Lies and Damned Lies
The crucial health stat you've never heard of. By Darshak Sanghavi - Slate Magazine
If anything is supposed to be certain in medicine, it's that people with high cholesterol levels should be treated. But should they? Sifting through the underlying science reveals that the way in which scientists and drug companies describe the benefits of many medications—by framing the question in terms of "relative risks"—systematically inflates their value. The result is that patients frequently buy and consume medicines that do very little good. An alternative way of describing the benefits of medical therapy could help change that—if doctors and nurses would start using it.This is relative the absolute benefit is only 2.2%
Take cholesterol-lowering drugs. In 1995, the prestigious New England Journal of Medicine published a study strengthening the case that otherwise-healthy men with high cholesterol should take cholesterol-lowering drugs called statins. Researchers in Scotland reported a 31-percent reduction in the risk of heart attacks among men taking the statin pravastatin, sold by Bristol-Myers Squibb under the brand name Pravachol. Due in part to this study, Pravachol became one of Bristol-Myers' most profitable drugs and now grosses more than $2 billion in sales per year.
There's another instructive way to consider the numbers. Suppose that 100 people with high cholesterol levels took statins. Of them, 93 wouldn't have had heart attacks anyway. Five people have heart attacks despite taking Pravachol. Only the remaining two out of the original 100 avoided a heart attack by taking the daily pills. In the end, 100 people needed to be treated to avoid two heart attacks during the study period—so, the number of people who must get the treatment for a single person to benefit is 50. This is known as the "number needed to treat."
Developed by epidemiologists in 1988, the NNT was heralded as a new and objective tool to help patients make informed decisions. It avoids the confusing distinction between "relative" and "absolute" reduction of risk. The NNT is intuitive: To a savvy, healthy person with high cholesterol that didn't decrease with diet and exercise, a doctor could say, "A statin might help you, or it might not. Out of every 50 people who take them, one avoids getting a heart attack. On the other hand, that means 49 out of 50 people don't get much benefit."
But drug companies don't want people thinking that way; whenever possible, they frame discussions of drugs in terms of relative risk reduction. That's why the package insert for Pravachol highlights the 31 percent reduction and mentions the NNT not at all.
Comments
Hey Norm, love this site. Just not so sure about this article though…
The NNT is a well-recognized tool in quantifying the efficacy of a drug as utilized under a specific protocol, however, there is a small problem with its use – it is dependent on the frequency of the disease in the study population. If the disease in question in relatively rare, even in a high-risk population, then the NNT will undoubtedly be low. Using the provided example, even if statins were able to prevent 100% of otherwise inevitable heart attacks, the NNT would still be around 14. The relative risk avoids these issues, as it is independent of disease frequency.
What NNT is especially good for is helping to define the efficacy of current protocols for drug administration. If there are people being treated erroneously, then the NNT can help to identify such excesses, although the seriousness of the disease in question must also be taken into consideration. Sometimes, the NNT will be high, and there is simply no other choice but to continue treating in this manner, as overtreating may not be as serious as missing a small number of potentially preventable cases.
So, as far as a drug company printing relative risk as opposed to NNT in its product information is concerned, they are not necessarily lying. Of course they want to show statistics that make their drug look better, however, the relative risk is, for the most part, a more accurate measure of the direct efficacy of the drug.
This article and the NNT tool assumes everyone is at the same risk level. I am by no means a fan of big pharma and a proponent of govt. price controls. However, if you or a family member is in the highest risk stratum, I would take statins and any other medications doctors provide. It's true that statins may do significantly less for those with significantly less risk. But this tool is like saying, because cigarettes only increase incidence of cancer from around 1.3% to 2.4% (I made up these numbers but the percentages are of course small in both cases), it's ok for everyone to smoke.
Point taken. Your argument that:
It seems to me that depending on the cost of treatment and resources available to those needing treatment, age, and other factors, it might be reasonable to forgo treatment.
Post a comment