To evaluate the efficacy and safety of laser interventions for facial acne scars: a systematic review and Bayesian network meta-analysis
Highlight box
Key findings
• This study has identified a meaningful therapeutic approach for acne scars.
What is known and what is new?
• A large number of existing randomized controlled experiments have compared 2–3 acne scar treatments, or a single method for meta-analysis.
• To date, there has been no research on the use of network meta-analysis to compare all laser treatments. This study evaluates the efficacy and safety of laser interventions in the treatment of acne scars, which is an innovative point.
What is the implication, and what should change now?
• This research is more comprehensive, involving more types of lasers, and the results are more instructive. In the future, based on the results of this trial, we should conduct further clinical trials of the most effective treatment to prove the significance of this treatment for acne scars.
Introduction
Acne vulgaris, a chronic inflammatory disorder confined to pilosebaceous units, is characterized by pimples, papules, pustules, and nodules, and is often complicated with scars (1). The onset of acne usually occurs in puberty, affecting approximately 27% of adolescents and 93% of late teens. The face, neck, chest, and upper back are the regions typically affected by acne vulgaris (2). The etiology is complicated, including increased sebum secretion induced by androgens, inflammatory keratinization, colonization of Cutibacterium acnes in the pilosebaceous unit, delayed immune response, diet, and genetic factors (3). Different skin lesions may occur at different stages of the formation and remission of acne vulgaris. Acne scarring is now a common disease leading to impaired facial appearance and significant negative effects on patients’ mental health and daily life (4). Among the population aged 11–30 years, 80% may experience acne at some point, with subsequent scarring affecting about 40% (5). Among the types of scars, the depressed acne scar is relatively serious, which manifests the likeness of an orange peel, ice pick, meteorite crater, and so on (6). Acne scarring is associated with people’s satisfaction with their appearance, low self-esteem, and inferiority complex, which can result in anxiety, depression, and even suicidal thoughts (7).
With the increasing demand for beauty, the healing of acne scars is the focus and challenge of acne treatment. Currently, acne scars are treated with grinding, surgical release, plasma therapy, autologous fibroblasts, platelet-rich-plasma (PRP), and laser therapy, among others. Different treatments for acne scars have different effects and complications (8). At present, laser treatment is the most common method for treating acne scars. The principle of laser treatment is photothermy. Relevant studies have demonstrated that different laser parameters and techniques might have different efficacy on different forms of acne scars (9). The commonly used laser treatments include the 1,064 nm long pulsed neodymium: yttrium-aluminum-garnet (Nd:YAG) laser (1064Nd), 1,550 nm Erbium: glass fractional laser (1550Er), fractional CO2 laser (FCL), 2,940 nm erbium fractional laser (2940FEL), picosecond 755 nm alexandrite laser (755PAL), pulsed dye laser (PDL), and so on. Currently, there are various types of laser treatments for acne scars, but the pros and cons of different laser intervention methods in scar treatment still remain controversial.
The main role of network analysis is to comprehensively evaluate and rank all the interventions in the same body of evidence simultaneously. It can combine both direct and indirect comparisons, which cannot be accomplished by conventional meta-analysis. Therefore, this Bayesian network analysis was conducted to investigate the effect of diversified laser treatment methods on acne scar with the aim of providing a reference for clinical practice. Through searching, we found that there were conflicting results between some studies on the treatment of acne scars. Up to now, there is still a lack of network meta-analysis basis for the selection of laser. Therefore, we carried out this research analysis to explore the optimal method for acne scars. We present the following article in accordance with the PRISMA-NMA reporting checklist (available at https://atm.amegroups.com/article/view/10.21037/atm-22-5997/rc).
Methods
This systematic review was registered on PROSPERO (ID: CRD42022361585).
Retrieval strategy
Based on the Cochrane Collaboration criteria, the databases of PubMed, Web of Science, Embase, and Cochrane were searched for publicly published randomized controlled trials (RCTs) on laser treatment or combined therapy of laser treatment and other non-laser treatment for acne scars. We also screened relevant meta-analyses published previously. Subject terms and free words were used in the retrieval process, and there was no restriction on region or language. The subject terms mainly included acne, acne vulgaris, and laser, or their synonyms. The detailed retrieval strategy is presented in Table S1.
Inclusion and exclusion criteria
The inclusion criteria were as follows:
- Population: Patients diagnosed with pathological acne scarring.
- Intervention: Treatment including laser (monotherapy or combined therapy).
- Comparison: Different types of lasers, medication, or other non-laser therapeutic strategies.
- Outcome: ECCA score (échelle d’évaluation clinique des cicatrices d’acné), GBS score (Goodman & Baron quantitative global scarring grading system), cure rate (blinded dermatologists using a quartile grading scale for assessment of clinical improvement of skin smoothness: Grade 1: 0–25% = poor improvement, Grade 2: 26–50% = fair improvement, Grade 3: 51–75% = good improvement, and Grade 4: >75% = excellent improvement), satisfaction (on the last visit, the patients were asked to rate the appearance of the scar, skin texture, and overall satisfaction compared with these factors before treatment on a scale of 1: not satisfied, 2: slightly satisfied, 3: satisfied, and 4: very satisfied).
