The herbal medicine Dan Shen, a standard treatment for ischemic stroke in China, lacks strong scientific evidence to support such use, according a new review of studies.
Nevertheless, based on the available data, Dan Shen treatment showed a tendency to improve short-term neurological deficits in stroke patients, say researchers at Sichuan University in Chengdu, China.
However, the short-term result “should be interpreted cautiously because of the poor methodological quality of included trials and the small numbers of patients,” said review co-author and neurology professor Ming Liu.
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.
Obstruction of a blood vessel supplying blood to the brain can result in ischemic stroke, which accounts for about 83 percent of all strokes.
In China, post-stroke use of herbal medicine is part of standard care in both Western-style hospitals and in traditional Chinese medicine hospitals. Dan Shen, in various pill, tablet and injection formulations, is the herb most commonly given for ischemic stroke; its use in that context spans more than three decades.
However, few researchers have tested the herb’s effectiveness in rigorous clinical trials that approach current international standards. The reviewers found six studies that met inclusion criteria for the review — randomized or quasi-randomized and controlled — involving 494 acute ischemic stroke patients.
The Cochrane reviewers found that methods of randomly assigning study subjects to Dan Shen or placebo were unclear, and that this could have led to results exaggerating a positive treatment effect by 30 percent to 41 percent. “It is therefore plausible that Dan Shen is truly ineffective and the apparent benefits are simply due to bias arising from the methodological weaknesses of the studies,” they say.
Since treatment and follow-up in these studies ranged from 14 to 28 days, it was not possible to assess the long-term effects of Dan Shen. “We found no evidence to support the routine use of Dan Shen agents for ischemic stroke,” Liu said. “However, if the apparently beneficial effects on neurological impairment were confirmed in methodologically rigorous trials, it would lead to a useful treatment for stroke being identified,” she added.
Ted Kaptchuck, O.M.D., associate professor of medicine at Harvard Medical School, said, “in Chinese society, at this time, basic science and laboratory evidence seems to be enough to gain widespread acceptance and adoption for the use herbal and other medications. In the West, we think it is a long shot to go from basic laboratory evidence to demonstrated clinical efficacy in randomized trials. We are not at the point where it is clear that a traditional Chinese herb has a major role in health care.”
Liu agreed: “The designs of these trials need to be improved in the future research, not only in the clinical trials on Dan Shen agents, but also in trials on other Chinese herbal medicine.”
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