Summary of findings 1. Prehabilitation compared to no prehabilitation in adult patients undergoing surgery for colorectal cancer.

Prehabilitation compared to no prehabilitation in adult patients undergoing surgery for colorectal cancer
Patient or population: adult patients undergoing surgery for colorectal cancer Setting: in‐hospital, outpatient or home‐based interventions Intervention: multimodal prehabilitation Comparison: no prehabilitation
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with no prehabilitation	Risk with multimodal prehabilitation
Functional capacity 4 weeks postoperatively assessed with: 6MWT in metres	The mean functional capacity four weeks postoperatively ranged from 286.1 to 444 metres	MD 26.02 meters higher (13.81 lower to 65.85 higher)	Not estimable	131 (2 RCTs)	⊕⊕⊝⊝ LOW 1 2
Functional capacity 8 weeks postoperatively assessed with: 6MWT in metres	The mean functional capacity eight weeks postoperatively ranged from ‐21.8 to 11 metres	MD 26.58 metres higher (8.88 lower to 62.04 higher)	Not estimable	140 (2 RCTs)	⊕⊝⊝⊝ VERY LOW 1 2 3	The values reported in the 'Risk with no prehabilitation' column are mean changes from baseline.
Complications within 30 days postoperatively	417 per 1.000	396 per 1.000 (292 to 538)	RR 0.95 (0.70 to 1.29)	250 (3 RCTs)	⊕⊕⊝⊝ LOW 1 2
Health‐related quality of life	See comment	See comment	Not estimable	182 (2 RCTs)	See comment	SF‐36 and HADS results were reported in two studies (Gillis 2014, Carli 2020). We were not able to pool data. Both trials did not report between‐group differences.
Functional capacity pre‐surgery assessed with: 6MWT in metres	The mean functional capacity pre‐surgery ranged from ‐16.4 to 315.8 metres	MD 24.91 metres higher (11.24 higher to 38.57 higher)	Not estimable	225 (3 RCTs)	⊕⊕⊕⊝ MODERATE 1	Both post‐intervention scores and mean change from baseline are displayed in the "Risk with no prehabilitation" column.
Length of hospital stay	See comment	See comment	Not estimable	250 (3 RCTs)	See comment	Meta‐analysis could not be performed. The three studies (Gillis 2014, Bousquet‐Dion 2018, Carli 2020) found that results were similar between groups.
Mortality	See comment	See comment	Not estimable	‐	See comment	Not reported in either study
Safety of the programme (dropout, SAE)	See comment	See comment	Not estimable	‐	See comment	Meta‐analysis could not be performed. Information was insufficient to draw conclusions.
*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). 6‐MWT: 6‐minute walk test; CI: Confidence interval; kg: Kilogram; MD: Mean difference; ml: Millilitre; OR: Odds ratio; RCT: randomised controlled trial; RR: Risk ratio; SAE: Serious adverse event; VO2peak: Peak oxygen uptake.
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

¹ Downgraded for risk of bias. Participants and personnel were not blinded (due to the nature of the programme), outcome assessors were blinded. 

² Downgraded for imprecision. Information size was not reached and the confidence intervals encompass both considerable benefit and considerable harm. 

³ Downgraded for inconsistency. Results were inconsistent between studies and heterogeneity is substantial with an I² of 65%.