Quickly convert Odds Ratio (OR) to Number Needed to Treat (NNT) using our precise online calculator. Ideal for clinicians, researchers, and students, this tool simplifies understanding the practical impact of medical interventions. Just input the OR and Control Event Rate to get your NNT or NNH instantly.
Formula:
To convert an Odds Ratio (OR) to Number Needed to Treat (NNT), we first need the Control Event Rate (CER) and then calculate the Experimental Event Rate (EER) and Absolute Risk Reduction (ARR).
- CER: Control Event Rate (as a decimal, e.g., 0.15 for 15%)
- OR: Odds Ratio
The steps are as follows:
- Calculate Experimental Event Rate (EER):
EER = (OR × CER) / (1 - CER + OR × CER) - Calculate Absolute Risk Reduction (ARR):
ARR = CER - EER - Calculate Number Needed to Treat (NNT) or Harm (NNH):
NNT = 1 / ARR
(If ARR is positive, NNT applies. If ARR is negative, it indicates NNH - Number Needed to Harm. Both are typically rounded up to the nearest whole number.)