Key result
Adjusted body weight heparin dosing linked to ~5-hour faster therapeutic anti-Xa levels in VTE.
Why the study?
Initial dosing strategies for weight-based unfractionated heparin in older adults and higher body weight patients with VTE remain uncertain due to pharmacokinetic differences and over-anticoagulation concerns.
Does adjusted body weight-based unfractionated heparin dosing reduce the time to therapeutic anti-Xa levels in older adults and higher weight patients with venous thromboembolism compared to total body weight-based dosing?
Cohort (n=80)
No
Does adjusted body weight-based unfractionated heparin dosing reduce the time to therapeutic anti-Xa levels in older adults and higher weight patients with venous thromboembolism compared to total body weight-based dosing?
Mean Difference: 5.3 (95% CI 0.2–9.9)
Absolute Event Rate: 13.6% vs 20.9%
p-value: p=0.02
Using adjusted body weight rather than total body weight for initial unfractionated heparin dosing significantly shortens the time to therapeutic anti-Xa levels in older adults with venous thromboembolism.
May support adjusted body weight dosing for faster therapeutic anti-Xa in older obese VTE patients; hypothesis-generating and should not yet change practice.
The use of weight-based unfractionated heparin (UFH) infusions is the standard of care in hospital management of venous thromboembolism (VTE). Initial dosing strategies for UFH in older adults and higher body weight patients remain uncertain given differences in pharmacokinetics and concerns for over-anticoagulation. Methods: This was a single-center, retrospective, pre-post study involving older adults aged ≥ 65 years and patients weighing ≥ 100 kg with suspected or confirmed VTE to determine if the use of adjusted body weight (AdjBW)-based UFH regimens improves time to therapeutic anti-Xa levels compared to total body weight (TBW)-based regimens Patients received weight-based UFH infusions, dosed according to either TBW or AdjBW, to target a therapeutic anti-Xa level. Each cohort consisted of 40 patients, stratified by whether they met age or weight criteria to ensure equal representation of elderly and higher body weight patients between cohorts. The median time to therapeutic anti-Xa levels was shorter in the AdjBW group compared to the TBW group (13.6 h versus 20.9 h; point estimate 5.3 h (95% CI 0.2 to 9.9)). This finding was driven by those aged ≥ 65 years and those who received a bolus dose at the start of the infusion. Among older adults and higher weight adults with suspected or confirmed VTE, the use of AdjBW to guide heparin infusion initiation was associated with shorter time to therapeutic anti-Xa levels. This finding driven by the older adult sample and the subgroup analyses did not find a statistically significant difference in time to therapeutic anti-Xa levels in higher body weight patients aged less than 65 years.
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Chau et al. (2024) conducted a cohort in Venous thromboembolism (n=80). Adjusted body weight (AdjBW)-based unfractionated heparin vs. Total body weight (TBW)-based unfractionated heparin was evaluated on Median time to first therapeutic anti-Xa level (MD 5.3, 95% CI 0.2-9.9, p=0.02). The use of adjusted body weight for unfractionated heparin dosing significantly reduced the median time to first therapeutic anti-Xa level by 5.3 hours compared to total body weight dosing in older and higher weight patients with venous thromboembolism.
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