Comparison of a Fully Weight-Based Protocol with a Non-Weight-Based Dosage Titration Protocol for IV Unfractionated Heparin: A Before-and-After Study.

Background: Unfractionated heparin (UFH) is used for the prevention and treatment of arterial or venous thromboembolism. The dosage for IV infusion of UFH is generally based on the patient's weight, with adjustment to a specific target for activated partial thromboplastin time (aPTT). In May 2019, the UFH protocols at the study institution were changed from being fully weight-based (i.e., for both initial dosing and subsequent dosage titrations) to weight-based initial dosing and non-weight-based dosage titrations, but the relative effectiveness of these 2 approaches was not known.

Objectives: The primary objective was to compare the effectiveness in achieving therapeutic aPTT with the fully weight-based and non-weight-based dosage titration protocols. The secondary objective was to compare the effectiveness of the non-weight-based dosage titration protocol with that of the previous fully weight-based one for patients with low-target aPTT.

Methods: A single-centre, retrospective, observational before-and-after study was conducted for patients receiving therapeutic UFH for any indication. Patients in the "before" group (fully weight-based protocol) were treated from January 2015 to October 2016, and those in the "after" group (non-weight-based titration) from January to October 2020.

Results: From a total of 1969 charts screened, 137 patients treated according to the fully weight-based protocols and 130 patients treated according to the non-weight-based titration protocols were included. In terms of the co-primary objective, the median number of dosage adjustments to achieve therapeutic anticoagulation was 1 in both groups (p = 0.48), and the proportion of patients with therapeutic anticoagulation at 24 h was similar (96.2% [125/130] with the non-weight-based titration protocols versus 99.3% [136/137] with the fully weight-based protocols; p = 0.09). Among patients treated according to the low-target UFH protocols, those with the non-weight-based titration protocol were less likely to have therapeutic anticoagulation at first measurement of aPTT than those with the fully weight-based protocol (37.9% [25/66] versus 44.6% [41/92], p = 0.033).

Conclusions: This retrospective, observational, before-and-after study showed that the effectiveness of the non-weight-based dosage titration protocols in achieving therapeutic aPTT was similar to that of fully weight-based UFH protocols.