Do you know about the number needed to treat?
The world of medical stats is just as confusing – and seductive – as political stats. The raw value of a stat is often left out of the equation.
For example, a study of 1,000 people finds that 6 people get a particular cancer and 4 of them die. Taking drug A as opposed to old drug B reduces that number from 4 to 3. 1/6 = roughly 16%. Since 15% is the benchmark of statistical significance in science (and many disciplines), the study can promote the finding that deaths are significantly reduced with new drug A. Never mind that the news is irrelevant for 994 study participants and in real numbers, we’re talking about one person.
I believe even one person is certainly worth saving, but I use this example to highlight a very real problem with statistics. It’s all in your perspective, and when you view new drugs from a less popular statistic – the number needed to treat, or NNT – the picture sometimes changes.
To use a real-world example I recently read in Time magazine, let’s look at statins. Statins have become a commonplace Rx for the post-40 crowd, and they’re especially popular for men. (By the way, this gender skewing is something I have a problem with, as just as many women have cardiovascular health issues and 1 in 3 women – period – die from heart disease.)
Statins are used to reduce bad cholesterol, in the hopes that heart disease and subsequent heart attacks will be prevented. We’ve all seen the “30% reduced risk” in statin ads. But this isn’t 30% across the board – although that’s the perception and that’s why everyone’s on statins. Enter NNT.
This 30% number is the number of people in one of the study’s control groups (there’s a statin-taking group and a placebo-taking group). Moreover, this is 30% in real numbers – meaning, of men who would have had the heart attacks anyway (a very small number), that number was reduced by 30%. It’s not a 30% reduction in total.
But millions of men are taking statins. To prevent one heart attack, thousands of men who likely wouldn’t have a heart attack are taking statins. This is the number needed to treat. According to Time, 50 people have to take this drug to stop one heart attack (which, as Time points out, is not likely to be fatal). That’s 50 people needlessly popping a daily pill with untold side effects. Now, of those 50 people taking a drug to stop one heart attack that probably won’t be fatal, I wonder how many face serious, expensive and possibly life-threatening health problems.
Of course, on the scale of the total population, 50:1 becomes many thousands of heart attacks prevented – but many hundreds of thousands facing unnecessary and dangerous side effects (and spending a lot of extra cash).
That’s NNT, and that’s the true measure of a drug’s effectiveness and value.
Most Popular Posts
Worker Bees’ Daily Bites
Today’s news includes the return of a psuedo-scandal, proof that the FDA doesn’t care about women, and…donuts.
No, Vitamins Will not Kill You
It’s all over the news: vitamins will kill you! This is the same old scare that gets trucked out whenever there’s an FDA or Big Pharma scandal (it happened during the Vioxx debacle and again when the FDA got slammed last month). In fact, Elliott notes that there was a virtually identical story in January, and several last year…and the year before that. Each time, the same studies are brought up.
Honestly, the deja vu is annoying, so we don’t want to spend a lot of time on this pseudo scandal, but if you have any specific questions, feel free to shoot the Big Guy (that’s Sisson) a line. Simply click up yonder.
Vitamin A: it’s not an antioxidant, but people often misunderstand it to be one. No one thinks high levels of pure A is a good idea, and most high-potency vitamins that include high levels of A are giving you beta carotene, not pure A (the best multis will give you mixed carotenoids). For the record, the study that showed risk was done on smokers who were very, very sick.
In fact, this “news” out today is bandying the same old meta-analysis of many studies. Um, huh? you ask.
A quick lesson: “meta-analysis” is just a fancy way of saying “we looked at a bunch of different studies and here’s our opinion.” It’s not the best way to conduct a study, because it’s not really a study, per se – it’s an analysis of many studies which, in this case, were all conducted via different methodologies.
What’s more, in this particular case, many of the studies were based on questionnaires. If you’ve ever filled out a form detailing your caloric intake, exercise habits or sex life, you know these things aren’t exactly 100% accurate.
Here’s the sting: the majority of the studies included in ole Dansk’s report are outdated, ignore other, better studies, and generally involved really sick, elderly, even terminally ill patients.
As far as vitamin E is concerned, scientists continually scratch their heads at this Denmark meta-baloney (yeah, Denmark again…). We already know that the E in question isn’t the best for you. That’s been known for a long time. E, like the B vitamins, is really a spectrum supplement – there are eight different E’s, known collectively as tocotrienols and tocopherols.