- Study design: The included original studies were RCTs.
The exclusion criteria were as follows:
- Population: Patients with non-pathological acne scars.
- Intervention: Studies that did not include laser treatments, or the studies used different treatment frequencies/cycles of the same type of laser.
- Comparison: There was a lack of control groups in the study.
- Outcome: In the original study, there was a lack of outcome measures evaluating scar improvement, such as cost analyses.
- Study design: The included original studies were non-RCTs (e.g., retrospective studies, single-arm studies, reviews, etc.).
Interventions
In the included studies, the intervention group mainly used laser therapy, and other therapies combined with non-laser treatment were considered as independent interventions in our meta-analysis to reduce the bias caused by other non-laser therapies.
Literature screening and data extraction
The retrieved literature was imported into Endnote (Clarivate, London, UK). After excluding the duplicated publications, the original studies were screened by titles or abstracts to obtain initially eligible studies. The eligible studies finally included in this research were selected based on the full text. Before data extraction, a standard data extraction spreadsheet was made and the content included title, author, year, comparison, intervention, sample size, intervention protocol, acne scar evaluation form (ECCA and GBS), patients’ satisfaction, response rate, complications, and so on.
The aforementioned literature screening and data extraction were conducted independently by 2 researchers (ZXZ and QL) and cross-checked after completion. If there was any dissent, a third investigator (WHC) was consulted to make a decision.
Quality assessment
Two independent researchers evaluated the risk of bias in the included studies using the Cochrane Collaboration Risk of Bias Tool. Upon the completion of the quality assessment, they cross-checked their results. Any disagreements were solved by a third researcher. The risk of bias assessment by the Cochrane tool involved 7 items in 6 domains: (I) selection bias (random sequence generation, Allocation concealment); (II) performance bias (blinding of participants and personnel); (III) detection bias (Blinding of outcome assessment); (IV) attrition bias (incomplete outcome data); (V) reporting bias (selective reporting); (VI) other bias. Each item was answered as “high risk of bias”, “low risk of bias”, or “unclear”.
Statistical analysis
Network meta-analysis uses the Bayesian random-effects model to compare the effectiveness of various interventions. The Markov chain Monte Carlo method was used for modeling, with four Markov chains running at the same time and the number of annealing set to 20,000. After 50,000 simulation iterations, a model was constructed. The Deviation Information Criterion (DIC) was used to analyze the model fitting and global variable consensus. If there were closed loops, we would use the node-splitting method to analyze the local consensus. Furthermore, interventions were sorted based on surface under the cumulative ranking curve (SUCRA), and a league table was generated to present the difference in the effectiveness between interventions (Table S2). A funnel plot was used to directly reflect the heterogeneity among the studies. Stata 15.0 (Stata Corporation, College Station, TX, USA) was used for data analysis. A P<0.05 indicates statistical significance.
Results
Literature search
After the literature search by subject terms and free words, 120 articles were found in PubMed, 528 in Embase, 368 in Cochrane, and 491 in Web of Science. After excluding 523 duplicated publications, 984 articles remained. Afterwards, 155 articles were screened by reading of titles and abstracts. Articles were excluded if the full text was not available or the research subjects did not meet the inclusion criteria. A total of 72 articles were finally included (Figure 1).
The basic characteristics of the included studies
After downloading the full text for screening, a table of basic characteristics was created to extract the basic characteristics of the included studies (Table 1). Among the 72 included articles, 18 were from Egypt, 13 from China, 11 from Korea, 8 from Thailand, 5 from the USA, 6 from India, 2 from Iraq, 1 from Indonesia, 1 from the UK, 2 from Turkey, 1 from Belgium, 1 from Brazil and 3 from Iran. The sample size was between 5 and 350 cases, and the publication time was from 2004 to 2022.
