dysfunction. Elevations in baseline INR due to liver disease, however, may lead to unclear INR targets during warfarin therapy [80,81]. LMWHs have a good safety profile with liver dysfunction; however, subcutaneous administration may limit compliance, and lower anti-Xa levels in liver dysfunction limit efficacy monitoring [82,83].…”