Patients on long-term anti-coagulation therapy who test their own blood clotting time from home and continue to be managed by their GP are significantly less likely to experience a thromboembolic event, according to Oxford University researchers.

Point-of-care testing means patients can either adjust their own medication according to a pre-determined dose-INR schedule (self-management) or they can call into a clinic to be told the appropriate dose adjustment (self-monitoring).

In their Cochrane systematic review, the researchers looked at data from 28 randomised trials involving 8,950 participants carried out in 11 different countries that compared self-monitoring and self-management with standard monitoring. The results from 18 trials, which measured thrombo-embolic events, showed there was almost a halving of events with self-monitoring and self-management in comparison to standard monitoring.

The review also found reduced mortality in trials of patients who self-managed (but not in those who self-monitored) and no effect on major haemorrhage. However, data from recent studies show a beneficial effect of self-monitoring.

“There are more than 1.2 million people in the UK on warfarin therapy, of whom fewer than 2 per cent self-monitor their INR levels despite mounting evidence that self-monitoring alone can cut the risk of death by nearly two-fifths and more than halve the risk of strokes,” says lead author Professor Carl Heneghan, director of Oxford University’s Centre for Evidence-based Medicine in the Nuffield Department of Primary Care Health Sciences.

“Suitable patients still need to be identified and educated for self-monitoring as it is not feasible for everyone, but the evidence clearly demonstrates that self-monitoring can improve the quality of oral anticoagulation therapy and adds weight to the argument that more patients should be given the opportunity to benefit from this treatment approach.”

The researchers conclude that future studies should set out to understand in more detail why some people decide to use self-management – or not – and identify ways to improve its uptake and effectiveness.