Table 1.

Evidence quality rating

  • High-quality RCTs: High-quality includes good design, low risk of bias, and confidence in the estimate

  • Systematic reviews of high-quality RCTs

  • RCTs with important limitations: Limitations of RCTs could include inadequate power, poor follow-up, missing quality elements like allocation concealment, per-protocol analysis, etc

  • High-quality observational studies: High-quality observational studies typically include prospective cohort studies of large populations mirroring Canadian populations and adequate adjustment for confounding

  • Systematic reviews of RCTs with important limitations or high-quality observation studies

  • RCTs with profound limitations: Profound limitations in RCTs include those listed above but larger and multiple concerns (eg, a trial grossly underpowered for clinical outcomes, CIs that include meaningful harm and benefit, 50% loss to follow-up, etc)

  • Observational studies with important limitations: Observational studies with important limitations might include retrospective studies, small or specific subpopulations, high-risk confounding, etc

  • Other lower evidence studies like case series or studies without patient-oriented outcomes (physiologic studies)

  • Systematic reviews including any of these studies

  • RCT—randomized controlled trials.

  • Adapted from Stone et al.2