Research Letter
doi:10.2196/37060
Keywords
Acne vulgaris is a common skin condition that affects both adolescents and adults worldwide and frequently results in acne scars []. Atrophic scars are the most common type of acne scars and are caused by a loss of collagen that leads to depressions in the skin surface []. Currently, many options exist for acne scar treatment, including lasers, chemical peels, dermabrasion, injectable fillers, needling, subcision, punch excision, and punch elevation. However, providers and patients have few guidelines on how to optimize treatment. Because of the large disease burden and the physical, psychological, and social impact of acne scarring, it is important to provide guidelines for patients and providers on the safest and most effective treatments for this complication.
A 2016 Cochrane study [] provided a comprehensive review of available treatments and their efficacy for treating facial atrophic acne scars. This review analyzed 24 randomized controlled trials (RCTs) and assessed two primary outcomes: participant-reported scar improvement and serious adverse events that caused withdrawal from the study. Secondary outcomes such as investigator-assessed scar improvement, patient satisfaction, quality of life, participant-reported or investigator-assessed short-term adverse events, and duration of postprocedure downtime were also measured.
Data from some of the included RCTs showed that fractional laser, chemical peeling (with and without skin needling), and injectable fillers were more effective than comparator treatments. Many studies that compared other treatment modalities to each other or to placebo concluded no significant difference in either participant-reported or investigator-assessed scar improvement. and summarize the treatment comparisons of the 24 included RCTs.
This review [] found moderate support for the use of injectable fillers in acne scar treatment and limited support for lasers, chemical peeling, radiofrequency, and skin needling. The authors could not recommend one treatment modality over another due to insufficient evidence supporting any particular treatment. The included studies were generally underpowered and had a high risk for bias due to lack of blinding and participants’ expectations of treatment influencing improvement ratings. Assessment of acne scar treatment efficacy poses challenges secondary to differences in study parameters across studies, variable subjective improvement rating scales, and lack of long-term follow-up of scar improvement. Additional RCTs with larger study populations, sham and/or placebo trials, and standardized outcomes and improvement ratings are necessary to determine the efficacy of treatment [].
Results of clinical trials published subsequent to this review [] provide further insight. A double-blind, parallel, multicenter RCT [] compared the effects of polymethylmethacrylate (PMMA) microspheres in collagen (ArteFill) injections to placebo (saline injections) as a treatment for acne scarring and reported treatment success in 64% of treated participants vs 33% of control participants after 6 months (P=.0005). Another multicenter, randomized, prospective study [] compared combination microneedling with PMMA-collagen gel filler injections vs microneedling alone, and found the combination group had significantly improved acne scar scores at 24 weeks post treatment compared to the microneedling-alone group (P=.0136). These studies further support the efficacy of injectable fillers for treating acne scars, though additional research with long-term follow-up is warranted to assess the durability of outcomes.
| Comparisona | Study details | Scar improvement | Adverse events | Quality of evidence | Risk of bias |
| Nonfractional nonablative (NFNA) laser vs placebo/no treatment | Frequency-doubled 532-nm Nd:YAG (neodymium:yttrium-aluminium-garnet) laser; within-individual study | Participant reported (PR): 53.6% improvement in acne scarring (range: 10%-90%); no data for untreated | None reported | Not assessed | High risk of detection bias |
| Fractional laser (FL) vs NFNA laser | CO2 FL vs Q-Switched 1064-nm Nd:YAG laser; parallel-group study | PR: 12/32 (FL) vs 3/32 (NFNA laser) participants reported >50% improvement in scars at 6 months (risk ratio [RR] 4.00, 95% CI 1.25-12.84) | Transient posttreatment burning sensation in the NFNA group; postinflammatory hyperpigmentation (PIH) reported in 16/64 subjects | Very low-quality evidence | Unclear risk of detection bias |
| FL vs placebo/no treatment | 1540-nm Er:Glass FL; within-individual study | PR: 8/10 patients reported improved acne scars after 12 weeks; no data for untreated | Immediate pain and transient erythema post treatment | Not assessed | High risk of detection bias |
| FL vs placebo/no treatment | CO2 FL; within-individual study | PR: 12/12 subjects reported mild to moderate improvement in scars after 6 months; no data for untreated side | Mild to moderate pain, erythema, and wound formation | Not assessed | High risk of detection bias |
