News - Mice are poor diabetic models


Analysis: Is coverage of Type 1 diabetes mice study justified? Some question quality of reporting on medical studies whose human impact is still unclear

By Amina Zafar.
CBC. 27 June 2011.

A study in which researchers at St. Michael's Hospital in Toronto managed to reverse Type 1 diabetes in mice grabbed headlines this week, but some have questioned whether the results of such animal studies, which may prove not to be applicable to humans, should be reported in the mainstream media at all.

It is not the first time that Type 1 diabetes has been reversed in mice. But in this latest study, Dr. Qinghua Wang in the hospital's division of endocrinology and metabolism, and Dr. Gerald Prud’homme, in the division of pathology, and their team were able to not just regenerate the insulin-secreting islet beta cells that are destroyed by the immune system because of diabetes, but also to stop the destruction of those cells.

Using a brain chemical called GABA that is produced by pancreatic beta cells and acts on the immune system itself, the researchers delivered a one-two punch to the disease. Until now, there had been no effective treatment that both regenerated and prevented the breakdown of beta
cells at the same time.

"In the present study, we demonstrated the therapeutic effects of GABA in the prevention and reversal of diabetes in Type 1 diabetes mouse models," the study's authors said in the June 27 online issue of the scientific journal Proceedings of the National Academy of Sciences .

Human implications far off

People with Type 1 diabetes are at high risk of kidney damage. They can develop vision problems that lead to blindness and nerve damage that requires amputations. Some who have difficulty controlling their blood sugars are at risk of death.

While the experimental findings of the GABA study seem promising, there is still a long road ahead to determine whether the method works — and is safe — in humans and has the potential to actually help those suffering from Type 1 diabetes. Michael Cloutier, president and CEO of the Canadian Diabetes Association, one of the funders of the study, is optimistic.

"Diabetes research such as this brings us closer to a cure," Cloutier said in a statement. "We are excited to be a part of this significant discovery and look forward to the outcomes of clinical studies." Researchers are striving to free people with Type 1 diabetes from the need for insulin injections. Matt York/Associated Press

But others caution against such bold claims.

"Clearly the findings are limited to mice and test-tube studies right now, and one must be very cautious in extrapolating what might happen in a mouse to what could happen in humans. But the possibility of islet proliferation and islet protection is potentially important," said Dr. James Shapiro, director of the clinical islet program and a professor of surgery, medicine and surgical oncology at the University of Alberta in Edmonton. Pancreatic islet cells include the subgroup of beta cells.

Shapiro developed and performs the Edmonton Protocol, which involves injecting islet cells into the liver of people with Type 1 diabetes. Some of the first patients he treated are still free of insulin more than a decade later. But for most, the effect fades over time and some need low-dose injections of insulin. Those long-term results are still an open question for the GABA hypothesis, which still needs to be tested in a human clinical trial.

Breakthroughs rare

Asking what the results of a medical study such as the one done by the researchers at St. Michael's mean for you personally is something producers and consumers of medical news don't do enough of, according to Dr. Andrew Oxman
and others who study medical research and reporting.

'There are breakthroughs, but they almost always take a long time.' — Dr. Andrew Oxman, Norwegian Directorate of Health and Social Welfare More often than not, mainstream media misrepresent the significance of medical studies and inflate their impact on human health, often simply by reporting on them at all, these critics say.

Contrary to what much of the reporting on medical studies would have the public believe, major medical breakthroughs that benefit people in a significant way are few and far between. "There are breakthroughs, but they almost always take a long time from a good idea based on what we know from basic science and previous research to testing them in enough people that we can be confident they do more good than harm," says Dr. Oxman of the health services research department at the Norwegian Directorate of Health and Social Welfare.

Oxman explored medical messages in the media in a study published in the journal Health

Expectations in 2003

As part of his research, Oxman and his co-authors surveyed medical reporters and did in-depth interviews with 10 journalists from Europe, Canada and Australia. Their aim was to identify the constraints that prevent journalists from improving the "informative value" of medical stories and to devise strategies for improving medical journalism. Oxman said informative reports about medical studies should provide valid and useful information that allows the public to draw conclusions about:

How applicable the information is to personal or policy decisions.

The strength of the evidence upon which the report is based or the degree of uncertainty.

The size of the effects, risks, associations or costs

Consumers of medical news should keep in mind that most treatments that do work have only modest effects, don't benefit everyone and even harm some of the people they are meant to help, Oxman said. In order to ensure treatments do more good than harm, large human clinical trials are needed.

In general, if a treatment sounds too good to be true, it probably is, said Oxman. Systematic research reviews (summaries of research evidence prepared using scientific methods) are often more informative and reliable than the latest "breakthrough" study hyped by drug companies, self-promoting researchers or universities or attention-seeking journalists, says Oxman.

Questions public should ask Dr. Jennifer Croswell, a medical officer on the preventive services task force at the U.S. Agency for Health-Care Research and Quality, a "breakthrough" is something that significantly improves the lives of patients. The discovery of penicillin or the first kidney transplants qualify, but most medical studies are far more incremental than that.

'News is a 24/7 cycle, but medicine and science moves a lot more slowly than that.'
— Dr. Jennifer Croswell, U.S. Agency for Healthcare Research and Quality"I think that news is a 24/7 cycle, but medicine and science moves a lot more slowly than that," said Croswell. "Most of the things that do get reported don't rise to that level."

Croswell suggested that people should be wary of bold headlines proclaiming a breakthrough discovery or cure and look for the intellectual or financial incentives behind such claims.

Other questions to ask, according to Croswell, are:
*   Was the trial done in animals or humans?
*   How many people were in the trial, and how many experienced positive outcomes?
*   What are the cautions and limitations of the study?
*   The findings of a study might be statistically significant but not clinically significant enough for a doctor or patient to change their behaviour based on the results. Some types of study design, such as a randomized control trial, are better suited to determining that.

However, there are times when lower-quality observational studies might be the only ethical way of investigating a particular problem. Studying the effects of secondhand smoke is one such example, says Croswell. Since it wouldn't be ethical to expose people to secondhand smoke as part of a study, researchers need to rely on observational studies to better understand its effects. The results of such studies, though flawed, might still be worth reporting in the mainstream media.

According to Karin Michels, a professor at Harvard Medical School and co-director of the obstetrics and gynecology epidemiology centre at Brigham and Women's Hospital in Boston, aside from asking how a study was conducted, the main question people should pose when consuming medical news is: What does the study mean for my own life?