Health

Statins unlikely to stem blood clots

Cholesterol-lowering statins may not prevent blood clots as thought, a new review suggests.

Cholesterol-lowering statins may not prevent blood clots as thought, a new review suggests.

It's been estimated that the statin rosuvastatin halved the risk of venous thromboembolic events such as deep venous thrombosis or DVT  — a blood clot in a vein deep in the body that can cause pain and swelling in a leg.

The previous suggestion of a large protective effect of statins on clotting events didn't hold up in a larger study. (Robert F. Bukaty/Associated Press)

That finding was based on a 2009 randomized controlled trial  involving 34 patients, called JUPITER. 

To look for evidence from more people, Kazem Rahimi from the George Centre for Healthcare Innovation at the University of Oxford in the UK and his co-authors combined the results of 29 published and unpublished randomized control trials involving more than 105,000 participants.

The researchers compared the effects of statins to controls and combed through mostly unpublished data on clotting events.

The difference in blood clot prevention could have happened by  chance alone, they concluded in Wednesday's issue of the journal PLOS Medicine, published by the Public Library of Science.

"The findings from this meta-analysis do not support the previous suggestion of a large protective effect of statins on venous thrombolytic events," the study's authors concluded.

"However, a more moderate reduction in risk up to about one-fifth cannot be ruled out."

Preventing DVT

The researchers found the events occurred in 465 patients or 0.9 per cent in the statin group compared with 521 or 1 per cent in the control group.

It's possible that the effect of statins was underestimated in the meta-analysis because of missing data or some other bias, the journals' editors said.

A journal commentary accompanying the study said that in 2008, the U.S. Surgeon General issued a "call to action" to increase awareness and to prevent deep vein thrombosis and pulmonary embolism, a life-threatening condition that occurs when a clot breaks off and travels to the lungs.

Using anticoagulants reduces the risk to nearly zero but the blood thinners can also cause bleeding, said commentator Frits Rosendaal of Leiden University Medical Center in The Netherlands.

"The association between statins and venous thrombosis in the methodologically strongest analysis shows at most a very small effect," Rosendaal said.

"If we do not wish to discard the possibility of a beneficial effect for the whole class, any such effects are limited to rosuvastatin."

The study received no specific grant from funding agents in the public, commercial or not-for-profit sectors.