1. Laser versus no treatment outcome details.

Comparison	Outcome	Trials (participants)	Definition of outcome in trial/measurement details	Data reported
585‐nm PDL versus no treatment	Scar severity	2 RCTs (Manuskiatti 2001; 10 participants; 40 segments and Manuskiatti 2002, 10 participants; 20 segments)	Manuskiatti 2001 and Manuskiatti 2002: categories of 25% increments of improvement in scar severity after 32 weeks (graded by the patient)	Number of participants with an improvement of 50% or higher in the scar severity   Manuskiatti 2001: Laser: 23/30 Control: 4/30   Manuskiatti 2002: Laser: 8/10 Control: 4/10
585‐nm PDL versus no treatment	Incidence and severity of treatment‐related adverse effects	3 RCTs (Manuskiatti 2001; 10 participants; 40 segments, Manuskiatti 2002, 10 participants; 20 segments, and Wittenberg 1999; 20 participants; 40 segments)	Manuskiatti 2001: immediate treatment reactions, including purpuric discolorations and erosion secondary to blistering, and adverse sequelae during 32 weeks.   Manuskiatti 2002: immediate treatment reactions included mild to moderate pain during treatment, burning sensation, spots of purpura, erosion secondary to blistering. Treatment‐related adverse sequelae including hypopigmentation, telangiectasia, and skin atrophy during 32 weeks.   Wittenberg 1999: no definition was provided. Duration: 40 weeks.	Manuskiatti 2001 and 2002: in all participants treated with the PDL the area became purpuric and a small number of participants with skin phototype VI reported erosions. Manuskiatti 2002: mild to moderate discomfort or pain related to treatment was in 90% (9/10) of the participants during laser pulsing.   Wittenberg 1999: one (1/20) participant dropped out due to pain during laser treatment.
585‐nm PDL versus no treatment	Scar size, colour, height, length, width, pliability, skin surface texture, pruritus and pain	3 RCTs (Manuskiatti 2001; 10 participants; 30 segments and Manuskiatti 2002: 10 participants; 20 segments; Wittenberg 1999; 20 participants; 40 segments)	Manuskiatti 2001 and 2002: scar height evaluated using a dial calliper, erythema using a hand‐held colorimeter after 32 weeks.   Wittenberg 1999: blood flow (erythema), elasticity and volume, burning, pruritus, and pain not related to treatment after 40 weeks.	Manuskiatti 2001, 2002: scar height improvement in laser treated areas when compared with control (P < 0.05, and P = 0.005, respectively) (data presented only in graphs)   Wittenberg 1999: No statistically significant differences between groups were detected for erythema (P = 0.26), elasticity (P = 0.76), volume (P = 0.13), burning (P = 0.75), pruritus (P = 0.99), and pain not related to treatment (P = 0.41) (results presented only in graphs).
NAFL versus no treatment	Scar severity	2 RCTS (Verhaeghe 2013; 22 participants, 44 segments; Lin 2011; 20 participants; 20 scars)	Verhaeghe 2013: HPGA and PGA using a VAS ranging from 0 to 100 mm (0 = normal skin and 100 = worst possible scar) ‐ smallest clinically important minimum relevant difference was 20 POSAS: containing vascularisation, pigmentation, thickness, relief, pliability, and surface area (observer part) and pain not related to treatment, itching, colour, stiffness, thickness, and relief (patient part) (range 6 to 60) after 3 months.   Lin 2011: categories of 25% increments of improvement in scar severity (graded by the participants and 2 blinded observers) after 3 months.	Verhaeghe 2013 (36 segments analysed): Number of participants who got better according to HPGA and PGA. HPGA: Laser: 10/18 Control: 5/18 PGA: Laser: 10/18 Control: 1/18 POSAS: Patient part (P = .047) Observer part: not significant (details not provided)   Lin 2011: HDTA laser: not significant LDTA: P = 0.001 (data presented only in graphs)
NAFL versus no treatment	Incidence and severity of treatment‐related adverse effects	2 RCTS (Verhaeghe 2013; 22 participants, 44 segments; Lin 2011; 20 participants; 20 scars)	Verhaeghe 2013: treatment‐related adverse effects included erythema, edema, burning sensation, crusts, purpura, vesicles, hyperpigmentation. Duration: 3 months   Lin 2011: side effects, including worsening (erythema, pigmentation, or texture), discolouration, exfoliation, swelling, scabbing, and pain related to treatment, rated on a quartile scale (0 = none, 1 = mild, 2 = moderate, and 3 = severe) during the 3 month‐period.	Verhaege 2013: Percentage of participants reporting treatment‐related adverse effects 4 days after treatment (out of 18 analysed): NAFL treatment: Erythema: 70% Edema: 20% Burning sensation: 18% Crusts: 15% Purpura: 7% purpura Vesicles: 3% After 3 months: Hyperpigmentation: 1 participant *In a small group of participants, the treated part improved less than the untreated part. Median pain (related to treatment) score (IQR) on a VAS (0 = no pain and 100 = worst possible pain) was: Session 1: 37.0 (26.0–53.5) Session 2: 41.0 (26.7–60.7) Session 3: 53.0 (22.5–71.0) Session 4: 48.0 (23.5–78.5)   Lin 2011: Number of participants reporting scar worsening HDTA: 3/10   Higher risk of erythema, exfoliation, and pain related to treatment with HDTA compared with LDTA (P = 0.05, P = 0.02, P = 0.01, respectively) (data on side effects were presented only in graphs).
