Calculate relative risk reduction from control and treatment event rates.
Relative risk reduction is independent of baseline risk, so a 30 per cent reduction sounds identical whether the baseline is 20 per cent or 0.2 per cent. Absolute risk reduction and number needed to treat expose the difference. Reporting only relative reduction is the most common way trial results are made to sound more impressive than they are.
Relative Risk Reduction
RRR = (control rate − treatment rate) ÷ control rate; NNT = 100 ÷ absolute risk reduction
RRR = (control rate − treatment rate) ÷ control rate; NNT = 100 ÷ absolute risk reduction Relative risk reduction is independent of baseline risk, so a 30 per cent reduction sounds identical whether the baseline is 20 per cent or 0.2 per cent. Absolute risk reduction and number needed to treat expose the difference.
Reporting only relative reduction is the most common way trial results are made to sound more impressive than they are.
This calculator takes 3 inputs: Event rate in the control group, Event rate in the treatment group, Patients per group. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.