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Table 1 Level of evidence

From: Invasive ventilation modes in children: a systematic review and meta-analysis

Level Description of evidence
1++ High-quality meta-analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias
1+ Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias
1- Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias
2++ High-quality systematic reviews of case-control or cohort studies; or high-quality case-control or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal
2+ Well-conducted case-control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal
2- Case-control or cohort studies with a high risk of confounding, bias or chance, and a significant probability that the relationship is not causal
3 Non-analytic studies; for example, case reports, case series
4 Expert opinion
  1. RCT, randomized controlled trial.