GRADE Working Group grades of evidence
High quality (++++): Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality (+++O): Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality (++OO): 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 (+OOO): We are very uncertain about the estimate.

¹ Median reduction as observed across placebo groups in large osteoarthritis trials (see Methods section, Nuesch 2009c).
² Effect sizes were back‐transformed onto a 10‐cm VAS on the basis of a typical pooled SD of 2.5 cm in large trials that assessed pain using a VAS and expressed as change based on an assumed standardised reduction of 0.72 standard deviation units in the control group.

³ Percentage improvement was calculated based on median observed pain at baseline across control groups of large osteoarthritis trials of 6.1 cm on 10 cm VAS (Nuesch 2009c).

⁴ Downgraded (1 level) because it is unclear whether one of the two studies had a proper concealment of allocation, in both studies the analyses were not done according to the intention‐to‐treat principle, and one of the two studies had a restricted population of obese women, which hampers directness.

⁵ Effect sizes were back‐transformed onto a standardised WOMAC disability score ranging from 0 to 10 on the basis of a typical pooled SD of 2.1 in trials that assessed function using WOMAC disability scores and expressed as change based on an assumed standardised reduction of 0.58 standard deviation units in the control group.

⁶ Percentage of improvement was calculated based on median observed WOMAC function scores at baseline across control groups of large osteoarthritis trials of 5.6 units (Nuesch 2009c).

⁷ Downgraded (1 level) because it is unclear whether the study had a proper concealment of allocation, and because the study had a restricted population of obese women, which hampers directness.

⁸ Median control risk across placebo groups in large osteoarthritis trials (see Methods section, Nuesch 2009c).

⁹ Downgraded (2 levels) because it is unclear whether one of the two studies had a proper concealment of allocation, estimates are imprecise with confidence intervals including negligible and appreciable effects, and one of the two studies had a restricted population of obese women, which hampers directness.