Number Needed to Treat (NNT)
NNT quantifies how many patients need treatment for one to benefit. It helps clinicians and patients understand treatment effectiveness in practical terms.
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NNT 1-10: very effective NNT 10-50: moderate benefit NNT >100: limited effectiveness
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Why: NNT translates clinical trial results into actionable numbers for shared decision-making.
How: NNT = 1 / ARR. Enter control and treatment event rates, or use RRR or raw counts.
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For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
🏥 Health Facts
Key metric for evidence-based medicine
— Clinical
Used in shared decision-making
— Guidelines
Understanding Number Needed to Treat
NNT is the number of patients who need to receive a treatment for one patient to benefit. It's a key measure in evidence-based medicine that helps quantify treatment effectiveness in practical terms.
NNT 1-10
Very effective treatment
- • Strong clinical benefit
- • Usually worth treating
- • High impact per patient
NNT 10-50
Moderately effective
- • Meaningful benefit
- • Consider patient factors
- • Weigh against side effects
NNT >100
Limited effectiveness
- • Small effect size
- • Target high-risk patients
- • Consider alternatives
Key Risk Measures Explained
Absolute Risk Reduction (ARR)
The actual difference in event rates between groups. Directly interpretable as the probability difference.
Relative Risk Reduction (RRR)
Proportional reduction in risk. Can be misleading without knowing baseline risk.
Number Needed to Treat (NNT)
How many patients need treatment for one to benefit. Lower is better.
Number Needed to Harm (NNH)
How many patients treated for one to experience an adverse event. Higher is better.
Using NNT in Clinical Practice
✓ Compare treatments for the same condition
✓ Inform shared decision-making with patients
✓ Allocate healthcare resources effectively
✓ Evaluate cost-effectiveness of interventions
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