Lin 2011.

Study characteristics
Methods	Study design: prospective randomised intra‐individual (split‐scar) controlled trial with 2 treatment arms conducted in the USA. Scar segment as the unit of randomisation. Duration of the study: recruiting between October 2008 and March 2009, plus 4.5 months of study duration Follow‐up time: 4.5 months (intermediate‐term follow‐up) Protocol was published before recruitment of participants: participants were recruited according to a protocol approved by the Massachusetts General Hospital's institutional review board Details of trial registration: not reported Funding sources: none declared
Participants	Number of participants assigned: 20 participants with (with a total of 20 scars treated ‐ 1 scar per participant) Group A (NAFL‐ Non‐ablative fractional laser / High‐Density Treatment Arm ‐ HDTA): 10 participants (total of 20 segments enrolled) Segment 1A: a total of 10 segments treated Segment 2A: a total of 10 segments not treated (control) Group B (NAFL ‐ Non‐ablative fractional laser / Low‐Density Treatment Arm ‐ LDTA): 10 participants (total of 20 segments enrolled) Segment 1B: a total of 10 segments treated Segment 2B: a total of 10 segments not treated (control) Loss: 3 participants. Number of participants assessed: 17 individuals Group A: 9 individuals (total of 18 segments) Group B: 8 individuals (total of 16 segments) Inclusion criteria: presence of post‐surgical hypertrophic scars of at least 6 months duration; scars were required to be at least 2 cm long. Exclusion criteria: scars that had received previous treatment, or were present on the face, hands, and feet; people with a history of keloids or isotretinoin use within the last 6 months prior to laser treatment. Age: (group A) 42; 28 to 67 years (mean; range); (group B) 40; 23 to 66 (mean; range) Gender: female: 18; 90 (number; %); male: 2; 10 (number; %). Duration of scars: (group A) 8.3 years; 0.5 to 29 years (mean; range); (group B) 7.3 years; 1.5 to 23 years (mean; range). Skin phototypes: (group A) I‐VI; (group B) II‐VI Scar Location: (group A) neck, chest, back, abdomen, arm, sacrum; (group B) neck, chest, arm, abdomen, shoulder, suprapubic Scar Length: (group A) 9.58 cm; 1‐23.5 cm (mean; range); (group B) 6.94 cm; 2.2‐17 cm (mean; range)
Interventions	Group A (NAFL ‐ HDTA): Segment 1A: half of the hypertrophic scar was treated with a Non‐Ablative Fractional Laser (NAFL) at 1550 nm wavelength (40 mJ and per cent coverage of 26%) Segment 2A: half of the scar was not treated, serving as an internal control Group B (NAFL ‐ LDTA): Segment 1B: half of the hypertrophic scar was treated with a Non‐Ablative Fractional Laser (NAFL) at 1550 nm wavelength (40 mJ and per cent coverage of 14%) Segment 2B: half of the scar was not treated, serving as an internal control Obs: in both 1A and 1B groups, the equipment used was the Fraxel Re:Store laser (Solta Medical, Hayward, CA). For each treatment, 8 passes were used. Each participant received a treatment every 2 weeks (in 1 half of the scar) for a total of 4 treatments. The follow‐up was done at 1 month and 3 months after the last treatment.
Outcomes	Primary outcomes Overall Appearance (by Blinded Observers): Two blinded dermatologists analysed scar severity improvement according to overall appearance, assessing standardised photographs taken prior to every treatment and at the 1‐month and 3‐month follow‐up visits. They rated both the control side and the treatment side at 1 month and 3 months, using a quartile scale (0 = no improvement or worsened, 1 = minor improvement, 2 = moderate improvement, and 3 = marked improvement). Overall Appearance (by Patient Self‐assessment): At the end of the study participants evaluated the improvement of treated sides of the scar using a 4‐point scale (1 = 0 to 25% improvement, 2 = 25% to 50% improvement, 3 = 50% to 75% improvement, and 4 = 75% or greater improvement). Treatment‐related adverse effects: Side effects, including erythema, discolouration, exfoliation, pain, swelling, and scabbing, were rated on a quartile scale (0 = none, 1 = mild, 2 = moderate, and 3 = severe). Results were presented only in a figure, for both treatment sides (HDTA and LDTA). Secondary Outcomes: Changes in Pigmentation, Erythema and Texture: 2 blinded dermatologists rated independently both the control side and the treatment side at 1 month and 3 months, using a quartile scale (0 = no improvement or worsened, 1 = minor improvement, 2 = moderate improvement, and 3 = marked improvement). Volume Measurement: obtained by a blinded observer using optical frequency domain imaging (OFDI), a 2nd generation of optical coherence tomography to measure the change in scar depth within the scar mould. Measurements were made prior to treatment, and at the 1‐month and 3‐month follow‐up visits. Two representative scars from each arm were calculated.
Notes	One participant from HDTA did not complete the study due to perceived worsening of the scar. Two participants from LDTA did not complete the study: 1 moved away before the 3‐month follow‐up, and 1 had to stop the treatments due to an unrelated emergent illness. The article was presented as an abstract at the 2009 ASLMS annual meeting under the support of a USAF travel grant.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Each scar was divided in half and a treatment side was randomly assigned using a coin flip.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	This was a single‐blinded trial. Participants and health professionals performing the treatment were not blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Observers were blinded and rated each half of the scar (control and treatment) independently.
Incomplete outcome data (attrition bias) All outcomes	High risk	Three participants dropped out of the study. The reasons were described by the author. One of them gave up because of scar worsening. As‐treated analyses were performed.
Selective reporting (reporting bias)	Low risk	No trial protocol is available, but all parameters listed in the methods section to assess changes in the scars were described.
Other bias	Low risk	No other sources of bias were found.