Table 1
No. | Author | Year | Study design | Country | Intervention | Number of cases [faces] | Total number of samples [faces] | Gender (male/female) | Age, years | Course of the disease | Course of treatment | Follow-up time | Outcome indicator |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Zhang YJ (6) | 2022 | Randomized, split-face study | China | 30% supramolecular salicylic acid + ultra-pulsed CO2 fractional laser; ultra-pulsed CO2 fractional laser | 20; 20 | 20 [40] | – | – | – | – | 3 months | ECCA |
2 | Wang Y (10) | 2022 | Randomized | China | Fractional CO2 laser; fractional CO2 laser + PRP + Yifu | 350; 350 | 700 | 66 M 84 F; 64 M 86 F | 15–31; 16–32 | 1–2 years | – | – | Clinical effect, ECCA, DLQI, VSS |
3 | Sabry HH (11) | 2022 | Split-face comparative double-blinded | Egypt | Long-pulsed Laser Nd:YAG 1,064 nm; fractional CO2 laser | 20; 20 | 20 [40] | – | At least 18 | – | – | – | – |
4 | Lu K (12) | 2022 | Prospective, simultaneous spilt‑face | China | Fractional non-ablative 1,927 nm thulium laser (FTL) 1,927 nm; fractional ablative 2,940 nm Er:YAG laser (FEL) 2,940 nm | 27; 27 | 27 [54] | 16 M 11 F; 16 M 11 F | 26; 26 | – | – | – | GBS, patients’ satisfaction |
5 | Gawdat HI (13) | 2022 | Split-face randomized | Egypt | PRP ‘fluid + fractional CO2 laser; PRP ‘gel + fractional CO2 laser | 27; 27 | 27 [54] | – | – | – | – | – | Clinical assessment scores, ECCA |
6 | Emam AAM (14) | 2022 | Split-face comparative | Egypt | 2,940 nm fractional Er: YAG laser | 21; 21 | 21 [42] | – | – | – | 16 weeks | 3 months | GBS |
7 | Allam N (15) | 2022 | Randomized clinical | Egypt | Monopolar radiofrequency; pulsed dye laser | 15; 15 | 30 | – | – | – | 1 session (8 minutes for each cheek) per month of MFR for 4 months. 1 session (5 minutes for each cheek) per month of PDL for 4 months | – | ECCA, FASQoL (this is a 10-item assessment tool with 3 do-mains for evaluating the emotional, social, and work/school-related effect of scars), SCARS [self-assessment questionnaire (using a scale of 0–10)] |
8 | Sirithanabadeekul P (16) | 2021 | Randomized split-face comparative | Thailand, | Fractional picosecond 1,064-nm laser; fractional CO2 laser | 25; 25 | 25 [50] | – | – | – | 3 months | – | Skin imaging, physician improvement scores |
9 | Shi Y (8) | 2021 | Randomized, split-face, double-blind | China | Fractionated frequency-doubled 1,064/532 nm picosecond Nd:YAG laser; non-ablative fractional 1,540 nm Er: glass laser | 22; 22 | 22 [44] | – | – | – | 4 monthly treatments | 1 month | ECCA, PRIMOS (a 3D imaging system), two physicians (with 15 and 30 years of work experience, respectively), who were blinded to the grouping, evaluated the treatment efficacy |
10 | Rajput CD (17) | 2021 | Prospective, nonrandomized, open-label | India | Fractional CO2 laser; fractional microneedling radio frequency | 25; 25 | 50 | – | – | – | 4 sessions were given for both the groups at an interval of 2 months | – | GBS |
11 | Pratiwi I (18) | 2021 | Double-blind, randomized controlled | Indonesia | Long-pulsed Laser Nd:YAG 1,064 nm + Vitamin C; long-pulsed Laser Nd:YAG 1,064 nm | 9; 9 | 18 | – | – | – | – | – | GBS |
12 | Lan T (19) | 2021 | Pilot randomized Split-face clinical | China | Fractional micro-plasma radiofrequency; fractional microneedle | 60; 60 | 60 [120] | 39 M/21 F | 17–30 (average 22.87 ±2.51) | 3 applications of treatment at 2-month intervals | 1, 3, 6 months after the final treatment | ECCA, dermatologists evaluation, patient self-evaluation, DLQI scores, adverse effects | |
13 | Kimwattananukul K (20) | 2021 | Double-blind, placebo-controlled | Thailand | 0.5% timolol maleate; normal saline; fractional CO2 laser | 25; 25 | 25 [50] | 12 M/13 F | 18–50, mean 31.4 | At least 3 months | – | – | Skin hydration, crusting score |
14 | Feng H (21) | 2021 | Randomized, evaluator-blinded, left-to-right split-face | China | Intense pulsed light; fractional 1,064 nm Nd:YAG picosecond laser + intense pulsed light | 15; 15 | 15 [30] | – | 18–60 | – | – | five sessions of treatment at weeks 0, 4, 8, 12, 16 and were followed up at week 28 | ECCA, DLQI, TEWL, MI |
15 | El-Hawary EE (22) | 2021 | Comparative clinico-immuno-histopathological | Egypt | PRP; ablative fractional CO2 laser; PRP + FCO2 | 20; 20; 20 | 60 [22M/38F] | 40% M/60% F; 40% M/60% F; 30% M/70% F | Aged 20–35 (mean 24.60±3.20) | – | Each group received 3 sessions at monthly intervals | – | Clinical, histopathological |
