The committee focused on calibration data for the tools with the most evidence: ORBIT, HAS-BLED and ATRIA. The calibration evidence clearly suggested that ORBIT was more accurate than HAS-BLED and ATRIA at predicting absolute risk of major bleeding, both for people using vitamin K antagonists and those using direct-acting oral anticoagulants. Importantly, ORBIT was better calibrated at all levels of major bleeding risk, including higher levels. ORBIT was also better at predicting absolute risk of intracranial haemorrhage. The discrimination data showed little difference between tools in predicting major bleeding, with some outcome measures showing no difference and others showing a slight benefit for either ORBIT or HAS-BLED. Evidence showed that ORBIT had a significantly higher specificity and a slighter lower sensitivity than the other tools, but the committee agreed that the lower sensitivity would not be a drawback when used to inform discussions of risk. The committee agreed that the evidence overall, and particularly the calibration data demonstrating higher accuracy of absolute risk, strongly supported ORBIT as the tool of choice. The committee agreed that NICE's previous advice on monitoring and addressing modifiable risk factors was still relevant and added reversible causes of anaemia because it is a component of the ORBIT tool. How the recommendations might affect practice Use of the ORBIT score is a change in practice, which will take time to implement. The committee considered that the more accurate prediction of the absolute risk of bleeding is a real advantage in supporting patients and clinicians in shared decision making, which should lead to better clinical outcomes. The committee considered carefully a number of practical issues set out in this section. Overall, the committee concluded that this change is one that is worth making. 