Evidence-Based Surgery

Evidence-Based Surgery - Pillar Power

• Evidence-Based Medicine (EBM): Integrating best research evidence, clinical expertise, and patient values.
• Evidence-Based Surgery (EBS): Applying EBM principles to surgical practice.
• Goals: Improve patient outcomes, standardize care, inform policy, reduce costs, guide research.
• 📌 The 5 A's of EBS (Cyclical Process):
  • Ask: Formulate a clear, answerable clinical question.
  • Acquire: Systematically search for relevant evidence.
  • Appraise: Critically evaluate evidence for validity and usefulness.
  • Apply: Integrate appraised evidence with clinical expertise and patient values.
  • Assess/Audit: Evaluate outcomes and the EBS process itself.

⭐ The core principle of EBS is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual surgical patients.

Evidence-Based Surgery - PICO Sleuth

Formulating clinical questions: 📌 PICO framework.

• Patient/Problem/Population: e.g., Adults with uncomplicated acute appendicitis.
• Intervention: e.g., Laparoscopic appendectomy.
• Comparison: e.g., Open appendectomy.
• Outcome: e.g., ↓ Post-operative pain, ↓ length of hospital stay.

Example PICO: "In adult patients with inguinal hernia (P), is mesh repair (I) compared to non-mesh repair (C) more effective in reducing recurrence rates (O)?"

Sources of Evidence:

• Key Databases: PubMed/MEDLINE, Cochrane Library, EMBASE.
• Clinical Practice Guidelines (CPGs).

Basic Search Strategy:

• Use PICO terms as keywords.
• Combine with MeSH terms & Boolean operators (AND, OR).

⭐ A well-defined PICO question is crucial for efficient literature searching and retrieving relevant evidence.

Evidence-Based Surgery - Truth Tiers

• Hierarchy of Evidence (Top Tier First):

  • Systematic Review/Meta-analysis: Pooled data. Strength: High power. Weakness: Publication bias.

    ⭐ Systematic reviews and meta-analyses of high-quality RCTs are generally considered the highest level of evidence for therapeutic interventions.

  • RCT (Randomized Controlled Trial): Random allocation. Strength: Minimizes bias. Weakness: Costly, ethics.
  • Cohort Study: Observes groups over time. Strength: Incidence, risk. Weakness: Confounding.
  • Case-Control Study: Retrospective comparison. Strength: Rare diseases. Weakness: Recall bias.
  • Case Series/Report: Descriptive. Strength: Hypothesis generation. Weakness: No control.
  • Expert Opinion: Subjective. Lowest evidence.

• Critical Appraisal: Key aspects:

  • Validity: Sound design, bias control.
  • Reliability: Consistent results.
  • Applicability: Generalizable to patient.

• Common Surgical Biases:

  • Selection Bias: Non-random patient choice.
  • Performance Bias: Unequal care provided.
  • Detection Bias: Biased outcome assessment.
  • Attrition Bias: Differential dropout during follow-up.

Evidence-Based Surgery - Number Logic

• Relative Risk (RR): Risk_exposed / Risk_unexposed. RR<1: ↓risk with intervention.
• Odds Ratio (OR): Odds_exposed / Odds_unexposed. OR<1: ↓odds of event with intervention.
• Absolute Risk Reduction (ARR): Risk_control - Risk_treatment. True difference in risk.
• Relative Risk Reduction (RRR): ARR / Risk_control. Proportion of baseline risk removed by therapy.
• Number Needed to Treat (NNT): $NNT = 1/ARR$. Fewer patients treated for one to benefit is better.
• Number Needed to Harm (NNH): $NNH = 1/ARI$ (Absolute Risk Increase). More patients treated before one is harmed is better.
• Confidence Intervals (CI): Range of plausible values. 95% CI significant if it excludes 1 (for RR/OR) or 0 (for ARR/differences).
• p-value: Probability of observing effect by chance. Statistical significance typically if $p < extbf{0.05}$.
• Integration: EBS = Best Evidence + Clinical Expertise + Patient Values.
• Barriers: Lack of time, critical appraisal skills, resource access.

⭐ The Number Needed to Treat (NNT) is a highly intuitive measure for clinical decision-making, representing the number of patients one needs to treat with a specific intervention to prevent one additional adverse outcome.

High‑Yield Points - ⚡ Biggest Takeaways

• Evidence-Based Surgery (EBS) integrates best research evidence, clinical expertise, and patient values.
• PICO (Patient, Intervention, Comparison, Outcome) guides clinical question formulation.
• Systematic Reviews & Meta-analyses of RCTs provide the highest level of evidence.
• Randomized Controlled Trials (RCTs) are gold standard for evaluating interventions.
• Critical appraisal assesses validity and applicability of research findings.
• The GRADE system is used for assessing evidence quality and strength of recommendations.
• EBS aims to improve patient outcomes and reduce practice variations in surgery.