16 | Cheng X (23) | 2021 | Randomized split-face | China | 10,600 nm ablative fractional laser; 1,565 nm nonablative fractional laser | 19; 19 | 19 [38] | – | – | – | – | – | Erythema, crusting durations, and degree of pain |
17 | Chen L (24) | 2021 | China | 2,940 Er:YAG laser treatment in the microlaser peeling; fractional ablative laser; combined modes | 30; 30; 30 | 90 | – | – | – | – | – | ECCA, self-evaluation of treatment satisfaction by the patient | |
18 | Al-Dhalimi MA (25) | 2021 | Split-face clinical comparative | Iraq | 2,940 nm fractional Er: YAG laser; long pulsed Nd:YAG 1,064 nm laser | 20; 20 | 20 [40] | – | – | – | 3 sessions at a 3-week interval | – | Sharquie scores, digital photographic assessment, patient’s satisfaction |
19 | Abdel-Maguid EM (26) | 2021 | Split-face clinical | Egypt | Fractional CO2 laser + topical SC-CM or fractional CO2 laser + saline; fractional CO2 laser + topical PRP or SC-CM | 17 [34]; 16 [32] | 33 [66] | – | – | – | 3 monthly sessions | – | ECCA, 2 blinded dermatologists |
20 | Sallam MAE (27) | 2021 | Split face comparative | Egypt | Microneedling with PRP; fractional CO2 laser with PRP | 20; 20 | 20 [40] | – | – | – | – | – | GBS |
21 | Wen X (28) | 2020 | Randomized split face, investigator-blinded | China | 755 nm picosecond alexandrite laser fitted with DLA; within-patient control | 16; 16 | 16 [32] | – | – | – | three treatments at 1-month intervals | – | ECCA, CEAS |
22 | Pooja T (29) | 2020 | Randomized | India | Fractional CO2 laser; microneedling; PRP | 20; 20; 20 | 60 | – | Age range of 16–45 | – | Monthly intervals for 4 sessions. | – | GBS |
23 | Mahamoud WA (4) | 2020 | Split face | Egypt | Fractional CO2 laser + PRP; fractional carbon dioxide laser + noncross-linked hyaluronic acid | 30; 30 | 30 [60] | 14 M/16 F | – | – | 3 sessions of full-face fractional CO2 laser re- surfacing | – | GBS grading system, 2 blinded investigators |
24 | Lakkireddygari S (30) | 2020 | Comparitive | India | Fractional CO2 laser; fractional CO2 laser + autologous platelet rich plasma | 40; 40 | 80 | – | – | – | 6 sessions at 1 month intervals | – | Scar score |
25 | Kwon HH (31) | 2020 | Prospective, double-blind, randomized, split-face | Korea | Fractional CO2 laser + human adipose tissue stem cell-derived exosomes; fractional CO2 laser + control gel | 25; 25 | 25 [50] | – | – | – | – | – | – |
26 | Kwon HH (32) | 2020 | Prospective, randomized, split-face, controlled | Korea | 1,064-nm neodymium-doped yttrium aluminum garnet picosecond laser using a diffractive optical element; nonablative 1,550-nm erbium-glass laser | 25; 25 | 25 [50] | 11 M/14 F | Aged 19–37 | – | 3-week intervals | 8 weeks | ECCA, IGA, patients’ reports at the final visit |
27 | Abdel Kareem IM (33) | 2020 | Comparative split face | Egypt | Fractional CO2 laser; fractional CO2 laser + CO2gas | – | – | – | 17–42 | – | – | – | Follow-up photographs, patient satisfaction |
28 | Kaçar N (34) | 2020 | Prospective, split-face, single-blinded, controlled clinical | Turkey | Fractional CO2 lasers; F CO2vs. FRF + fractional radiofrequency | 27; 27 | 27 [54] | – | – | – | – | – | ECCA, patient satisfaction |
29 | Chopra A (35) | 2020 | Comparative | India | Microneedling; fractional CO2 | 30; 30 | 60 | – | – | – | Every 4 weeks for a period of 24 weeks | – | Per quantitative global acne scarring classification |
30 | Chen CJ (36) | 2020 | Split face, randomized controlled | China | Intense pulsed light; pulsed dye laser | 21; 21 | 21 [42] | – | – | – | 2 weeks interval for 4 treatment sessions | – | VISIA data, acne lesion counts, complications, and skin biopsies |
31 | Chayavichitsilp P (37) | 2020 | Randomized, single-blinded, intrapatient, left- to-right comparative | Thailand | Fractional Nd:YAG 1,064-nm picosecond laser; fractional 1,550-nm erbium fiber laser | 30; 30 | 30 [60] | 16 M/14 F | Age ≥18 | – | 4 times at 4-week intervals | – | ECCA |
32 | Arsiwala NZ (38) | 2020 | Hospital-based prospective, double blinded, randomized, and comparative | India | PRP + fractional CO2 laser; fractional CO2 laser | 17; 16 | 33 | 21 M/11 F | 24.36±4.37 | – | – | Follow-up for next laser session every 4 weeks up to 12 weeks | GBS qualitative grading |
33 | An MK (39) | 2020 | Randomized controlled split-face | Korea | Topical poly-lactic acid; microneedle fractional radiofrequency | 36; 36 | 36 [72] | – | – | – | – | – | Acne scar assessment score assessment of patient satisfaction |