| FL vs radiofrequency (RF) | 1550-nm Er:Glass FL vs fractional RF; parallel-group study | PR: 7/20 (FL) vs 9/20 (RF) participants reported >50% improvement in acne scarring at <24 weeks post treatment (RR 0.78, 95% CI 0.36-1.68) | Pain with FL greater than with RF; both groups reported erythema and edema; PIH in the FL group only | Very low-quality evidence | High risk of detection bias |
| FL vs RF | 1550-nm Er:Glass laser vs fractional bipolar RF; within-individual | PR: mean improvement grade in acne scars after treatment; fractional laser (2.89, SD 0.57) vs RF (2.74, SD 0.73) | 1/20 participants withdrew due to prolonged dyspigmentation negatively affecting quality of life | Not assessed | Unclear risk of detection bias |
| FL vs RF | 10,600-nm CO2 FL vs fractional microplasma RF; within-individual | Investigator assessed (IA)c: acne scar improvement in FL (59.2%) vs RF (56.4%) (P=.93) | Posttherapy erythema, scaling, and PIH were more significant on the FL side | Not assessed | Not assessed |
| FL vs combined FL with any active intervention | 10,600-nm CO2 FL alone vs same laser plus punch elevation; within-individual | IAc: 26/42 (FL) vs 31/42 (FL with punch elevation) investigators reported >50% acne scar improvement at <24 weeks (RR 1.45; P=.02) | Transient erythema, crusting, transitory burning after treatment, and mild PIH occurred with both interventions | Not assessed | Not assessed |
| FL vs combined FL with any active intervention | CO2 FL with saline vs CO2 FL with autologous platelet-rich plasma (PRP); within-individual | IAc: mean degree of clinical improvement for FL (2.3, SD 0.5) vs FL with PRP (2.7, SD 0.7) | Posttreatment crusting and edema lasted significantly longer on the FL-alone side than on the combined treatment side | Not assessed | Not assessed |
| FL vs chemical peeling (CP) | 1550-nm Er:Glass FL vs chemical reconstruction of skin scars CP method; within-individual | IAc: average improvement grades after <24 weeks: FL (2.51) vs CP (2.44) | 1/20 participants left the trial due to minor discomfort with treatment from pain and redness | Not assessed | Not assessed |
| FL vs combined CP with needling | Nonablative 1540-nm Er:Glass FL vs CP with trichloroacetic acid (TCA) 20% with skin needling; parallel-group | PR: 9/13 (FL) vs 9/13 (combined CP with needling) participants reported >50% acne scar improvement after 12 months (RR 1.00, 95% CI 0.60-1.67) | Pain, transient edema, and erythema were reported in both groups | Very low-quality evidence | High risk of detection bias |
| CP vs placebo/no treatment | Glycolic acid peels (at different concentrations) vs 15% glycolic acid cream vs placebo cream; parallel-group studyd | IAc: significantly better response in the CP group vs placebo (P<.05) | CP group: 7 participants withdrew (intolerance to high concentrations, longer contact times of peeling agent); RR 5.45, 95% CI 0.33-90.14 | Very low-quality evidence | High risk of attrition bias |
aStudies did not stratify patients based on acne severity (mild, moderate, severe), which may affect response to scar treatment.
bItalicized studies indicate statistically significant study results.
cPatient-reported scar improvement was not assessed in this study; investigator-reported scar improvement results were included.
dBoth treatment arms (glycolic acid peels and glycolic acid creams) were combined into 1 treatment comparison group for analysis.
| Comparisona | Study details | Scar improvement | Adverse events | Quality of evidence | Risk of bias |
| Chemical peeling (CP) vs combined CP plus any active intervention | Deep peeling with oil phenol in a 60% concentration formula nonhydroalcoholic solution vs trichloroacetic acid (TCA) 20% with skin needling; parallel-group study | Participant reported (PR): 10/10 (CP) vs 8/10 (CP with needling) participants reported >50% acne scar improvement after 8 months (RR 1.24, 95% CI 0.87-1.75) | All participants reported pain and transient erythema in both groups | Very low-quality evidence | High risk of detection bias |
| CP vs needling | 100% TCA chemical reconstruction of skin scars (CROSS) vs skin needling using dermaroller; parallel-group study | PR: 9/12 (TCA CROSS) vs 10/15 (skin needling) participants reported >50% acne scar improvement at 1 month (RR 1.13, 95% CI 0.69-1.83) | All participants reported pain and transient erythema in both groups; 6/12 participants in the peeling group experienced postinflammatory hyperpigmentation (PIH) | Very low-quality evidence | High risk of detection and attrition bias |
| Needling vs placebo/no treatment | Needling vs topical anesthetic cream; within-individual study | PR: 41% mean improvement in acne scars on the treated side | All participants reported pain, and transient erythema and edema were seen in all participants | Not assessed | Not assessed |
| Injectable fillers vs placebo/no treatment | Polymethylmethacrylate suspended in bovine collagen vs saline injections; parallel-group study | PR: 77% (injectable filler) vs 42% (placebo) of participants reported improved acne scarring (RR 1.84, 95% CI 1.31-2.59; P<.05) | Injection site pain, injection site tenderness, swelling, erythema, bruising, pain, itching, lumps or bumps, and discoloration | Moderate-quality evidence | Low risk of detection bias |
