Table 2.
Comparison of interventions for acne scars (continued).a
| 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.