34 | Al-Sultany HA (40) | 2020 | Comparative | Iraq | Fractional CO2 laser; MFR | 21; 21 | 42 | 15 M/6 F | 20–48, average 36 | – | Once monthly for 4 months | – | GBS scale |
35 | El-Taieb MA (41) | 2019 | Randomized clinical | Egypt | Fractional erbium-YAG laser; PRP; fractional erbium-YAG laser + PRP | 25; 25; 25 | 75 | – | – | – | – | – | GBS, system clinical, assessment clinical improvement, clinical satisfaction |
36 | Al Taweel AI (42) | 2019 | Comparative | Egypt | Fractional CO2 laser + PRP; carboxytherapy + PRP | 20; 20 | 40 | – | – | – | – | – | Acne scars, patients’ satisfaction |
37 | Abou Eitta RS (43) | 2019 | Single-center, split-face, prospective clinical | Egypt | Fractional CO2 laser; autologous adipose-derived stem cells | 10; 10 | 10 [20] | – | – | – | – | 3 months | GBS, scar area percentage, skin function |
38 | Elsaie ML (44) | 2018 | – | Egypt | Ablative 10,600 nm CO2 lasers; nonablative 1,540 nm erbium doped glass laser | 29; 29 | 58 | 39 M/19 F | Aged 18–45 | – | 4 treatment sessions with a 3-week-free interval | – | 2 blinded dermatologists, subjective assessment |
39 | Dierickx C (45) | 2018 | – | Belgium | Picosecond 755 nm alexandrite laser | 7; 7 | 7 [14] | – | – | – | – | – | 6-point grading score |
40 | Abdel Aal AM (46) | 2018 | Single-blinded, comparative split-face | Egypt | Fractional CO2 laser; PRP + fractional CO2 laser | 30; 30 | 30 [60] | – | – | – | – | 3 days, 7 days, 1 month, and 3 months after sessions | GBS |
41 | Saluja SS (47) | 2017 | Randomized split-face controlled | America | 1,550 nm non-ablative fractional laser; oral isotretinoin | 10; 10 | 10 [20] | – | – | – | – | Blinded dermatologist | |
42 | Osman MA (48) | 2017 | Randomized fplit-face clinical | Egypt | Fractional erbium-doped Yttrium aluminum garnet laser; microneedling | 30; 30 | 30 [60] | 20 M/10 F | Aged 21–41 | – | – | 3 months | Patient satisfaction, clinical assessment |
43 | Min S (49) | 2017 | Prospective, single-blind, and comparative (randomized split-face) clinical | Korea | Er: YAG laser; bipolar radiofrequency combined with infrared diode laser | 24; 24 | 24 [48] | – | – | – | – | – | ECCA, 5-point Investigator’s Global Assessment |
44 | Kwon HH (50) | 2017 | Prospective, randomized split-face | Korea | Non-ablative 1,550-nm Erbium-glass laser + microneedling radiofrequency; microneedling radiofrequency | 28; 28 | 28 [56] | 15 M/13 F | – | – | 16-week | – | IGA, ECCA |
45 | Khamthara J (51) | 2017 | Randomized, split-face, evaluator-blinded, placebo-controlled, comparative | Thailand | Silicone gel; placebo; ablative Er:YAG laser | 19; 19 | 19 [38] | – | – | – | – | – | Subject’s evaluation, physicians’ global evaluation |
46 | Faghihi G (52) | 2016 | Split-face randomized clinical | Iran | Ablative CO2 resurfacing laser + PRP; ablative carbon dioxide resurfacing laser | 16; 16 | 16 [32] | 12 M/4 F | – | – | – | – | – |
47 | Cachafeiro T (53) | 2016 | Randomized clinical | Brazil | Non-ablative fractional erbium laser 1,340 nm; microneedling | 22; 20 | 42 | – | – | – | – | – | Generalized estimating equation, Mann-Whitney test |
48 | Anupama YG (54) | 2016 | – | India | Subcision followed by CO2 laser; CO2 laser alone | 25; 25 | 50 | – | – | – | 4 sessions at 4-week interval | – | – |
49 | Faghihi G (55) | 2015 | Randomized split-face clinical | Iran | Fractional CO2 laser; punch elevation combined with fractional carbon dioxide laser | 42; 42 | 42 [84] | – | – | – | – | – | 2 dermatologists blinded to treatment |
50 | Chae WS (56) | 2015 | Comparative | Korea | 1,550 nm Er:Glass fractional laser; fractional radiofrequency microneedle | 20; 20 | 40 | – | – | – | – | – | ECCA |
51 | Yuan XH (57) | 2014 | Comparison | China | Fractional CO2 laser (20 mJ, density 10% and the other half with 20 mJ, density 20%); Fractional CO2 laser (10 mJ, density 10% and the other half with 20 mJ, density 10%) | 10; 10 | 20 [40] | 10 M/10 F | Aged 22–31 | – | – | – | 2 blinded dermatologists self-assessment |
52 | Rongsaard N (58) | 2014 | Randomized split-face clinical | Thailand | Fractional erbium-doped glass 1,550-nm; fractional bipolar RF | 20; 20 | 20 [40] | – | Aged 18–55 | – | – | – | 3 blinded dermatologists, patients evaluated clinical improvement texture scores |
