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Mountain View physician invents device for clearing up dangerous blood clots

Rating

2 Star

Mountain View physician invents device for clearing up dangerous blood clots

Our Review Summary

This story baldly misstates the evidence (or lack thereof) supporting the effectiveness of a device used to dissolve certain blood clots. Indeed, a careful reader would not even have to delve into the medical evidence to realize something is amiss. The story calls the Trellis Peripheral Infusion Device “life-saving,” effective, and safer and quicker than alternative therapies. However, it notes that only a handful of doctors across the country use the device (even though it has been on the market since 2005) and the clinician quoted in the story says he has used it on only eight patients, even though he sees more than 100 similar patients every year. A reader might well wonder, “If this device is so great, why do so few doctors use it and why do even those who do use it prefer to use different treatments for the overwhelming majority of their patients?” The story ignores that glaring inconsistency.

This story is also an extreme example of disease-mongering. It portrays deep vein thrombosis as a leading killer. However, not only is the death toll figure it uses taken from a misleading statement on a web site sponsored by a pharmaceutical company that sells drugs to treat the condition, the quoted number of deaths is 30 times the estimated toll listed in a recent report from the U.S. Surgeon General.

 

Why This Matters

When a story calls a treatment life-saving and effective, but fails to provide any hard numbers: watch out. When a story says a treatment is better than the alternatives, but also reveals that it is rarely used: watch out. When a story makes a treatment sound almost too good to be true… well, you know how to finish that sentence.

Criteria

Does the story adequately discuss the costs of the intervention?

Not Satisfactory

The story does not provide any cost information.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

As mentioned above, this story calls the Trellis device “life-saving” and effective, without providing any details about how the experiences of patients treated with this device compare to those of patients treated in other ways. Indeed, since the overwhelming majority of cases of deep vein thrombosis are not life-threatening, it is hard to see how it is appropriate to describe the device as “life-saving.” What’s more, the patient featured in this story is obviously unrepresentative of the typical patient with deep vein thrombosis. As the doctor who treated her notes, he sees more than a hundred patients a year with this problem and yet he has used the device only eight times. The anecdote presented is certainly unusual.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The only mention of potential harms is that the featured patient’s mother was concerned about the risks of using a new device; but the story goes on to say she is now a proponent of the device. The story does not make clear that although the technique is designed to minimize the patient’s exposure to clot dissolving drugs, there is still a potential risk of bleeding, including strokes. There is also no mention that an analysis of the manufacturer’s own data on patient experiences notes that three out of four patients required angioplasty and/or stent procedures in addition to the initial treatment with the new device, or that one out of six patients required another round of treatment. The American College of Chest Physicians guidelines report that this type of catheter-directed therapy is associated with similar rates of both success and problems with major bleeding as conventional treatment with clot-dissolving drugs.

In addition, there was a safety recall of a similar device in 2004.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

This story not only fails to provide readers with a summary of the evidence, it includes claims that conflict with reviews of the medical evidence.

The lead sentence of the story calls the Trellis Peripheral Infusion System a “life-saving device.” The story also describes the device and procedure as “safer and quicker” than alternative treatments. It also refers to the system’s “effectiveness.”

By contrast, the most recent guidelines from the American College of Chest Physicians (which were issued three years after the Trellis device went on the market) recommend against routine use of catheter-directed thrombolysis in patients with a blood clot in a vein in their arms, though the guidelines say this type of therapy may be used in certain high risk patients under certain conditions.

One recent review of treatments for deep vein thrombosis is far more cautious. It states that while the reported short-term outcomes of catheter-directed thrombolysis (which includes devices such as the Trellis system) are “encouraging in selected patients. Further evidence is required to establish long-term benefits and cost-effectiveness.” A systematic review of the evidence concerning thrombolysis for acute deep vein thrombosis updated by the Cochrane Collaboration earlier this year included catheter-directed thrombolysis as a topic for further research. In other words, contrary to the statements in this story, there is no widely accepted evidence of how this type of device compares to other therapies.

