Table 1 Levels of evidence for primary research question on therapeutic studies
From: Level of evidence in wrist ligament repair and reconstruction research: a systematic review
Level I | High-quality RCT with statistically significant difference or no statistically significant difference but narrow confidence intervals. | Systematic review of level I RCTs (and study results were homogenous) |
Level II | Lesser-quality RCT (e.g. 80% follow up, no blinding, or improper randomization). Prospective comparative study. | Systematic review of level II studies or level I studies with inconsistent results. |
Level III | Case-control study. Retrospective comparative study. | |
Level IV | Case series. | |
Level V | Expert opinion. Case report. Technical report. |