Johnston 2012.

Methods	Randomized cross‐over trial
Participants	18 preterm infants (PMA 28 to 36 completed weeks) Postnatal age, range, days: within 10 days Birth weight, mean, grams: 2200 Painful procedure: heel lance Study period: October 2007 to January 2010
Interventions	Intervention: 30 minutes of skin‐to‐skin care before and during heel stick provided by the mother Comparison: 30 minutes of skin‐to‐skin care before and during heel lance provided by an unrelated woman Provider: mother or an unrelated woman
Outcomes	PIPP score at 30, 60, 90, and 120 minutes
Notes	Country: Canada Power calculation: no
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Sequence generation not described in text. Author communication confirmed that an off‐site computer‐generated randomization and sequentially numbered allocation program was used
Allocation concealment (selection bias)	Low risk	Allocation concealment not described. Author communication confirmed that an off‐site computer‐generated randomization and sequentially numbered allocation program was used
Blinding (performance bias and detection bias) All outcomes	Unclear risk	"Close‐up video recordings of the infants' faces were made using a KS162 digital camera...or a webcam." Not clear if mothers' skin/breasts could be noted by researchers
Incomplete outcome data (attrition bias) All outcomes	Low risk	"...of the 82 infants meeting the selection criteria, 21 initially refused at the time of asking, and another refused after condition order had been randomized. The main reason for refusal was not wanting another woman to provide kangaroo care with her baby." Drop out rates clearly explained in Figure 2 and incomplete data accounted for
Selective reporting (reporting bias)	Low risk	Outcomes were clearly laid out in Figure 2
Other bias	Unclear risk	"All data were coded and analyzed in the research laboratory at the off‐site university. Faces were coded second‐to‐ second on a stop frame system. Coders were trained on faces from similar studies, and inter‐rater reliability was over 90%. Coders were from outside the unit and did not know the purpose of the study, because the camera was focused on the infant’s face. Intrarater reliability was checked every 3 months and was maintained over 90%." Washout period not described