The One Medical Statistic You Need to Know
Every single recommendation you will ever get for health care — at least if it’s grounded in science, not fantasy — depends on numbers. How many people live, and how many people die, if they get Treatment A, and what difference if they get Treatment B? That’s what most medical researchers do: Count human lives and compare groups to see what works and what doesn’t work.
The trouble is that medical news is chock-a-block with intimidating numbers that are hard for a lay person to sort out. Worse, sometimes the sellers of new medical “breakthroughs” are actually trying to mislead and confuse you.
But now, we ride to the rescue with this: The One and Only Medical Statistic You’ll Ever Need. It’s called the Number Needed to Treat. This is a statistical idea that is simple and eye-opening. It will not only help you make truly intelligent health care decisions for yourself and your loved ones. It will also give you an idea of why American health care is so ruinously expensive. Read on for more.
“Number Needed to Treat:” The Simple Way to Understand What Works
How to Find the Number Needed to Treat for Just About Any Condition
To borrow a line from the late Steve Jobs, here is one “insanely great” website: TheNNT.com.
Aspirin’s NNT: It All Depends on the What-For
Take a look at the different NNT’s for using aspirin to treat or prevent heart attack. You can see the value all depends on how sick the patient is to start with, and what the drug is used for.
- Aspirin to treat heart attack: NNT = 42. A very good NNT, especially since we’re talking about administering a drug with a unit cost of maybe ten cents.
- Aspirin to prevent a second heart attack: NNT = 50. Another excellent NNT.
- Aspirin to prevent a first heart attack or stroke: NNT = 1,667. You see how much less bang for the buck you get when healthy people use drugs, even cheap ones like aspirin, to try to prevent disease. This is still a decent NNT for the price, as long as you’re not someone whose stomach bleeds from aspirin.
And here are a few more examples of NNT’s crunched by the physicians on this website:
- CT scans to screen high-risk smokers for lung cancer: NNT = 217
- Defibrillation for cardiac arrest: NNT = 2.5 (one of the best NNT’s out there, highly effective if done in time for an otherwise fatal condition)
- Coumadin to prevent stroke in someone with atrial fibrillation: NNT = 25
Some Eye-Popping NNT Numbers for Breast Cancer Screening
Pop quiz: What do you suppose is the Number Needed to Treat for mammograms for women in their 40s? In other words, how many 40-ish women do you think have to get mammograms to save one life? Is it:
The answer is “D” — more than 5,000 women in their 40s have to undergo mammograms to prevent a single breast cancer death. And the reason mammograms are controversial in this age group is not just the slim pickings in lives saved, but the many more women in this age group who are actively harmed by mammograms. They are subjected to biopsies, mastectomies, other cancer treatments and fear and anxiety because they receive a “false positive” test result that they may have cancer when they really don’t.
If a woman waits to age 50 to get breast cancer screening, the odds of saving a life improve — somewhat — to a NNT of 2,970. That’s because the older a woman gets, the greater the chances of getting breast cancer, and therefore the higher chance that the screening will catch something bad. The NNT is still not that great; that’s because breast cancer screening is a lot less beneficial than its advocates claim.
If you want to read the technicalities of how these NNT numbers for mammograms were calculated, click on this link. Table 2 is where you will find the key numbers.
Special caveat: These figures only apply to average risk women. Those with a family history of breast cancer or tested positive for the BRCA gene abnormality have a lot higher risk and therefore a lot more benefit from regular screening.
And that raises a key general point for disease screening tests: High risk people should worry and should get tested. Low risk folks — not so much. The numbers prove that the lower your risk is from the start, the less your chance of being helped by a screening test.
To your continued health!
Patrick Malone & Associates