Doc, I Saw This Ad

CHW LogoAsk your doctor if MiracleCure™ is right for you!

We’ve all seen the ads for the latest pharmaceutical wonder.  Grimacing people, who presumably suffer from some sort of –itis or –osis, now able to play tennis or cuddle with grandchildren or sit in side-by-side outdoor bathtubs thanks to this amazing product.  There is then a rapid-fire list of potential side effects ranging from flatulence to hair loss to sudden death, followed by the concluding “Ask your doctor…”

How are you or your doctor supposed to know?

You need three basic pieces of information:

How well does it work?

How dangerous is it?

How much does it cost?

Some people who are given a medication will get better, and some won’t.  Similarly, some people will get better without any treatment, or with a different treatment.  If the number who improve with treatment is no bigger than the number who improve without, then the drug is useless and would be unlikely to be approved.  However, clinical trials may show that a drug is better than placebo or an alternative treatment, but the important question is how much better.  This can be summarized in a measure called the “number needed to treat (NNT).”  It quantifies how many people would need to be given a drug in order for one to be expected to benefit.  Let’s say MiracleCure is a new treatment for migraine.  In a clinical trial, 80% of subjects who received MiracleCure had a significant improvement in their headache.  That sounds really good.  But 75% of subjects who received WonderDrug™, a different migraine medication, also improved.  That difference was statistically significant, so it is a legitimate claim that MiracleCure is better than WonderDrug.  How much better?  You could say “a little,” but that is pretty subjective.   We can quantify it. The difference is 80%-75%, or 5%, which is 1 in 20.  Therefore, the NNT is 20, meaning 20 people would need to take MiracleCure instead of WonderDrug in order for one of them to see a benefit.

By itself, the NNT is a step in the right direction, but it’s incomplete to answer the question if it’s right for you.  If MiracleCure were not only better, but also cheaper and safer, than WonderDrug, the answer would be obvious.  But that is rarely the case.  New medications are usually more costly, and sometimes have different side effects.  For now, let’s just stick with the cost issue.  (Risks and side effects can be summarized by a similar number called the number needed to harm, perhaps the topic for a future column.)  Let’s say the newer, more expensive MiracleCure costs $500 per dose, while WonderDrug is $250.  Most people taking either one will get better; we’ve already determined that 20 people would have to take MiracleCure instead of WonderDrug for one of them to benefit.  In other words, 20 people would need to take a drug that costs $250 more, for a total cost difference of 20 times 250, or $5000.  That is the cost needed to treat.

Now, this actually is not quite so straightforward.  Your cost isn’t really $5000.  If you choose MiracleCure over WonderDrug, your cost will be $250 (the difference in price between them).  It’s essentially a $250 bet on a 1 in 20 chance of a benefit.  That can be hard to evaluate in the abstract.  Thinking of it as an overall expected cost of $5000 to achieve the benefit is a more concrete way to put it all together.

Then you can decide.  Is it worth $5000 for that extra shot at making your headache go away?  It may depend on how bad the headaches are, or exactly what symptoms you tend to get.  It may depend on the consequences: if the headache comes on the day before you are scheduled to deliver a major presentation, you may want to pay the extra money for the small additional chance that you’d be able to give the talk, whereas if you have nothing high stakes planned the next day, maybe you’ll take a chance on the slightly less effective drug.

The point is, it’s your decision.  The question shouldn’t be “Ask your doctor if MiracleCure is right for you,” but rather,  “Ask your doctor to help you decide if MiracleCure is right for you.”  And if you are going to make an informed decision, you now know the basic data to request.

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