53 | Leheta TM (59) | 2014 | Randomized controlled | Egypt | PCI + TCA 20%; 1,540 nm non-ablative fractional laser; 1,540 nm fractional laser + PCI + TCA 20% | 13; 13; 13 | 39 | – | – | – | – | – | Scar severity scores |
54 | Ahmed R (60) | 2014 | – | Egypt | CO2 laser without needling; CO2 laser with needling | 30; 30 | 30 [60] | – | – | – | 4 sessions at 3-week interval | 3 months | GBS, acne scar severity index, qualitative scarring grading system |
55 | Zhang Z (61) | 2013 | Randomized split-face clinical | China | Fractional microplasma radio frequency technology; CO2 fractional laser | 33; 33 | 33 [66] | – | – | – | – | – | ECCA, patient satisfaction |
56 | Mohammed G (62) | 2013 | Randomized clinical | Egypt | CO2 laser with needling applied; CO2 laser without needling applied | 30; 30 | 60 | – | – | – | Five times at 2- to 3-week intervals | – | Acne scar severity index, GBS, patient satisfaction evaluation score |
57 | Manuskiatti W (63) | 2013 | – | Thailand | fractional Er:YAG; CO2 lasers | 24; 24 | 24 [48] | – | 22–51 | – | 2 treatments with a 2-month interval | 1, 3, and 6 months after the final treatment | Two blinded medical assessors, Patient Self-Assessment, Scar Volume Assessment |
58 | Lee JW (64) | 2011 | Simultaneous split-face | Korea | Ablative CO2 fractional + PRP; ablative CO2 fractional | 14; 14 | 14 [28] | 4 M/14 F | 28.1 (range, 21–38) | – | – | – | 2 different blinded dermatologists |
59 | Asilian A (65) | 2011 | – | Iran | Q-Switched 1,064-nm Nd:YAG laser; fractional CO2 laser | 32; 32 | 64 | – | – | – | – | – | Patients satisfaction, physicians’ assessment, two blinded dermatologists |
60 | Alexis A (66) | 2011 | Prospective, split-face, randomized, controlled | America | 1,550 nm erbium-doped fractionated laser [40 mJ and treatment level 4 (11% surface area coverage)]; 1,550 nm erbium-doped fractionated laser [40 mJ and treatment level 7 (20% surface area coverage)] | 18; 18 | 18 [36] | – | – | – | – | – | QGSGSS, blinded investigator global VAS, Skindex-16 |
61 | Mahmoud BH (67) | 2010 | Prospective, single-blind, randomized | America | 1,550-nm fractional laser (10 mJ); 1,550-nm fractional laser (40 mJ) | 15 | 3 M/12 F | – | – | – | – | Blinded evaluators | |
62 | Hedelund L (68) | 2010 | Randomized controlled | the UK | 1,540-nm nonablative fractional laser | 5; 5 | 10 | – | 18–60 | – | – | – | Scar texture, skin colour, patients significance |
63 | Cho SB (69) | 2010 | Randomized split-face | Korea | 1,550-nm erbium-doped FPS; 10,600-nm CO2 FS | 8; 8 | 8 [16] | 8 M | Mean 21.3, range 20–23 | – | – | 3 months | Two blinded dermatologists |
64 | Wanitphakdeedecha R (70) | 2009 | – | Thailand | VSP Er:YAG laser (300 micros/1,500 micros) | 12; 12 | 24 | – | – | – | – | 1, 2, and 4 months | Skin smoothness, scar volume |
65 | Min SU (71) | 2009 | Randomized split-face clinical | Korea | Long-pulse Nd:YAG laser; 585/1,064-nm laser + long-pulse Nd:YAG laser | 19; 19 | 19 [38] | ECCA, patient satisfaction | |||||
66 | Lee DH (72) | 2009 | Randomized split-face clinical | Korea | PDL; 1,064-nm long-pulsed Nd:YAG laser | 18; 18 | 18 [36] | ECCA | |||||
67 | Kim HJ (73) | 2009 | Simultaneous split-face | Korea | 1,550 nm erbium: glass fractional laser; chemical reconstruction of skin scars | 20; 20 | 20 [40] | Objective and subjective improvement | |||||
68 | Yaghmai D (74) | 2005 | – | America | 1,064 nm Nd:YAG laser; 1,320 nm Nd:YAG laser | 6; 6 | 12 | Evaluated by photographic and profilometric methods | |||||
69 | Tanzi EL (75) | 2004 | Prospective clinical and histologic | America | Long-pulsed 1,320-nm Nd:YAG; 1,450-nm diode lasers | 20; 20 | 20 [40] | Clinical improvement, patient satisfaction scores |
PRP, platelet-rich plasma; Nd:YAG, neodymium-doped yttrium aluminium garnet; FTL, fractional non-ablative; Er:YAG, Erbium:Yttrium-Aluminum-Garnet; MFR, microneedling fractional radiofrequency; PCI, percutaneous collagen induction; TCA, trichloroacetic acid; FPS, fractional photothermolysis systems; FS, fractional laser system; VSP, variable square pulse; PDL, pulsed dye laser; ECCA, échelle d’évaluation clinique des cicatrices d’acné; DLQI, dermatology quality of life index; VSS, Vancouver scar scale; GBS, Goodman and Baron; CEAS, Clinician Erythema Assessment Scale; IGA, Investigator’s Global Assessment; TEWL, trans-epidermal water loss; MI, melanin index; RF, radiofrequency; SCCM, stem cell-conditioned medium; QGSGSS, Quantitative Global Scarring Grading System Score; VAS, visual analog scale.
