Summary of findings 4. Foam surfaces compared with reactive gel surfaces for pressure ulcer prevention.

Foam surfaces compared to reactive gel surfaces for pressure ulcer prevention
Patient or population: pressure ulcer prevention Setting: operating room Intervention: foam surfaces Comparison: reactive gel surfaces
Outcomes	Impact	№ of participants (studies)	Certainty of the evidence (GRADE)
Proportion of participants developing a new pressure ulcer Follow‐up: unspecified	Hoshowsky 1994, involving a totality of 135 individuals (270 halves of bodies), indicated no pressure ulcers developed in either group.	270 (1 RCT)	⊕⊝⊝⊝ Very lowa,b
Time to pressure ulcer development	The included study did not report this outcome.
Support surface associated patient comfort	The included study did not report this outcome.
All reported adverse events	The included study did not report this outcome.
Health‐related quality of life	The included study did not report this outcome.
Cost‐effectiveness	The included study did not report this outcome.
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 twice for high risk of bias in domains other than performance bias.
^bDowngraded twice for imprecision due to the small sample size and the low event rate.