We all know that most medical treatments have potential side effects, some more than others of course. But it can be difficult to break down and conceptualize the numbers as far as determining if certain therapies will do more harm than good.
That’s where Number Needed to Treat, or N.N.T. and Number Needed to Harm N.N.H. statistics are of service. Basically it’s a determination of how many people would need to receive a medical therapy before one person would benefit, and on the other end of the spectrum, who would suffer from a side effect.
The New York Times broke down some examples and went into detail on the subject. Aspirin is a good example because many people take it regularly in an attempt to prevent a heart attack, but many people also can suffer from side effects like major bleeding.
The N.N.T. for aspirin to prevent one additional heart attack over two years is 2,000. (2,000 people take it, one heart attack is prevented.) That’s a pretty small percent. On the flip side, for every 3,333 people, just over two on average will have a major bleeding event, whether they take aspirin or not.
The Times put together some graphics that help see the big picture:
The percentages are small on both sides, but sometimes amount of harm potential is higher than the benefit, which became apparent with mammograms.
“If you look at the data for all randomized controlled trials of breast cancer screening, the N.N.T. for recommending screening to prevent one death from breast cancer after 13 years of follow-up is 1,477. But further analyses show that the one woman would have probably died of other causes anyway. There may be no benefit at all with respect to preventing death from all causes.
Screening with mammograms can cause harm, though. They lead to overdiagnosis, encouraging the provision of therapies that provide no benefits — but do carry risks, and therefore are considered harms.”
A Deep-dive Into Specialty Pharma
A specialty drug is a class of prescription medications used to treat complex, chronic or rare medical conditions. Although this classification was originally intended to define the treatment of rare, also termed “orphan” diseases, affecting fewer than 200,000 people in the US, more recently, specialty drugs have emerged as the cornerstone of treatment for chronic and complex diseases such as cancer, autoimmune conditions, diabetes, hepatitis C, and HIV/AIDS.
Another graphic:
So only one woman actually benefits compared to the many who have some sort of bad outcome. It’s fascinating to look at these numbers and consider when it is or isn’t worth it to seek medical therapy. Again, with these cases the percentages are small and we have no idea if we’ll be the one person. But it can be worth looking into with certain treatments.
