Evidence-Based Medicine (EBM)

Definition

Three pillars of EBM

1. Best available research evidence
   Evidence from systematic reviews, randomized trials, diagnostic studies, etc.
2. Clinical expertise
   Physician's skill, experience and clinical judgement.
3. Patient values and circumstances
   Preferences, affordability, adherence, comorbidities and social context.

EBM does not mean following research or guidelines blindly. It individualizes evidence to the patient.

Steps of EBM: The 5 A's

1. Ask - Formulate an answerable clinical question.
2. Acquire - Search for the best available evidence.
3. Appraise - Critically evaluate validity, importance and applicability.
4. Apply - Integrate evidence with expertise and patient preference.
5. Assess/Audit - Evaluate outcome and improve future practice.

Framing the Question: PICO

Hierarchy of Evidence

1. Systematic review and meta-analysis of randomized controlled trials (RCTs)
2. Individual RCT
3. Cohort study
4. Case-control study
5. Case series/case report
6. Expert opinion, basic science or mechanistic reasoning

Critical Appraisal of Evidence

1. Validity

• Was the study design appropriate?
• Was randomization and allocation concealment adequate?
• Were patients and assessors blinded?
• Was follow-up complete?
• Were important confounders controlled?

2. Results

• What is the magnitude of benefit or harm?
• Is the result statistically significant?
• Are confidence intervals narrow and clinically meaningful?

3. Applicability

• Is the study population similar to my patient?
• Are outcomes relevant to the patient?
• Is treatment feasible, safe and affordable?

Common Measures Used in EBM

• Relative risk (RR): Risk in exposed group/risk in control group.
• Odds ratio (OR): Odds of an outcome in one group compared with another.
• Absolute risk reduction (ARR): Difference in event rates between groups.
• Number needed to treat (NNT): Number treated to obtain one additional beneficial outcome.
  NNT = 1/ARR
• Number needed to harm (NNH): Number treated for one additional adverse effect.
• 95% confidence interval (CI): Range likely to contain the true result.
• p value: Probability that the observed result is due to chance. A p value <0.05 is conventionally considered statistically significant, but clinical relevance must also be assessed.

Importance in Dermatology

• Choose effective and safe therapy for psoriasis, atopic dermatitis, acne, urticaria and autoimmune blistering diseases.
• Compare conventional systemic agents with biologics and newer targeted therapies.
• Avoid ineffective, harmful or costly treatment.
• Use clinical guidelines rationally.
• Incorporate patient priorities, for example convenience, cost, cosmetic concerns, pregnancy plans and expected adherence.

Limitations of EBM

• Good-quality evidence may be unavailable, especially for rare dermatoses.
• Trial participants may not represent real-world patients.
• Publication bias and industry sponsorship may influence results.
• RCTs may have short follow-up and may miss rare adverse effects.
• Guidelines may become outdated.
• EBM cannot replace sound clinical judgement or patient-centered care.

Conclusion