Table 1.
Level I | Strong | Evidence obtained from multiple relevant high-quality RCTs |
Level II | Moderate | Evidence obtained from at least one relevant high-quality RCT or multiple relevant moderate- or low-quality RCTs |
Level III | Fair | Evidence obtained from at least one relevant moderate- or low-quality RCT with multiple relevant observational studies or Evidence obtained from at least one relevant high-quality nonrandomized trial or observational study with multiple moderate- or low-quality observational studies |
Level IV | Limited | Evidence obtained from multiple moderate- or low-quality relevant observational studies |
Level V | Consensus based | Opinion or consensus of large group of clinicians and/or scientists |
Adapted from Manchikanti L, Falco FJE, Benyamin RM, Kaye AD, Boswell MV, Hirsch JA. A modified approach to grading of evidence. Pain Physician 2014; 17:E319-E325 (6).