Thursday, September 17, 2009
Patients who take the powerful new multiple sclerosis drug Tysabri are getting mixed messages about their risk of contracting a life threatening condition called progressive multifocal leukoencephalopathy, or PML. PML is a brain infection associated with the use of Tysabri. It appears that information regarding the level of the risk of PML given to patients on Tysabri depends on who they ask. As Keith Winstein of the Wall Street Journal reports:
Tysabri underscores a central mathematical issue in assessing risks and benefits of medical treatment -- one that has also shown up in calculating the risk of blood clots among heart-stent users, and in figuring out how beneficial chemotherapy is in treating lung cancer.
Simply put, the issue is a matter of whether to adjust for time. In other words, should the chances of contracting a harmful side effect be calculated by figuring out the simple percentage of all those taking the drug who have come down with the side effect? Or should those calculations be adjusted for the duration that patients have been treated?
The former method calculates what's called an "absolute" percentage. The latter, used widely in medical studies and by insurance actuaries, takes into account that risk changes over time: For example, someone who drives a car only one day during his lifetime is less likely to be in a crash than someone who drives for 20 years.
Using the absolute method, the manufactures of Tysabri report that the risk of PML is one in 8,700. The actuarial method results in a risk of one in 1,200 -- much closer to the one-in-1,000 threshold that may cause doctors to become more cautious in prescribing the drug.
The two mathematical methods in calculating risks have led to prior disputes. In 2006, Boston Scientific Corp. and Johnson & Johnson disagreed over whether their models of drug-coated heart stents -- tiny scaffolds that prop open clogged arteries -- caused blood clots years after implantation.
According to this WSJ article, J&J used the absolute method and reported no increase in the percentage of patients with clots in its coated stent. Boston Scientific applied the actuarial method and reported an increase in clots with the use of its stent. This led to an impression that J&J’s stent was safer than Boston Scientific's stent. The New England Journal of Medicine analyzed both stents with the same technique and discovered the same number of clots with both stents.
Similarly in 2005, a Canadian clinical trial inaugurated the use of chemotherapy to treat lung cancer after demonstrating that the treatment reduced mortality by 31%. Half the people in the study were given chemo, and half weren't.
But the results didn't mean that chemo decreased actual lung-cancer deaths -- only that it would extend the life of patients. In fact, after eight years, the study estimated that the same fraction of people would die with treatment as without -- about half. Since people on chemo lived longer, by about 21 months, the study could truthfully report that treatment reduced the average death rate during the study. (emphasis added).
As patients with chronic medical conditions are living much longer lives, it appears that long-term exposure levels as reflected in the actuarial model should be used to quantify the risks associated with treatment options so that both physicians and their patients can make informed treatment choices. [KVT]
Tuesday, September 15, 2009
Lifestyle Choices and Health: Your Social Life Can Impact Your Health And Your Food Choices Can Trump Your Genetic Code To Influence Your Weight
Two new studies came out this week that have interesting implications on the association between lifestyle choices and disease. The first is a study by Emily Sonestedt, a member of the Marju Orho-Melanders research group at Lund University Diabetes Centre published in the American Journal of Clinical Nutrition. This study deals with those who have the risk variant of the FTO gene. The FTO gene is the gene most commonly associated with overweight and obesity. Forty percent of the population have one copy of this gene. Seventeen percent have a double copy, acquired by inheriting one gene from each parent.
As ScienceDaily reports
[t]he risk of becoming obese is 2.5 times higher for those who have double copies of the best known risk gene for overweight and obesity. However, this is only true if fat consumption is high. A low fat diet neutralizes the harmful effects of the gene…. [In other words,] the risk of obesity was dramatically increased only in the case of high fat consumption.
The second is a study performed by the Universities of Exeter and Queensland, Australia published in the Scientific American Mind. This study reveals that the quality of an individual’s social life may have a greater role in health than diet and exercise. Simply being a part of a social group may significantly reduce both the risk of simple maladies, like the common cold, as well as devastating conditions such as stroke and dementia.
As reported in ScienceDaily, Professor Alex Haslam of the Psychology Department, University of Exeter, made the following comment on this study:
We are social animals who live and have evolved to live in social groups. Membership in groups, from football teams to book clubs and voluntary societies, gives us a sense of social identity. This is an indispensable part of who we are and what we need to be in order to lead rich and fulfilling lives. For this reason groups are central to mental functioning, health and well-being.
Monday, September 14, 2009
Food Safety News is the brain child of Bill Marler, a nationally recognized food safety and food borne illness expert. The first articles posted on the site suggest that this will be an excellent resource for those who are interested in food issues. As an example, read the posted article Food Safety Acts Compared: HR 2749 vs. S 510. For more, see Bill Marler Launches OnLine Newspaper, Food Safety News
Another high recommend goes to FoodSafety.gov which was created to be the “the gateway to food safety information provided by government agencies.”
The FoodSafety.gov website explains that:
[t]he federal government will enhance www.foodsafety.gov to better communicate information to the public and include an improved individual alert system allowing consumers to receive food safety information, such as notification of recalls. Agencies will also use social media to expand public communications.
Special features include advice on how to avoid food safety risks that occur more often at certain kinds of events and in certain seasons, how to avoid food safety risks that are higher for specific groups of people and how to locate a state agency in a particular area. KVT
Two Zambia air force members claim they were discriminated against when they were discharged because they have HIV.This African case may influence how African courts respond to the HIV epidemic and shape policy. Reports the Washington Post:
Across the continent, lawmakers are considering whether to make criminals of those who infect others with HIV, allow bosses to test workers for the virus, punish women who pass it to their babies and give constitutional protections to those with HIV.
Such questions are increasingly landing in courtrooms, presenting judges with cases that mix current science, individual rights and a devastating public health crisis. One, involving two Zambia air force members who say they were unfairly discharged because they have HIV, goes to trial here next month.
While the UN, human rights organizations and several African nations have favored a more rights-friendly approach for those with HIV, some African countries are justifying laws criminalizing HIV as a means to reduce the spread of the disease.
Laws criminalizing the transmission of HIV have been adopted from western to southern Africa, for example, with backing from some women's groups despite human rights advocates' contention that they deepen stigma. In Botswana, protests by activists have failed to stop employers from testing and excluding infected job applicants. A recent proposal in Rwanda would require HIV tests for many -- an idea supported by observers who say that relying on people to seek testing "can deprive other people of their right to life," as one University of Pretoria researcher wrote in South Africa's Star newspaper.