Skip to main content

Table 1 The features of evidence grading captured in a GRADE plot (adapted from Evid Based Med 2011;16:65-9)

From: Graphical displays for effective reporting of evidence quality tables in research syntheses

Grade Design Risk of bias Inconsistency Indirectness Effect size Evidence Quality
  Studies are either described as randomised-control trials (RCTs) or observational. Explains the limitations of the study based on assessment of blinding and allocation process, follow-up and withdrawals, scarcity of data, other methodological concerns e.g. incomplete reporting, subjective outcomes. Inconsistencies due to unexplained (statistical) heterogeneity. The same weakness is only downgraded once. Presence of indirectness in the PICO elements that affect the generalisability of participants and outcomes from each study to population of interest. Relates to imprecision of the estimated effect based on the reported odds ratios or relative risks or mean differences for comparison. This is based on the confidence intervals, sample size and number of events.  
High Randomised controlled trial No problems All/most studies show similar results with or inconsistency across studies is explained by a dose response Population and outcomes broadly generalisable Effect size more than 5 or less than 0.2 for all studies/meta-analyses included in comparison and significant  
Moderate    Lack of agreement between studies (e.g. statistical heterogeneity between RCTs, conflicting results)   Effect size more than 2 or less than 0.5 for all studies/meta-analyses included in comparison and significant  
Low/Very low Controlled observational study Problem with 2 or more elements Serious lack of agreement between studies Some problem with 2 or more elements Not all effect sizes more than 2 or less than 0.5 and significant; or if effects observed not significant  
Examplea: Thiamine vs Placebo for Pelvic Pain Randomised trial No limitations Consistent Indirect Precise Moderate
  Initially assigned a high strength level → No Change → No change → Relegation → No change
  1. abased on evidence profile shown in Fig. 1 and BMJ 2012;344:e3011 doi:10.1136/bmj.e3011