The Evidence for Nerve Repair in Obstetric Brachial Plexus Palsy Revisited

Table 1

Levels of evidence.

Level	Criteria
1	Systematic review of randomized trials or n-of-1 trials
2	Randomized trial or observational study with dramatic effect
3	Nonrandomized controlled cohort/follow-up study
4	Case-series, case-control studies, or historically controlled studies
5	Mechanism-based reasoning