Core Curriculum
Module 8: Clinical Decision Making & Evidence‑Based Medicine
Core Topics
EBM steps, PICO, risk calculators, NNT adjustment, framing effects, GRADE, shared decision making — the practical application of research evidence to individual patient care.
📚 8.1 Applying Evidence to Patient Care
Evidence‑Based Medicine (EBM) integrates best research evidence with clinical expertise and patient values.
The PICO Framework
• Patient/Population
• Intervention
• Comparison
• Outcome
Five Steps of EBM
1. Ask (focused question)
2. Acquire (best evidence)
3. Appraise (validity)
4. Apply (to patient)
5. Assess (outcome)
Risk calculators (Framingham, ASCVD, CHA₂DS₂‑VASc) estimate individual baseline risk. Adjusted NNT: a patient’s NNT varies with baseline risk.
Adjusted NNT = Study NNT × (Study baseline risk / Patient baseline risk)
(Higher‑risk patient → lower NNT → more favorable benefit)
📌 Example: Study NNT = 100 at baseline risk 1%; patient baseline risk 5% → adjusted NNT = 100 × (1/5) = 20.
⚖️ 8.2 Risk‑Benefit Analysis & Communication
Comparing NNT and NNH
If NNT < NNH, benefits usually outweigh harms (but consider severity of outcomes).
Framing Effects
• Relative Risk Reduction (RRR) often sounds larger than Absolute Risk Reduction (ARR).
• Positive frame: “90% survival” vs. negative: “10% mortality” — same data, different perception.
Effective communication: Use natural frequencies (“10 out of 100 people”) and visual aids (pictographs, icon arrays).
📊 Example: RRR = 50% sounds dramatic, but if ARR = 1%, NNT = 100. Always present both relative and absolute measures.
📑 8.3 Synthesis of Evidence & Guidelines
Hierarchy of Evidence
1. SR/Meta‑analysis of RCTs
2. Individual RCTs
3. Cohort studies
4. Case‑control studies
5. Case series/reports, expert opinion
GRADE System
• Quality of Evidence: High, Moderate, Low, Very Low (downgraded for bias, inconsistency, imprecision)
• Strength of Recommendation: Strong or Weak
Clinical Practice Guidelines: Based on systematic reviews, disclose conflicts, updated regularly. They are recommendations, not mandates, and must be adapted to individual patient context.
🤝 8.4 Shared Decision Making (SDM)
SDM is the process where clinicians and patients reach a decision together, especially when benefits and harms are closely balanced.
- Decision aids: tools that help patients clarify values and understand options.
- Preference‑sensitive decisions: choices where the “right” option depends on individual values (e.g., PSA screening, breast cancer screening frequency).
📌 Key principle: “No decision about me, without me.” SDM improves patient satisfaction, knowledge, and adherence.