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Testing for inherited thrombophilias in stroke patients not warranted

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – The common practice of routinely testing patients with ischemic stroke for inherited thrombophilias can do more harm than good, according to a new report. Even if found, there is very little evidence to connect inherited thrombophilias to stroke, but an assumption of causality could lead to unnecessary long-term anticoagulation, the researchers say.

Contrary to authoritative recommendations, “many books and articles continue to perpetuate the need to order these tests as part of the stroke work-up, especially in the young,” write Dr. Jane G. Morris at the University of Massachusetts in Worcester and colleagues in the December issue of Stroke, published online October 14,.

They explain that while hereditary thrombophilias are known to predispose to venous thromboembolism, data linking them to arterial stroke are limited. To investigate further, the authors reviewed the medical literature on the topic.

They found that among six case-control studies looking at protein C deficiency, protein S deficiency, and antithrombin deficiency, none uncovered any statistical difference in prevalence of these disorders between patients with ischemic stroke and controls.

The team identified sixteen other case-control studies that examined factor V Leiden or prothrombin gene mutation in stroke patients younger than 60. Except for two “clear outliers,” the researchers report, the majority of these studies “do not support any association between the inherited thrombophilias and stroke.”

The cost of an inherited thrombophilia work-up is close to $1000, Dr. Morris and colleagues note, and this is often borne by the patients. They calculate that if anticoagulation is prescribed, the cost over a lifetime of, say, a 35-year-old patient would be about $18,000.

That excludes the costs of bleeding complications. “Over the next 45 years, this person has a 2.7% chance of a fatal bleed, a 13.5% of a major bleed, and a 100% chance of multiple minor bleeding complications, which would increase the cost substantially.”

Meanwhile, any benefit of such a strategy is unknown.

“We recommend that testing for inherited thrombophilias should be no different in the stroke population than in any other population,” Dr. Morris and colleagues conclude. That is to say, the decision should be based on accepted clinical features that suggest the need for a thrombophilic work-up: “history of an unprovoked VTE, VTE in an unusual location, family history of a VTE, thrombosis at a young age (younger than 45), and frequent thrombotic recurrences.”

Reference:

Testing for Inherited Thrombophilias in Arterial Stroke. Can It Cause More Harm Than Good?

Stroke 2010;41.