Comparison of heparin assay monitoring protocols (CHAMP): study protocol for a pragmatic randomised trial

Due to widespread availability and familiarity, unfractionated heparin (UFH) is the most used intravenous anticoagulant for many indications in hospitalised patients. UFH, however, is a high-risk medication with complex pharmacokinetics and pharmacodynamics that are highly variable between different patients and within the same patients over time. The traditional titration and monitoring approach uses a clot-based assay, the activated partial thromboplastin time (aPTT), titrated to one and a half to two and a half times the upper limit of the normal range. Alternate assays indirectly measuring the anti-Xa level have not been compared with the aPTT for the monitoring of heparin in a prospective study. The optimal laboratory test for monitoring and adjusting heparin is not known. Our pragmatic study developed within the learning healthcare infrastructure is designed to answer this clinical question by comparing two established protocols for monitoring heparin in our hospital through a pragmatic randomised clinical trial.

The Comparison of Heparin Assay Monitoring Protocols (CHAMP) Trial is a single-centre, pragmatic, randomised trial conducted at Vanderbilt University Medical Centre (VUMC) beginning 26 June 2024. The CHAMP trial compares the aPTT protocol to the anti-Xa protocol for monitoring and titration of intravenous UFH for systemic anticoagulation in hospitalised adult patients. Admitted patients initiated on UFH protocols are assigned to either the aPTT or anti-Xa protocol in a randomised fashion. The primary outcome is time to reach the therapeutic anticoagulation range by coagulation assay. Secondary outcomes include the percent of measurements in the therapeutic range, the number of coagulation laboratory measurements over time, frequency of heparin rate changes while on the protocol and the incidence of thrombotic and clinically relevant bleeding events.

The CHAMP trial is an ongoing pragmatic trial embedded into the current existing clinical workflow for heparin administration. The two protocols are considered clinically equivalent and already used in clinical practice, allowing for a waiver of consent approval (VUMC Institutional Review Board #232192). This waiver is critical to the implementation of the study due to the nature of scenarios and time constraints in which UFH is typically initiated. Partnering with nursing, pharmacy and clinical providers has been key to launching this study, which provides the first prospective, randomised, direct comparison of the two heparin laboratory protocols available for the monitoring and titration of intravenous UFH in hospitalised patients. After trial completion and data analysis, the findings of the CHAMP trial will be submitted to a peer-reviewed journal for consideration of publication for distribution to a broad clinical audience.

The CHAMP study was registered on ClinicalTrials.gov (NCT identifier: NCT06329921) on 19 March 2024. The first patient was enrolled in the study on 26 June 2024, with enrolment of the planned 700 participants expected to occur over two years.