April 11, 2024

Hierarchies of Evidence-based medicine are explained in the following figure.

The types of study include:

  • Case reports and case series
  • Cross-sectional studies
  • Case-control studies
  • Cohort studies
  • Randomized control trials (RCTs)
  • Systemic review and metaanalysis
Hierarchies of Evidence-based medicine

Level of evidence (Hierarchies of Evidence-based medicine)

1aSystemic review with homogeneity (SRwH) of RCTs
1bIndividual RCT with a narrow confidence interval
1cAll or none
2aSRwH of cohort studies
2bIndividual cohort study
2cOutcome research: ecological studies
3aSRwH of case-control studies
3bIndividual case-cohort studies
4Case series (Poor quality cohort and case-control)
5Expert opinion with/ without an explicit critical appraisal, or based on physiological, bench research, or first principles

See also: Recent advances in Orthopaedics