The National Institute for Health and Clinical Excellence (NICE) has asked Bayer for more evidence concerning the clinical and cost effectiveness of Xarelto (rivaroxaban) in the treatment of deep vein thrombosis (DVT).

NICE is currently appraising Xarelto for the treatment of DVT and prevention of recurrent DVT and pulmonary embolism (PE) following an acute DVT in adults. The request for more information is made in draft guidance issued today.

Treatments for VTE include initiation with anticoagulant drugs, such as low-molecular weight heparin - for example Sanofi's Lovenox (enoxaparin), the most commonly-used low-molecular weight heparin in the UK - unfractionated heparin or fondaparinux sodium. Treatment is then overlapped with a vitamin-K antagonist (VKA) such as warfarin until the oral blood thinner is effective and a proper dose is achieved.

The independent appraisal committee at NICE which is looking at Xarelto in this indication points to evidence from patient experts which stated that many patients find taking warfarin to be "a sources of stress," said Meindert Boysen, programme director for technology appraisals at NICE.  This is because it requires regular monitoring with blood tests and dosing adjustments, and for patients to be careful about their diet because of warfarin's interaction with certain foods.

The expert patients' evidence also said that Xarelto "may be a useful alternative," he added.

However, the appraisal committee was unable to make a decision on the data presented by the manufacturer, because it felt that it had failed to demonstrate the drug's clinical and cost-effectiveness in the context of UK clinical practice.

"In particular, the committee was concerned that an analysis for patients who required treatment beyond 12 months was not presented, and noted the comments of clinical specialists to the effect that some people with DVT need to continue on anticoagulant therapy permanently," said Mr Boysen.

"The committee also noted subgroup analyses in the main clinical trial that suggested that there could be differences in the effectiveness of rivaroxaban between the groups that were assigned treatment durations of three, six and 12 months that it would wish to explore further. The committee has therefore requested further information from Bayer about the clinical and cost-effectiveness of rivaroxaban used as a long-term treatment, and has also asked for comment on the differences between the subgroups receiving different intended treatment-durations," he added.

The annual incidence of DVT in the general population varies considerably with age, ranging from one in 10,000 for people under 40 years of age to one in 100 for those aged over 80. People with a previous episode of VTE have a high (30%) chance of suffering a recurrence within eight years.

It is estimated that there will be over 46,000 cases of acute DVT in England and Wales during 2012, rising to nearly 50,000 by 2016 due to an increasing and ageing population, says NICE.

* Last month, the Scottish Medicines Consortium (SMC) published guidance on Xarelto's use in this indication. This states that the drug "has been shown to be non-inferior to standard anticoagulant therapy including a low-molecular weight heparin in combination with a vitamin K antagonist for the treatment of proximal DVT and prevention of recurrence."

However, it adds that experience with Xarelto in this indication for more than 12 months is “limited; therefore, the cost-effectiveness of indefinite treatment has not been demonstrated."