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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.

Calculate Your NNTUse the calculator below to check your health metrics

Why This Health Metric Matters

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.

  • ●NNT 1-10: very effective
  • ●NNT 10-50: moderate benefit
  • ●NNT >100: limited effectiveness
Sources:Cochrane Collaboration

Sample Clinical Scenarios

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⚠️ Antibiotic Side Effects

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Enter Clinical Data

⚠️For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.

🏥 Health Facts

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Key metric for evidence-based medicine

— Clinical

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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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