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Level / Direction of Evidence
Appraisers use the following table to determine a Level of Evidence for each article they appraise:
Level of Evidence
Level I Evidence obtained from adequately powered & well designed randomized controlled trials (RCTs) on human (non-volunteer) participants, systematic reviews that contain majority RCTs, and meta-analyses. Post-hoc analysis of randomized data that maintains the integrity provided by the randomization.
Level II Evidence obtained from adequately powered non-randomized studies with a comparison group of human (non-volunteer) participants, or systematic reviews/meta-analyses of non-randomized studies with a comparison group.

Prospective or retrospective registry-type studies in which comparisons are made; cohort and case control studies are included here.
Level III Evidence from studies with no randomization and no comparison group, simulation/manikin studies.
Excluded from PEP Opinion articles, editorials, epidemiological reports, surveys, or articles not reporting primary studies. Animal studies are also excluded.
Direction of Evidence
Green Direction of results of this study are supportive for the use of this intervention
Yellow Direction of the results of this study are neutral for the use of this intervention
Red Direction of the results of this study oppose the use of this intervention
White Direction of results of this study are not yet evaluated
Note: When assigning DOE, appraisers must take into account how generalizable the study is to the North American EMS setting. This includes: level of training of the practitioners, setting in which the study was conducted and if the findings are expected to be similar to the EMS setting.
Critical Care Transport (CCT) is provided by a specially trained EMS teams, focused on the management and transport of critically ill patients. This level of care is often delivered in dedicated air medical or ground critical care transport units. CCT practitioners have ongoing specialized training, their scope of practice includes advanced interventions and medications and care delivery includes dedicated medical consult.
In PEP, certain interventions performed by CCT practitioners are designated 'CCT', to acknowledge the differences in applicability in Canadian EMS.
Primary Outcome
is what the researcher states they intended to measure (as opposed to results, which is what they found). PEP will document the primary outcome(s) listed in each study.
This information applies to the primary intervention of the study only. This stratification is meant to help differentiate patient related outcomes from process related outcomes. Decision makers may choose to give precedence to patient related evidence.
    Patient Related Outcome:
  • Any outcome that related directly to the patient's condition, recovery or deterioration. (e.g. survival, mortality, adverse event, ventilation, GCS, neurologic scale rating, infarct size, conversion, ROSC, O2 sats, ICP, pH, lab values, tidal volume, vital signs, symptoms, symptom scores, surrogate markers, patient safety)
    Process Related Outcome:
  • Any outcome related to the application of an intervention. (e.g. ease of use, time to access, DTB, prediction/identification, detection, LOS, efficacy, feasibility, CPR quality, time on scene, transport time, feasibility, provider safety)
This indicates the clinical setting in which the intervention was provided. This information is meant to aid in informing the reader about how direct and generalizable this evidence is to the EMS setting or their own setting of interest.