NAFL versus no treatment	Scar size, colour, height, length, width, pliability, skin surface texture, pruritus and pain	2 RCTS (Verhaeghe 2013; 22 participants, 44 segments; Lin 2011; 20 participants; 20 scars)	Verhaeghe 2013: redness, pigmentation, and skin texture after 3 months   Lin 2011: erythema, pigmentation, texture after 3 months	Verhaeghe 2013: No significant difference in redness, pigmentation, and skin texture (details not provided)   Lin 2011: Mean + SD Erythema: HDTA: 1.33 + 1.26 Control: 0.89 + 0.95 LDTA: 1.06 + 1.26 Control: 0.94 + 1.20 Pigmentation: HDTA: 1.06 + 0.95 Control: 0.94 + 0.82 LDTA: 0.79 + 0.76 Control: 0.71 + 0.76 Texture: HDTA: 2 + 0.76 Control: 1.78 + 0.89 LDTA: 2.19 + 0.95 Control: 1.63 + 0.95
Fractional CO2 Laser versus no treatment	Scar severity	3 RCTS (Azzam 2016: 30 participants; 60 segments, Blome‐Eberwein 2016: 36 participants; 80 scars, Daoud 2019: 23 participants; 46 segments)	Azzam 2016: patient satisfaction, as follows: excellent = more than 75 %, good = 50 to 75%, moderate = 25 to 50 % and poor = less than 25 % improvement after 3 months   Azzam 2016 and Blome‐Eberwein 2016 used the VSS, including pliability, height, colour, and vascularity   Blome‐Eberwein 2016 and Daoud 2019: POSAS including: vascularisation, pigmentation, thickness, relief, pliability, and surface area (observer), itching, colour, and pain not related to treatment stiffness, thickness, and relief (patient) (range 6 to 60) after up to 6 months	Azzam 2016: Number of participants that reported each satisfaction Keloid scar participants Excellent: 6/12 Good: 3/12 Moderate: 3/12 Hypertrophic scar patients Excellent: 2/7 Good: 1/7 Moderate: 2/7 Poor: 2/7   Azzam 2016: VSS (Mean + SD) Keloid scar patients Laser: 5.7 + 2.2 Control: 7.6 + 1.0 Hypertrophic scar patients Laser: 4.6 + 2.5 Control: 7.6 + 2.9   Blome‐Erbewein 2016 VSS (Mean + SD) Hypertrophic scar patients Laser: 6.5 + 2.39 Control: 6.41 + 2.31   Blome‐Eberwein 2016 POSAS Pre‐treatment Laser: 32.64 ± 12.41 Control: 29.91 ± 13.03 Post‐treatment Laser: 28.51 ± 12.85 Control: 24.38 ± 11.41   Daoud 2019 POSAS Significant improvements in all categories except for colour (P < 0.001) (results presented in graphs)
Fractional CO2 Laser versus no treatment	Incidence and severity of treatment‐related adverse effects	1 RCT (Daoud 2019 23 participants; 46 scar segments)	No definition provided	The authors mention that no treatment‐related adverse effects were reported
Fractional CO2 Laser versus no treatment	Scar size, colour, height, length, width, pliability, skin surface texture, pruritus and pain	2 RCTS (Azzam 2016: 30 participants; 60 segments;,Blome‐Eberwein 2016: 36 participants; 80 scars)	Azzam 2016: pruritus and pain not related to treatment after 3 months   Blome‐Eberwein 2016 Scar pliability and height evaluated with suction cup and ultrasound, colour; erythema and pigmentation assessed with Dermaspectrometer), sensation, pruritus, and pain not related to treatment evaluated with POSAS after up to 6 months	Azzam: number of participants complaining of pruritus and pain Pruritus: 16 Pain: 5 (details not provided)   Blome‐Eberwein 2016: pliability, height, recoil Mean and SD – before and after treatment Scar height Pre‐intervention Laser: 3.15 ± 0.37 Control: 2.658 ± 0.344 Post‐treatment: Laser: 2.34 ± 0.313 Control: 2.46 ± 0.342

HDTA: high‐density treatment arm; HPGA: Health Professional Global Assessment; IQR: interquartile range; LDTA: low‐density treatment arm; PGA: patient global assessment; POSAS: Patient and Observer Scar Assessment Scale; (In POSAS, highest values indicate worse scar or sensation); SD: standard deviation; VAS: visual analogue scale; VSS: Vancouver Scar Scale.