Another study of 513 hospitalized people who had ultrasound exams for DVT found an incidence of 1.95 percent, the editorial noted. That four-times-higher incidence shows that the same criteria cannot be applied to both hospitalized and ambulatory patients, Livingston said.
The journal editors did a lot of talking before deciding that the paper should be run, he said. "We did a lot of analysis, looked at a lot of the literature," Livingston said. "Based on what I read, if you are ambulatory and have a low probability, with some leg pain, maybe a single ultrasound is good enough. The probability of having a DVT is low, and the test backs up your clinical suspicion. But a post-surgical or cancer patient who has a swollen leg, you would probably treat and look again, because the level of suspicion is high."
Treatment involves clot-preventing drugs, which carry their own danger of excess bleeding. The risk of such bleeding might be worth taking for someone in a hospital bed but not for an otherwise healthy person, Livingston said.
Beyond that, the lesson of the paper can be applied to all meta-analyses that lump together the results of different trials, he said. "It is a good platform to advise caution in judging all meta-analyses," Livingston said.
Averages derived by lumping many studies together can be deceptive, added editorial co-author Dr. Robert A. McNutt, a professor of medicine and chief of the section of patient safety research at Rush University Medical Center in Chicago.
"I prefer as a clinician to see the range of values across the studies rather than the average value of all the studies," McNutt said. "As a clinician, I look at the variability of patients, not the average value across the meta-analysis."
Controlled studies provide valuable evidence for medical practice, "but evidence-based medicine is
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