References:
http://atvb.ahajournals.org/cgi/content/abstract/30/4/669
(Arteriosclerosis, Thrombosis, and Vascular Biology. 2010;30:669.) © 2010 American Heart Association, Inc.
DVT: A New Era in Anticoagulant Therapy
Indications for Catheter-Directed Thrombolysis in the Management of Acute Proximal Deep Venous Thrombosis
Benjamin O. Patterson; Robert Hinchliffe; Ian M. Loftus; Matt M. Thompson; Peter J.E. Holt

http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD002783/frame.html
Watson L, Armon MP. Thrombolysis for acute deep vein thrombosis. Cochrane Database of Systematic Reviews 2004, Issue 3. Art. No.: CD002783. DOI: 10.1002/14651858.CD002783.pub2.

Does the story commit disease-mongering?

Not Satisfactory

The story states that “Deep venous thrombosis causes about 300,000 deaths annually in the United States.” But a report from the U.S. Surgeon General estimates the toll of deep vein thrombosis is closer to 100,000, mostly due to clots that travel to the lungs causing a pulmonary embolism.

The description of a 22 year old woman with her symptoms is also alarming. Her case is quite rare. Of 1,000 cases of deep vein thrombosis, only 10 to 40 involve the upper extremity or arm. And of those, just 2 to 10 of them involve a cervical rib, an extra rib bone that can interfere with blood flow in a way that in rare cases causes a clot. In summary, the alarming toll quoted in the story does not reflect the best available estimates and the featured patient represents an extremely rare case.

The story cites the Coalition to Prevent Deep-Vein Thrombosis as the source of the 300,000 deaths a year figure. That number is on the group’s web site, citing a research article. However, the article used as the source actually just cites another article that estimates that deep vein thrombosis may kill about 60,000 people a year in the U.S.

The story fails to point out that the remarkably high estimate comes from a group funded by a pharmaceutical company that lists thrombosis as a “key therapeutic area.” As the coalition web site points out: “The Coalition to Prevent Deep-Vein Thrombosis (DVT) is funded by sanofi-aventis U.S. LLC.”


References:

http://www.surgeongeneral.gov/topics/deepvein/calltoaction/call-to-action-on-dvt-2008.pdf See p. 9

Coalition to Prevent Deep-Vein Thrombosis
About DVT
http://www.preventdvt.org/about/what-is-dvt.aspx

Gerotziafas GT, Samama MM. Prophylaxis of venous thromboembolism medical patients. CurrOpin PulmMed. 2004; 10:356-365
http://journals.lww.com/co-pulmonarymedicine/pages/articleviewer.aspx?year=2004&issue=09000&article=00006&type=abstract

Does the story use independent sources and identify conflicts of interest?

Satisfactory

This story does note that one of the doctors quoted is the inventor of the device. It also includes comments from a clinician who appears to be an independent source.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

There are several alternative approaches to treat deep vein thrombosis, but this story fails to provide readers with a fair comparison. It states without evidence that this device is superior to the alternatives. It fails to mention that other catheter devices are available that are based on the same treatment concept as the Trellis device. What’s more, the story fails to note that treatment with the Trellis involves a powerful clot-dissolving (thrombolytic) drug that may be more likely to cause bleeding than alternative drug treatments. And it creates a misleading comparison by stating that the device is safer because it directs the drug to the specific location of the clot rather than exposing a patient’s entire body. That sort of systemic thrombolytic drug treatment is unusual. The more common treatment is to use the blood thinner heparin, not a thrombolytic drug.

Does the story establish the availability of the treatment/test/product/procedure?

Satisfactory

The story reports that only a handful of surgeons across the country have used the Trellis device, thus alerting readers that it is not widely available.

Does the story establish the true novelty of the approach?

Not Satisfactory

The story portrays the Trellis device as unique. It does not mention that there are other catheter-directed treatments in development or clinical use. In fact, in its application for FDA approval of this device, the company that sells it (Bacchus Vascular) described this Trellis device as “substantially equivalent to existing legally marketed devices.”

Does the story appear to rely solely or largely on a news release?

Not Applicable

We can’t be sure of the extent to which the story may have been influenced by a news release.

Total Score: 2 of 9 Satisfactory

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