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Table 2 Quality assessment for studies assessing interventions

From: Mechanical CPR devices compared to manual CPR during out-of-hospital cardiac arrest and ambulance transport: a systematic review

LOE 1 Quality assessment for Randomized Controlled Trials
  The seven factors included as the relevant quality items for RCTs are:
  · Was the assignment of patients to treatment randomized?
  · Was the randomization list concealed?
  · Were all patients who entered the trial accounted for at its conclusion?
  · Were the patients analyzed in the groups to which they were randomized?
  · Were patients and clinicians "blinded" to which treatment was being received?
  · Aside from the experimental treatment, were the groups treated equally?
  · Were the groups similar at the start of the trial?
  Quality assessment for meta-analyses of RCTs
  The six factors included as the relevant quality items for meta-analyses are:
  · Were specific objectives of the review stated (based on a specific clinical question in which patient, intervention, comparator, outcome (PICO) were specified)
  · Was study design defined?
  · Were selection criteria stated for studies to be included (based on trial design and methodological quality)?
  · Were inclusive searches undertaken (using appropriately crafted search strategies)?
  · Were characteristics and methodological quality of each trial identified?
  · Were selection criteria applied and a log of excluded studies with reasons for exclusion reported?
LOE 2 Quality assessment for studies using concurrent controls without true randomization
  The four factors included as the relevant quality items for these studies are:
  · Were comparison groups clearly defined?
  · Were outcomes measured in the same (preferably blinded), objective way in both groups?
  · Were known confounders identified and appropriately controlled for?
  · Was follow-up of patients sufficiently long and complete?
  Quality assessment for meta-analyses of studies using concurrent controls without true randomization
  The six factors included as the relevant quality items for meta-analyses are:
  · Were specific objectives of the review stated (based on a specific clinical question in which patient, intervention, comparator, outcome (PICO) were specified)
  · Was study design defined?
  · Were selection criteria stated for studies to be included (based on trial design and methodological quality)?
  · Were inclusive searches undertaken (using appropriately crafted search strategies)?
  · Were characteristics and methodological quality of each trial identified?
  · Were selection criteria applied and a log of excluded studies with reasons for exclusion reported?
LOE 3 Quality assessment for studies using retrospective controls:
  The four factors included as the relevant quality items for these studies are:
  · Were comparison groups clearly defined?
  · Were outcomes measured in the same (preferably blinded), objective way in both groups?
  · Were known confounders identified and appropriately controlled for?
  · Was follow-up of patients sufficiently long and complete?
LOE 4 Quality assessment for case series
  The three factors included as the relevant quality items for these studies are:
  · Were outcomes measured in an objective way?
  · Were known confounders identified and appropriately controlled for?
  · Was follow-up of patients sufficiently long and complete?
LOE 5 Quality assessment for studies that are not directly related to the specific patient/population
  LOE 5 studies are those not directly related to the specific patient/population (e.g. different patient/population, animal models, mechanical models etc.), and should have their methodological quality allocated to the methodology of the study. The relevant quality criteria here are:
  · Good = randomized controlled trials (equivalent of LOE 1)
  · Fair = studies without randomized controls (equivalent of LOE 2–3)
  · Poor = studies without controls (equivalent of LOE 4).