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 | Â |
Moderate | Â | Â | Lack of agreement between studies (e.g. statistical heterogeneity between RCTs, conflicting results) | Â | Effect size more than 2 or less than 0.5 for all studies/meta-analyses included in comparison and significant | Â |
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 | Â |
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 | ┘ |