GRADE evidence.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio.
GRADE Working Group grades of evidence. High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.
1Although the PONV results demonstrated significant heterogeneity (P = 0.003, I2 = 56%), it was partly explained by the dose of dexamethasone. 2Downgraded by not comparing higher dose with lower dose directly, but upgraded by the dose-response gradient. 3Although there was significant heterogeneity (P<0.00001, I2 = 94%), it was partly explained by the dose of dexamethasone. 4Publication bias as Pr>|z| = 0.06.
PONV: post-operative nausea and vomiting; VAS: visual analogue scales.
Patient or population: patients undergoing thyroidectomy. Settings: evidence from China, Japan, Korea, Italy, Switzerland, Norway, Portugal. Intervention: dexamethasone. Comparison: placebo.
GRADE evidence.