Table 2 Hierarchy of evidence [18]
From: The Prevalence of low back pain in Africa: a systematic review
Level 1 | Meta-analysis of randomized controlled clinical trials |
Level 2a | One randomized controlled clinical trial (RCT) |
Level 2b | One non-randomized, or non-controlled, or non-blinded clinical trial |
Level 3 | Observational studies |
Level 4 | Pre-post test clinical trials |
Level 5 | Descriptive studies |
Level 6 | Anecdotal evidence |