Number Needed to Treat (NNT) and Number Need to Harm (NNH)

Written By: 
Nicole Slater, PharmD Candidate

This informative tutorial describes two easy to calculate statistical tools - NNT and NNH - that help you analyze the results of clinical trials in a clinically meaningful way and help you make decisions based on benefit vs. risk.  The example given - the benefits and harms of clotostrapzin - is fictitious and merely intended to illustrate the concepts discussed.





I like how you presented the concept of NNT! I really like the graphics. One small suggestion -- the definition of NNT is the number of patients needed to be treated to prevent or cause one ADDITIONAL outcome (, since it compares event rates. The EER tells the number of people that need to be treated to prevent or cause one outcome. Another suggestion -- when calculating NNT or NNTH, rather than requiring users to convert the percentage into an absolute value, have people divide the ARR (as a percent) into 100. For example, your ARR is 16% -- dividing 16 into 100 can be done mentally and is easier than 1/0.16. Nice job! Allen