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NEW YORK (Reuters Health) - A new study adds a cynical note to the highly charged debate over Tasers, the American-made stun gun that has made its way quickly into law enforcement across the globe.
As it turns out, people looking to settle arguments about the weapon's safety may not get much help from scientists.
That's because the answer they get from published studies seems to depend on who paid for the research, according to a report in the American Heart Journal.
Looking at 50 human or animal studies on Taser safety, researchers found that 23 of them had been funded by the manufacturer, Taser International, Inc, or done by scientists with financial ties to the company.
Twenty-two of those studies, or 96 percent, concluded the stun guns were safe or at least unlikely to be harmful. By contrast, only about half of the research not linked to Taser International reached that conclusion.
"When you read articles that are very favorable to the device, invariably you will see that one of authors is affiliated with the company making Tasers or sitting on the board," said Dr. Byron K. Lee, who worked on the new study.
"I'm not necessarily saying the research is done dishonestly and they lied and twisted their conclusions, it could very well be they designed their research to give favorable results," added Lee, a cardiologist at the University of California, San Francisco.
According to the Scottsdale, Arizona-based company, its weapon has conquered the market rapidly, and is now used by law enforcement agencies in 107 countries.
With a pull of the trigger, two darts fly out of the gun and lodge in the skin or clothes of the target. The darts set up a high-voltage electric circuit that causes both sensory nerves and motor nerves to go haywire. The result is excruciating pain and violent muscle spasms that immobilize even the feistiest suspect.
NOT SO HARMLESS?
But critics say the powerful jolts, which in rare cases have caused broken bones, could also hijack the heart, causing it to enter a deadly flutter called ventricular fibrillation.
They worry particularly about the cases in which police have used the Taser on children and the elderly, as well as mentally ill people and drug addicts, who may be more vulnerable.
To dispel those fears, scientists have conducted scores of experiments, including an outlandish Taser-funded study published last year, in which sheep were doped up on methamphetamine and then shocked with a Taser X26 gun.
But the studies can't seem to agree.
"Both sides have research to back their claims that the Taser is safe or unsafe," Lee told Reuters Health.
If you Taser very close to the heart, he said, you might trigger a fatal heart rhythm in some animals. But if you aim further away, or use different animals, you might not.
Of course, Lee added, it is also possible that independent scientists might be biased toward finding harm.
"It is much more interesting to say that there is something wrong here, that there are harms," he explained.
When asked if that could have happened in his own study, he acknowledged that the researchers who rated the 50 articles knew where the funding for each had come from. Still, he said he felt their assessments would hold up to scrutiny.
ACCUSATIONS OF BIAS
Steve Tuttle, vice president of communications for Taser International, told Reuters Health that there was no bias in Taser-funded studies.
In an email, Tuttle argued that in most cases, there are three degrees of separation between the scientists doing Taser-backed research and the company.
"The doctors are only paid their normal salary for the research and receive no extra compensation and no moneys from TASER," he said.
"It is worth noting that Dr. Lee has been a paid expert in litigation against TASER and this fact is not mentioned in the conflict of interest section of this report," Tuttle added.
While acknowledging this, Lee countered that it was more than a year ago and that the journal did not require disclosures that far back.
He also said that after he started doing Taser research in 2008, he had removed himself from the case and paid back all the moneys he'd received.
Debates about conflicts of interest and corporate funding biasing research are nothing new, and happen throughout the medical community.
For instance, a study from 1998 in the Journal of the American Medical Association found that scientists from the tobacco industry rated secondhand smoking harmless more than 90 percent of the time. Only 13 percent of researchers without industry ties came to that conclusion, however.
"When you come to a research question with predetermined bias because of funding that you get, you can very much design a study to further the company's interests," Lee said. "I think that is a very real danger of biomedical research."
"The first step is to be aware of it, and then look really critically at the article's methods," Lee said.
SOURCE: bit.ly/qmmluq American Heart Journal, online August 10, 2011.