Quality evaluation
The included studies were all RCTs. There were 3 methods of random allocation among the included studies: the table of random digits was used in 6 studies, computer software in 8 studies, and sequence generation in 1 study. The remaining studies did not report the method of random allocation. Allocation concealment by using closed envelopes was reported in 4 articles. A total of 25 studies used blinding to reduce performance bias, among which 7 studies used double-blinding and 18 used single-blinding. There were 22 studies that used blinding in outcomes measurement to reduce measurement bias, among which 3 studies used single-blinding, 16 used double-blinding, and 3 used triple-blinding. The number of drop-out patients ranges from one to nine (Figure 2).
Meta-analysis results
Evaluation of scar improvement
The ECCA and GBS methods were used to evaluate the improvement of acne scars. The standard mean difference (SMD) was used in the meta-analysis.
Some 14 interventions were involved in the 18 included studies (1,6,8,10,12,14,15,17,18,26,32,38,40,43,49,50,56,61), among which 6 were combined therapies [1064Nd + 15%VC, Er + RF, 30%SC + FCL, FCL + PRP, FCL + HA, FCL + SC-CM (stem cell-conditioned medium)] and 8 were monotherapies (1064Nd, Er, FCL, MTS, ASC, RF, 1927FTL, PDL). The network demonstrated the direct or indirect relationship between the 14 interventions. A closed loop was formed by FCL, FCL + PRP, and FCL + SC-CM interventions. The number of studies on FCL ranked the first, followed by the number of studies on Er. The number of studies on comparisons between FCL and FCL + PRP was the highest (Figure 3) (laser abbreviations involved in the text are shown in Table 2).
Table 2
Treat | Intervention | Abbreviation |
---|---|---|
Treat 1 | Fractional carbon dioxide laser | FCL |
Treat 2 | 30% supramolecular salicylic acid | 30%SC |
Treat 3 | Monopolar radiofrequency | RF |
Treat 4 | Pulsed dye laser | PDL |
Treat 5 | Er:YAG laser treatment | Er |
Treat 6 | Fractional radiofrequency microneedle | MTS |
Treat 7 | 1,064-nm neodymium-doped yttrium aluminum garnet picosecond laser | 1064Nd |
Treat 8 | Fractional non-ablative 1,927 nm thulium laser | 1927FTL |
Treat 9 | Autologous adipose-derived stem cells | ASC |
Treat 10 | Stem cell-conditioned medium | SC-CM |
Treat 11 | Platelet-rich plasma | PRP |
Treat 12 | Non-cross-linked hyaluronic acid | HA |
Treat 13 | Fractional microneedle | FM |
Treat 14 | carboxytherapy | CO2gas |
According to the SUCRA value, different laser treatments were ranked as follows: FCL + PRP (0.699) > 1064Nd + 15%VC (0.675) > 1064Nd (0.627) > 1927FTL (0.582) > FCL + HA (0.58) > Er (0.576) > Er + RF (0.541) > PDL (0.514) > MTS (0.510) > FCL + 30%SC (0.444) > ASC (0.364) > FCL + SC-CM (0.312) > FCL (0.299) > RF (0.277). It was shown that FCL + PRP (0.699) ranked the first, followed by 1064Nd + 15%VC (0.675). All the interventions were compared with the others using a league table. As shown by Table S2, the improvement of the acne scars was the continuous variable. The confidence intervals (CIs) of most pairwise comparisons included 0, indicating that there was no significance in most pairwise comparisons of the intervention. Compared with FCL, scars were significantly improved after FCL + PRP treatment (SMD: −1.76; 95% CI: −3.49 to −0.03). The ranking of improvement of the acne scars is shown in Table S2. The funnel plot was symmetric, indicating that the publication bias was not significant (Figure 4 and Figure 5).
