Inclusion Criteria

Basic criteria for original or review articles:

  • in English
  • about humans
  • about topics that are important to the clinical practice of medicine, nursing, rehabilitation, and other health professions, other than descriptive studies of prevalence
  • analysis of each article consistent with the study question.

Studies of prevention or treatment must meet these additional criteria:

  • random allocation of participants to comparison groups
  • ≥ 10 patients per group (assessed for outcome)
  • ≥ 1 specified outcome assessed in ≥ 80% of those randomized at ≥ 1 follow-up point
  • outcome measure of known or probable clinical importance
  • subgroup analyses must be preplanned, with groups analyzed as they were randomized; analysis must test for interaction between ≥ 2 subgroups.

Studies of diagnosis must meet these additional criteria:

  • inclusion of a spectrum of participants, all suspected of having the disease, with some, but not all, found to have the disease of interest after diagnostic testing
  • inclusion of ≥ 100 participants, with ≥ 50 participants with the disease and ≥ 50 participants without the disease
  • objective diagnostic ("gold") standard (e.g., laboratory test not requiring interpretation) OR current clinical standard for diagnosis (e.g., a venogram for deep venous thrombosis)
  • each participant must receive both the new test and some form of the diagnostic standard
  • interpretation of diagnostic standard without knowledge of test result
  • interpretation of test without knowledge of diagnostic standard result
  • diagnostic test characteristics reported.
Diagnostic tests may also be tested in randomized trials, in which case the criteria for prevention or treatment apply.

Studies of prognosis must meet these additional criteria:

  • inception cohort of patients at a similar and early point in the course of a disease or condition, all initially free of the outcome of interest
  • prospective standardized data collection
  • follow-up of ≥ 80% of patients until the occurrence of a major study endpoint or to the end of the study.

Studies of clinical prediction guides must meet these additional criteria:

  • purpose is to validate or compare a rule/index/scale/model that combines ≥ 2 factors into some type of score/ranking that assigns individual patients to different levels of risk for a specific outcome (diagnosis, prognosis, treatment responsiveness) based on the presence/absence of these factors
  • data for the prediction guide must be available before data on the outcome that it is predicting
  • the guide must be generated in one or more sets of real (not hypothetical) patients (derivation or development cohort)
  • the guide must be validated in another set of real (not hypothetical) patients (validation cohort); internal bootstrapping is not acceptable as validation
    • studies validating a previously derived clinical prediction guide must provide a reference for derivation of the guide and must assess ≥ 1 of the outcomes assessed in the derivation cohort
    • prediction guides developed using individual patient data from > 1 study do not require separate validation
    • validation cohort must have > 80% follow-up (if reported or apparent)
  • study must provide information on how to apply the prediction guide in individual patients or cite a reference to this information.

Studies of etiology of harm from medical interventions must meet these additional criteria:

  • explicit purpose is to assess adverse effects of an intervention
  • prospective data collection with clearly identified concurrent comparison groups for those at risk for the outcome of interest
  • groups are matched or analyses adjusted to create comparable groups (e.g., quasi-randomized controlled trial, nonrandomized controlled trial, cohort study with case-by-case matching or statistical adjustment to create comparable groups, nested case-control study)
  • blinding (masking) of observers of outcomes to exposures (criterion assumed to be met if outcome is objective, e.g., all-cause mortality or objective test)
  • if harm reported, relative risk (RR) or hazard ratio (HR) or equivalent ≥ 2.0, with a lower 95% CI that excludes 1.5
  • if no harm reported, upper 95% CI of RR or HR or equivalent excludes 1.5.
Randomized controlled trials assessing adverse effects are evaluated using criteria for studies of prevention or treatment.

Studies of quality improvement or continuing education must meet these additional criteria:

  • random allocation of participants or units to comparison groups
  • ≥ 10 patients per group (assessed for outcome)
  • ≥ 1 specified outcome assessed in ≥ 80% of those randomized at ≥ 1 follow-up point
  • outcome measure of known or probable clinical or educational importance
  • subgroup analyses must be preplanned, with groups analyzed as they were randomized; analysis must test for interaction between ≥ 2 subgroups.

Studies of the economics of health care programs or interventions must meet these additional criteria:

  • alternate diagnostic or therapeutic services or quality improvement activities must be compared on the basis of both the outcomes produced (effectiveness) and resources consumed (costs) in real patients
  • evidence of both effectiveness and costs reported in a single randomized controlled trial that passes criteria for prevention or treatment
  • results must be presented in terms of the incremental or additional costs and outcomes of one intervention over another.

Systematic review articles must meet these additional criteria:

  • explicit statement of the clinical topic
  • identifiable description of the methods, including the databases searched and explicit inclusion and exclusion criteria for selecting articles for detailed review; reviews of prognosis must have "inception cohort" as an inclusion criterion and reviews of etiology of harm must have a summary HR or RR > 2 (with lower 95% CI > 1.5) for significant harm or HR or RR upper 95% CI < 1.5 if there are no significant effects
  • > 1 major database searched
  • number of articles retrieved/reviewed and the number passed/included must be reported.

Pooled original studies must meet these additional criteria:

  • analysis in which patient-level data are pooled from ≥ 2 studies/cohorts/sources to assess a question related to one of the study categories but article DOES NOT meet criteria for a systematic review.

Evidence-based guidelines must meet these additional criteria:

  • the Guideline must be based on a published systematic review that passes our current criteria for a Review
  • methods and findings of the systematic review may be reported within the Guideline document or in a separate document that accompanies the Guideline or is cited in the Guideline and is accessible
  • evidence underpinning the recommendations must be reported (e.g., citations of studies, estimates of effect, etc)
  • the strength of evidence (such as GRADE) for the recommendations must be reported.
Updated 1 February 2017