Table 1

Grading of evidence sources and recommendations

Evidence or recommendationGrade
Evidence source as recommended by the Agency for Health Care Policy Research (AHCPR):
    Meta-analysis of randomised controlled trials (RCT)1a
    One or more RCT1b
    One or more controlled trials (without randomisation)2a
    Other well designed studies (quasiexperimental)2b
    Non-experimental studies (descriptive studies such as comparative or correlation studies, or case-control studies)3
    Expert committee opinions, clinical experience4
Preliminary recommendations for treatment of psoriatic arthritis (using the best available evidence extracted from published literature):
    Category 1 evidenceA
    Category 2 evidence, or extrapolation from category 1 evidenceB
    Category 3 evidence, or extrapolation from category 1 or 2 evidenceC
    Category 4 evidence or extrapolation from category 2 or 3 evidenceD