. 2018 Feb 22;2018(2):MR000013. doi: 10.1002/14651858.MR000013.pub6

Summary of findings for the main comparison. Open trial versus blinded trial.

Open RCT versus blinded RCT
Patient or population: individuals eligible for a trial  Settings: any  Intervention: open trial  Comparison: blinded, placebo trial
Outcomes	*Illustrative effects (95% CI)**		Relative effect  (95% CI)	No of participants  (studies)	Quality of the evidence  (GRADE)
	Effect with blinded trial	Effect with open trial
Number recruited	As measured^a		RR 1.25   (1.18 to 1.34)	4833  (2 studies)	⊕⊕⊕⊕  High
	41 per 100	50 per 100 (51 to 55)
	Low^b
	10 per 100	13 per 100  (12 to 13)
	Moderate^b
	30 per 100	38 per 100  (35 to 40)
	High^b
	50 per 100	63 per 100  (59 to 67)
The basis for the assumed risk* (e.g. the median control group risk across studies) is provided in footnotes. The effect for the open trial (and its 95% confidence interval) is based on the assumed risk in the the comparison group (blinded trial) and the relative effect of the intervention (and its 95% CI).  CI: confidence interval; RCT: randomised controlled trial; 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.

^aThis is the baseline recruitment measured in the studies presented in the 'Summary of findings' table.  ^bWe selected the low, moderate and high illustrative recruitment levels of 10%, 30% and 50% based on our prior experience with trial recruitment.