Summary of findings 1. Action observation versus control: effect on upper limb rehabilitation after stroke.

Action observation versus control: effect on upper limb rehabilitation after stroke
Patient or population: upper limb rehabilitation after stroke Setting: hospital, clinic, research laboratory or home Intervention: action observation Comparison: control
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (trials)	Certainty of the evidence (GRADE)	Comments
	Risk with control	Risk with action observation
Arm function assessed by: Action Research Arm Test, Fugl‐Meyer Assessment, Wolf Motor Function Test Follow‐up: range 16 to 24 weeks	The mean arm function was 0 SD	SMD 0.39 higher (0.17 higher to 0.61 higher)	‐	373 (11 RCTs)	⊕⊕⊝⊝ Lowa,b	Action observation may result in a slight increase in arm function.
Hand function assessed by: Box and Block Test Follow‐up: range 12 to 20 weeks	The mean hand function was 0	MD 2.76 higher (1.04 higher to 4.49 higher)	‐	178 (5 RCTs)	⊕⊕⊝⊝ Low a,b	Action observation may result in a slight increase in hand function.
Dependence on ADL assessed by: Barthel Index, Functional Independence Measure Follow‐up: range 12 to 20 weeks	The mean dependence on activities of daily living was 0	SMD 0.37 higher (0.34 lower to 1.08 higher)	‐	302 (7 RCTs)	⊕⊝⊝⊝ Very lowa,b,c	Action observation may increase/have little to no effect on dependence on activities of daily living but the evidence is very uncertain.
Quality of life assessed by: Stroke Impact Scale Follow‐up: range 8 to 12 weeks	The mean quality of life was 0	SMD 0.13 higher (1.76 lower to 2.02 higher)	‐	30 (2 RCTs)	⊕⊝⊝⊝ Very lowa,b,c	The evidence is very uncertain about the effect of action observation on quality of life.
Cortical activation assessed by: fMRI, MEP, EEG	See comment	See comment	‐	102 (4 RCTs)	‐	Trials could not be pooled due to the variety of measures and the absence of data in some groups.
Motor performance assessed by: Accelerometer, 3‐dimensional motion analysis system, number of acting Follow‐up: mean 1 week	See comment	See comment	‐	91 (4 RCTs)	‐	Trials could not be pooled due to the variety of measures. Experimental groups showed improvements in movement time, peak acceleration and number of repetitions of a task in 1 minute.
Adverse effects	See comment	See comment	‐	16 (2 RCTs)	‐	Trials could not be pooled due to subjectivity of the outcome assessment
*The risk in the intervention group (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). ADL: activities of daily living; CI: confidence interval; EEG: electroencephalography; fMRI: functional magnetic resonance imaging; MD: mean difference; MEP: motor evoked potential;RCTs: randomized controlled trials; SD: standard deviation; SMD: standardized mean difference.
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

^aDowngraded one level due to several ratings with 'unclear' or even 'high' risk of bias in allocation concealment, incomplete outcome data, blinding of outcome assessment or selective reporting.
^bDowngraded one level due to small total population size (< 400).
^cDowngraded one level due to moderate or high heterogeneity (> 50%).