Table 1.

Qualitative modified approach to grading of evidence.

Level	Description
I	Evidence obtained from multiple relevant high quality randomized controlled trials
II	Evidence obtained from at least one relevant high quality randomized controlled trial or multiple relevant moderate or low quality randomized controlled trials
III	Evidence obtained from at least one relevant moderate or low quality randomized controlled trial 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
IV	Evidence obtained from multiple moderate or low quality relevant observational studies
V	Opinion or consensus of large group of clinicians and/or scientists

Source: [27].