Table 2.

Custom system for assigning level of evidence and strength of recommendation8. From Bykerk, et al. J Rheumatol 2012; 39:xxxx; with permission.

Level of EvidenceStrength of Recommendation
IMetaanalyses, systematic reviews of RCT, or individual RCTAStrong recommendation:

  • Direct level I evidence

IIMetaanalysis, systemic reviews of observational studies (cohort/case control studies), or individual observational studies
OR
RCT subgroup/post hoc analyses		BModerate recommendation:

  • Direct level II evidence or extrapolated level I evidence

IIINonanalytic studies, e.g., case reports, case seriesCWeak recommendation:

  • Direct level III evidence or extrapolated level II evidence

IVExpert opinionDConsensus recommendation:

  • Expert opinion based on very limited evidence

NRRecommendations are not linked to evidence

  • RCT: randomized controlled trial; NR: not reported.