Wittenberg 1999.

Methods	RCT
Participants	Teaching Hospital, USA 20 patients Inclusion criteria: adults with uniform, linear hypertrophic scars secondary to surgical wounds Exclusion criteria: treatment of the scar within the preceding 2 months, keloidal scarring, scars less than 8 cm long Sex: 5 male, 15 female Age: 24 to 81
Interventions	Each scar was divided into 3 sections, and each section was randomly assigned to 1 of 2 treatments (585 nm pulsed laser or silicone gel sheet) or designated as a control
Outcomes	Length of follow‐up: measurements at 0, 8, 16, 24 and 40 weeks Clinical: hypertrophic scar blood flow, elasticity and volume Histological assessment of fibrosis, number of telangiectasias, number of mast cells Patient' subjective complaints of pruritis, pain and burning Consenting patients (n = 5) underwent punch biopsies at 0 and 40 weeks Complications: 1 patient unable to use silicone gel sheet due to skin irritation, 1 patient withdrew because of pain during laser treatment
Notes	Elasticity measured by elastometer Blood flow measured with a laser Doppler Patients rated pain and burning on a quartile scale (1 = no/minimal pain, 4 = severe)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Each scar was divided into three sections and each section was either randomly assigned to 1 of 2 treatments (SGS or FLPDL) or designated as control using a computer‐generated randomization list”. Comment: we judged randomisation to be adequate
Allocation concealment (selection bias)	Unclear risk	Comment: no information is given on allocation concealment which we judged to be at unclear risk of bias
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: “Patients were instructed to wear silicone gel sheeting on the designated site for at least 12 continuous hours per day . . . one section of the patients scar underwent flash lamp‐pumped pulsed‐dye laser . . . one section was randomised to control and left untreated for the study duration”. Comment: due to the nature of the treatment, we judged that participants and personnel could not be blinded
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: no information was given regarding outcome assessment which we judged to be at unclear risk of bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: “20 [patients] were enrolled in the study. Patient 10 did not use SGS due to skin irritation. Patient 6 dropped out of the study at week 24 because of pain during laser treatment". Comment: loss to follow‐up was less than 20% and we therefore judged it to be at low risk of bias
Selective reporting (reporting bias)	Low risk	Comment: the study protocol was not sought, however all measurements discussed in the methods are reported in the results and clinically meaningful outcomes presented.
Other bias	High risk	Quote: “We thank Smith and Nephew for supplying silicone gel sheeting” Comment: Smith & Nephew was the brand of silicone gel used in the trial. We judged this to cause a high risk of bias.

CCT: controlled clinical trial; ITT: intention‐to‐treat; RCT: randomised controlled trial; SD: standard deviation