An Australian research team is using artificial intelligence to improve the safe dosing of unfractionated heparin, a high-risk drug linked to serious side effects.


Unfractionated heparin (UFH) is an anticoagulant that is used to treat patients with a clot, such as a deep vein thrombosis (DVT). It is also used as a replacement for oral anticoagulants when they are suspended for major surgery.

The Princess Alexandra Hospital (PAH) is one of the largest surgical hospitals in Australia. It provides transplant, vascular, and major orthopaedic surgery procedures, which require extensive use of UFH, and where patients need the right dose quickly. However, UFH, despite being an old drug, has proven to be very difficult to dose, and the best method to do so remains elusive.

The traditional method to dose UFH uses a nomogram based on body weight to calculate a patient-specific dose, as well as determining when to take blood tests (best four to six hours after a dose). Testing is important to check if the dose results in the correct concentration in the blood, based on clotting time, to be effective (termed blood range). A high blood result means the patient may bleed, and a low blood result means the drug is not working. However, this old method does not help clinicians as much as they need. A local study showed that it took patients, on average, 35 hours to reach the right blood range. Ideally, it should be six to 12 hours.

The PAH introduced an electronic health record (EHR) in 2017, incorporating the dosing nomogram in a dedicated digital prescribing system. It was hoped this would improve dosing and blood monitoring. However, in practice, only 22% of patients reached the correct blood range after the first dose. Another local study found that implementing the digital nomogram did not improve UFH dosing or monitoring outcomes. This is unacceptable, and better methods are urgently needed. Our team has turned to AI.

UFH is commonly used in surgical hospitals like the PAH, however, dosing UFH is notoriously difficult

Machine learning (ML) is a subdiscipline of AI that uses computerised methods to identify patterns in data to develop a model or algorithm. For drugs like UFH, ML may be used to develop and operate a better method than the nomogram to calculate the best dose for a patient and prevent side effects. Yet, an international review found few ML studies for UFH, none of which had models that were suitable for hospital use.

Thus began a research initiative: to develop an ML model that predicts the blood range from a given dose of UFH. PAH formed a multidisciplinary team of hospital doctors, pharmacists with UFH expertise, and specialists in data management and AI. Over four years, the team gathered nearly 200 patient and drug variables that may influence dosing from approximately 2,500 patients. The resulting model was reasonably accurate, yet, according to local clinicians who tested the model, it was not practical enough to support dosing in hospital patients.

Based on this feedback, our team is undertaking a new project. First, more data has been obtained, now from 4,000 patients across five hospitals, to build a better model. Then the team will reverse the existing model so that it will estimate the optimal UFH dose required to achieve the target blood range, rather than predicting the blood result from a given dose.

The new model will be tested in a silent trial where AI dose estimations will be compared with those by clinicians using the nomogram method. If the ML model method proves to be more effective than the current method, our team plans to put the model in a user-friendly app for all clinicians in the future.

This work is a crucial step towards providing clinicians with real-time recommendations on the best UFH doses in a hospital, and we hope it will ultimately reduce side effects and patient harm. In addition, the AI models have shown us that UFH dosing cannot just be based on patient weight, as many patient and drug factors affect the dose. This is a real advantage of AI.

This research underscores a clear message: more sophisticated dosing strategies are essential to enhance the safety and effectiveness of care. Confronted with a medication whose complexities have challenged clinicians around the world for decades, AI offers a practical pathway to safer, more personalised treatment and a new frontier for pharmacovigilance in everyday clinical practice.

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