Taking one tocopherol – the kind you’ll find in those cheap gel caps everywhere – is not a good idea and this has been known for quite a while now (and any multivitamin that uses this single form is not a multi you want to buy). The full spectrum E? Hundreds of rigorously conducted studies show proven benefits.
In short, don’t buy into the vitamin hype. The study is not news. It’s a review of studies that were conducted under inconsistent and varying conditions, on generally sick people. And it comes at time when the FDA and the drug companies are scrambling to improve their images.
Mark will be adding his thorough explanation to the Health Q&A this week, so we’ll give you the heads-up. Stick around, Apples.
The FDA Is Worse Than Your Ex
Indisputable facts: The FDA puts political pressure on its researchers. The FDA is a cushy landing pad for stressed-out former Pharma execs. The FDA tends to approve drugs based on drug companies’ own studies.
Jen and Sara report: Not only is the FDA corrupt, incompetent, and slow to change – evidently, we can now add sexist to the list.
We’re Waiting for the One with Omega-3′s
Cut the fat with these bloggers as your guides. Though we can’t condone every health tip offered by these ever-slimming scribes, the will of these bloggers to lose weight is inspirational and noteworthy. Check out these blogs and then head down your own obesity-free path to well-being.
Kevin Graves is sick of being fat. With age 50 fast approaching, Kevin has made an oath to get healthy before it is too late.
After six years of learning how to eat smart and love exercise, Shauna has lost over 170 pounds.
Donna’s goal is to regain her pre-grad school body before she graduates this May. Can she do it?!
JuJu and Jane have a lot of advice to give. After years of Yo-Yo dieting they lost a combined 375 lbs. by adopting smart habits and making health their number one priority.
The title says it all.
Not simply a personal account and a lot more than just low-carb living – Jimmy Moore’s blog chronicles his loss of more than 200 pounds and offers words of encouragement to anyone trying to do the same.
Stats, graphs, pics and video posts help you follow Renee as she tries anything to get fit.
As you may know by now, I am not afraid of the sunlight. Although most dermatologists suggest that we might be better off living in caves and covering ourselves head-to-toe whenever we venture out, my own evolutionary perspective leads me to believe we were designed to get sunlight almost every day and that our health suffers if we don’t get enough.
In fact, recent studies show that, as a result of our shunning the sun, many of us suffer from Vitamin D deficiency and a resulting loss of bone density and immune function (to name a few effects). Some researchers opine that more people die from lack of sun than from too much sun! But, I digress.
I came across an article the other day that piqued my curiosity since it dealt with the combination of running and sunning.
It basically showed that marathoners (of which I was once one) tend to get skin cancer at higher rates than other people. The more they ran, the higher the incidence of skin cancer. My take on what’s happening is that not only are the runners exposed to more sun (which can cause DNA damage in skin cells leading to cancer), but they are also bathed in more free radicals overall from the excessive oxidation of glucose and fats. We know that sun exposure does deplete the skin of the antioxidant Vitamin C.
Moreover, the act of running tends to divert blood flow away from the skin, starving it of additional important antioxidants that could neutralize the free-radical damage in the skin tissues. Add to that the enormous amounts of cortisol marathoners pump out doing this unnaturally high steady-state oxidative work and we not only get the DNA damage, we get the immuno-suppressive effects of the high-stress activity.
So: more DNA damage and a reduced ability to recognize that damage and take steps to eliminate those cells and/or repair the damage. That’s one reason (among many) that I have doused myself with antioxidants inside and out for over 20 years now. That’s also why one of my newest mantras is: a little running is OK – a lot is bad.
This article also brings up other points of discussion, such as whether the reliance on inferior sunscreens was another cause. It appears that for the past 30 years so-called sunscreens have been good at blocking UVB rays (the ones that burn) but not UVA (the ones primarily responsible for DNA damage and skin cancer). The effect is a generation of gung-ho health fanatics (yes, I was one) slathering on sunscreen and running 40, 50 or 100 miles a week. The fact that we didn’t burn only lead us to believe we could stay out even longer. Little did we know that the burning of skin might have been a great first warning to get the hell out of the sun.
Unfortunately, the sunscreen gave us the false notion we were invulnerable. More on that later….
© 2013 Mark's Daily Apple | Design By The Blog Studio