Uploaded March 2015 | Updated September 2026, 12 hours ago
According to an article published in the NY Times on February 2, 2015, far fewer people benefit from medical treatment than we're led to believe in advertisements such as direct to consumer ads, ads in medical journals, and even in medical journal articles. What they suggest should be done to clarify this problem is to express the number of people that need to be treated to obtain a drug benefit (NNT) as well as how many need to be treated to expose specific side effects (NNH, number of people needed to treat to cause a harmful side effect). Often times the NNT is well above 10 or even 100 and the NNH is much smaller.
The NNT for aspirin to prevent one heart attack over two years is 2,000. This means that less than 0.1% will benefit! Aspirin's NNH is 3,333 when it comes only to considering major bleeds such as a stroke, hemorrhage in the eye and GI bleeds. And this number does not include other dangers such as Reyes syndrome, anaphylactic shock, kidney damage, etc.
In the case of mammograms it takes 13 years of screening to prevent one cancer in 1,477 people! For every 333 women screened one extra will have a lumpectomy or mastectomy and for every 390 screenings one will undergo an unnecessary course of radiation. In addition, there will be one additional cancer caused by the radiation!
In the case of treating an ear infection with an antibiotic, we know that they don't prevent serious complications, reduce pain in the first 24 hours. However, one in 20 will have somewhat less pain from day 2-7 and one in 14 will develop nausea, vomiting, diarrhea, or a rash. The NNT is 20 and the NNH is 14.
According to an article published in the NY Times on February 2, 2015, far fewer people benefit from medical treatment than we're led to believe in advertisements such as direct to consumer ads, ads in medical journals, and even in medical journal articles. What they suggest should be done to clarify this problem is to express the number of people that need to be treated to obtain a drug benefit (NNT) as well as how many need to be treated to expose specific side effects (NNH, number of people needed to treat to cause a harmful side effect). Often times the NNT is well above 10 or even 100 and the NNH is much smaller.
The NNT for aspirin to prevent one heart attack over two years is 2,000. This means that less than 0.1% will benefit! Aspirin's NNH is 3,333 when it comes only to considering major bleeds such as a stroke, hemorrhage in the eye and GI bleeds. And this number does not include other dangers such as Reyes syndrome, anaphylactic shock, kidney damage, etc.
In the case of mammograms it takes 13 years of screening to prevent one cancer in 1,477 people! For every 333 women screened one extra will have a lumpectomy or mastectomy and for every 390 screenings one will undergo an unnecessary course of radiation. In addition, there will be one additional cancer caused by the radiation!
In the case of treating an ear infection with an antibiotic, we know that they don't prevent serious complications, reduce pain in the first 24 hours. However, one in 20 will have somewhat less pain from day 2-7 and one in 14 will develop nausea, vomiting, diarrhea, or a rash. The NNT is 20 and the NNH is 14.
