Patients on long-term anticoagulation therapy are incredibly less likely to experience a thromboembolic event, according to researchers at Oxford University. However, this only applies to the patients who test their own blood clotting at home and are managed by their GP.

Because of point-of-care testing, people on long-term oral anticoagulation therapy can monitor their own blood clotting time, which is determined by the international normalized ratio (INR). Patients can choose to adjust their own medication according to a pre-determined dose-INR schedule, or self-management. Patients also have the option to call a clinic and be told the appropriate dose adjustment, or self-monitoring.

In Oxford’s Cochrane systematic review, the researchers described the data from 28 randomized trials of 8,950 participants done in eleven different countries. The data compares self-monitoring and self-management with standard monitoring.

In the first 18 trials which measured thromboembolic events, the results displayed roughly a halving of thromboembolic events with self-monitoring and self-management as compared to standard monitoring. Additionally, the review found that decreased mortality in trials of self-managed patients, but not in those who self-monitored, had no effect on major hemorrhage. Despite this, recent studies showed a positive 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,” said the lead author Professor Carl Heneghan, Director of Oxford University’s Centre for Evidence-Based Medicine.

“Our review of the latest research finds that self-monitoring alone does indeed result in a statistically significant reduction in thromboembolic events, whereas our previous review did not find this effect.”

Necessary patients still need to be identified and educated for self-monitoring because it’s not feasible for everyone. However the evidence clearly shows that self-monitoring can improve the quality of oral anti-coagulation therapy. Ultimately, this data demonstrates that more patients “should be given the opportunity to benefit from this treatment approach,” explained Heneghan.

The above review was an update on a previous review performed by the same researchers in 2010. It includes 10 new studies of 4,227 participants, which strengthened the overall evidence.

The authors assert that future studies should essentially focus on why people decide to use self-management (or not) and identify ways to improve its effectiveness.