| Injectable fillers vs placebo/no treatment | Autologous fibroblasts vs vehicle control; within-individual study | PR: 43% of treated sides showed ≥2-point acne scar improvement compared with 18% of the vehicle-control treated side (P<.001) | Participants in both groups reported mild to moderate erythema | Not assessed | Low risk of detection bias |
| Injectable fillers vs subcision | Injectable filler with natural-source porcine collagen vs 18-gauge Nokor subcision needle; within-individual study | PR: 3.5 (injectable filler) vs 3.9 (subcision) global improvement rate (P=.12) | Higher severity of bruising reported with subcision vs fillers | Not assessed | High risk of detection bias |
| Microdermabrasion (MDA) + aminolevulinic acid (ALA)–photodynamic therapy (PDT) vs MDA + placebo-PDT | 417-nm blue light therapy plus MDA with 20% δ-ALA or vehicle solution | Investigator assessed (IA)c: 80% of participants showed acne scar improvement on the MDA + ALA-PDT side vs the MDA + vehicle-PDT side | None reported | Not assessed | Not assessed |
| Fractional laser (FL) vs FL | Er:YAG FL vs CO2 FL laser; within-individual | PR: 70% (Er:YAG) vs 60% (CO2) of laser sites were rated as showing >50% improvement in acne scarring (P=.47) | Participants reported erythema, edema, superficial crusting, and PIH | Not assessed | Not assessed |
| Photothermolysis vs FL | Nonablative 1550-nm erbium-doped fractional photothermolysis system (FPS) vs 10,600-nm CO2 FL system; within-individual | IAc: mean grade of improvement for FPS (2.0, SD 0.5) vs FS (2.5, SD 0.8) (P=.158) | Mean pain scores were significantly lower for FPS than with FL; side effects included crusting, scaling, redness, fluid retention, and hyperpigmentation | Not assessed | Not assessed |
| Pulsed dye laser (PDL) vs long-pulsed laser | Nonfractional nonablative (NFNA) PDL vs 1064-nm long-pulsed Nd:YAG (neodymium:yttrium-aluminium-garnet) laser; within-individual | IAc: acne scores improved by 18.3% (PDL) and 18.7% (Nd:YAG); no statistically significant difference between treatments | Reported adverse events included transient pain, erythema, and edema in treated areas | Not assessed | Not assessed |
| Long-pulsed Nd-YAG laser vs diode laser | NFNA 1320-nm long-pulsed Nd-YAG laser vs NFNA 1450-nm diode laser; within-individual | IAc: higher average clinical scores on 1450-nm diode laser–treated face side than on Nd-YAG laser–treated face side | All participants experienced posttreatment erythema, and some had PIH and discomfort with treatment | Not assessed | Not assessed |
| Long-pulsed Nd-YAG laser vs combined laser | Long-pulsed Nd:YAG laser vs combined 585/1064-nm laser; within-individual | IAc: acne scores improved by 27% (Nd:YAG) and 32.3% (585/1064-nm laser); no statistically significant difference | Reported adverse events included transient pain, erythema, and edema in both treated areas | Not assessed | Not assessed |
aStudies did not stratify patients based on acne severity (mild, moderate, severe), which may affect response to scar treatment.
bItalicized studies indicate statistically significant study results.
cPatient-reported scar improvement was not assessed in this study; investigator-reported scar improvement results were included.
Editorial Notice
The views expressed in this paper are those of the authors and in no way represent the Cochrane Library or Wiley.
This article is based on a Cochrane Review previously published in the Cochrane Database of Systematic Reviews 2016, Issue 4, DOI: 10.1002/14651858.CD011946.pub2 (see www.cochranelibrary.com for information). Cochrane Reviews are regularly updated as new evidence emerges and in response to feedback, and Cochrane Database of Systematic Reviews should be consulted for the most recent version of the review.
Conflicts of Interest
RPD is a joint coordinating editor for Cochrane Skin, editor-in-chief of JMIR Dermatology, a dermatology section editor for UpToDate, a social media editor for the Journal of the American Academy of Dermatology, and a podcast editor for the Journal of Investigative Dermatology (JID). He is a coordinating editor representative on Cochrane Council. TES serves as an editorial board member-at-large for JMIR Dermatology. ALC and RAH declare no conflicts of interest.
RPD receives editorial stipends (JMIR Dermatology, JID), royalties (UpToDate), and expense reimbursement from Cochrane Skin. TES receives fellowship funding from Pfizer and the National Institutes of Health.
References
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- Biesman BS, Cohen JL, DiBernardo BE, Emer JJ, Geronemus RG, Gold MH, et al. Treatment of atrophic facial acne scars with microneedling followed by polymethylmethacrylate-collagen gel dermal filler. Dermatol Surg 2019 Dec;45(12):1570-1579. [CrossRef] [Medline]
Abbreviations
| PMMA: polymethylmethacrylate |
| RCT: randomized controlled trial |
Edited by R Alhusayen; submitted 05.02.22; peer-reviewed by B Peethambaran, J Solomon, K Ashack; comments to author 17.07.22; revised version received 24.07.22; accepted 02.08.22; published 17.08.22
Copyright©Annie L Cao, Torunn E Sivesind, Rania Abdel Hay, Robert P Dellavalle. Originally published in JMIR Dermatology (http://derma.jmir.org), 17.08.2022.
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