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

Summary of findings 7. Financial incentive vs no incentive.

Financial incentive vs no incentive
Patient or population: individuals eligible for a trial  Settings: any  Intervention: financial incentive  Comparison: no incentive
Outcomes	*Illustrative comparative risks (95% CI)**		Relative effect  (95% CI)	No of participants  (studies)	Quality of the evidence  (GRADE)
	Effect with no incentive	Effect with financial incentive
Number recruited	As measured^a		RR 1.48   (0.85 to 2.58)	1506  (6 studies)	⊕⊕⊕⊝  Moderate^c
	9 per 100	13 per 100 (8 to 23)
	Low^b
	10 per 100	15 per 100  (9 to 26)
	Moderate^b
	30 per 100	44 per 100  (26 to 77)
	High^b
	50 per 100	74 per 100  (43 to 100)
The basis for the assumed risk* (e.g. the median control group risk across studies) is provided in footnotes. The effect with a financial incentive (and its 95% confidence interval) is based on the assumed risk in the comparison group (no incentive) 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.

^aThis is the baseline recruitment measured in the studies presented in the 'Summary of findings' table.  ^b We selected the low, moderate and high illustrative recruitment levels of 10%, 30% and 50% based on our prior experience with trial recruitment.  ^cWe downgraded 1 level for inconsistency. There was substantial heterogeneity, I² = 65%.