# Evaluation of unfractionated heparin therapy for venous thromboembolism using adjusted body weight in elderly or higher weight patients

## TL;DR

This study found that using adjusted body weight for heparin dosing in elderly or heavier patients leads to faster achievement of therapeutic anticoagulation levels.

## Contribution

The study introduces adjusted body weight dosing as a more effective strategy for heparin therapy in elderly and higher weight patients with venous thromboembolism.

## Key findings

- Adjusted body weight dosing reduced time to therapeutic anti-Xa levels compared to total body weight dosing.
- The benefit was most pronounced in patients aged ≥65 years and those receiving a bolus dose.
- Higher body weight patients under 65 years did not show a significant difference in time to therapeutic levels.

## Abstract

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.

The online version contains supplementary material available at 10.1007/s11239-024-03060-4.