Cure rate
A total of 13 studies (10,12,24,33,41-44,46,48,50,52,56) reported a cure rate. A total of 12 types of interventions were included, of which 7 were combined therapy (CO2gas + PRP, FCL + CO2gas, Er + FCL, FCL + 30%SC, FCL + PRP, FCL + yifu, Er + PRP) and 5 were monotherapies (FCL, RF, MTS, PRP, ER). A total of 5 closed loops were formed. The sample size of the studies on FCL was the largest, followed by the studies on Er. There were more studies reporting the comparison of FCL and FCL + PR and comparison of FCL and ER (Figure 6).
A ranking table demonstrated the ranking of the cure rates of acne scar by different interventions: Er + PRP (0.873) > FCL (0.773) > FCL + 30%SC (0.772) > FCL + yifu (0.732) > FCL + CO2gas (0.675) > FCL + PRP (0.641) > Er + FCL (0.449) > CO2gas + PRP (0.446) > MTS (0.261) > Er (0.217) > RF (0.106) > PRP (0.057), among which Er + PRP (0.873) ranked the first (Figure 7).
Table S3 presented that the CI in the pairwise comparison of some interventions included 1. Since the cure rates was a categorical variable, this result indicated that the comparison was non-significant. Compared with FCL, the cure rate of FCL + PRP was increased (SMD: 1.64, 95% CI: 1.17 to 2.28). Compared with PRP, the cure rate of FCL + 30%SC was increased (SMD: 23.97, 95% CI: 1.59 to 361.84). Compared with PRP, the cure rate of Er + PRP was increased (SMD: 21.91, 95% CI: 4.02 to 119.41). Other significant comparisons included FCL vs. RF, FCL vs. PRP, FCL + yifu vs. FCL, FCL + yifu vs. RF, FCL + yifu vs. PRP, FCL + yifu vs. MTS, FCL + yifu vs. CO2gas + PRP, FCL + PRP vs. FCL, FCL + PRP vs. RF, FCL + PRP vs. PRP, FCL + 30%SC vs. RF, FCL + 30%SC vs. PRP, Er + PRP vs. RF, Er + PRP vs. PRP, Er + FCL vs. FCL, Er + FCL vs. RF, Er + FCL vs. PRP, Er + FCL vs. MTS, Er + FCL vs. Er, Er + FCL vs. CO2gas + PRP, Er vs. RF, and Er vs. PRP. The ranking of the cure rates of acne scar is depicted in Table S3. The risk of bias of the studies was assessed, revealing that most studies were evenly distributed on both sides of the effect size, indicating that the publication bias was non-significant (Figure 8).
Satisfaction
There were 8 studies (15,16,24,41,42,44,46,52) that reported satisfaction. A total of 8 types of interventions were included, of which 3 were combined therapy (Er + PRP, FCL + PRP, CO2gas + PRP) and 5 were monotherapies (FCL, 1064Nd, Er, PRP, RF). A total of 3 closed loops were formed. The sample size of the studies on FCL was the largest, followed by the studies on FCL + PRP. There were more studies reporting the comparison of FCL and FCL + PRP (Figure 9).
The interventions were ranked according to SUCRA values: FCL (77.2) > PRP (0.649) > CO2gas + PRP (0.530) > Er + PRP (0.524) > FCL + PRP (0.423) > 1064Nd (0.393) > Er (0.364) > RF (0.346) (Figure 10).
The pairwise forest plot and Table S4 showed the comparison between any 2 interventions (Figure 5). The CI of all the comparisons included 1. Since satisfaction was a categorical variable, the results indicated that all the comparisons were non-significant.
The funnel plot presented that the distribution of the studies was mostly symmetrical, indicating a non-significant publication bias (Figure 11).
For the safety of each laser intervention method, there will be a certain degree of complications, such as erythema, edema, pigmentation, exudation, purpura, pain, and so on. These complications are diverse, and the complications of different intervention methods are also different, which can not be uniformly evaluated.
Discussion
There are various options for treating acne scars. Laser treatment, a non-invasive method, has gradually become a mainstream choice with the maturity of optoelectronic technology and the invention of various laser devices. Therefore, we conducted this network meta-analysis to directly or indirectly compare the effects of multiple interventions on acne scarring. A focus of this study was to determine the most effective methods of treating acne scars. The top 3 treatments were Er + PRP, FCL monotherapy, and FCL + 30%SC. The most effective method was Er laser + PRP, which might be attributed to the 2 modes of Er (short-pulsed and dual-mode Er:YAG) (76). Furthermore, the commonly used wavelength of Er laser is 2,940 nm, and its peak absorption coefficient of Er for water is higher than that of FCL (48). A previous meta-analysis compared FCL and Er laser and found that there was no significant difference in efficacy between the 2 devices and both were effective in the treatment of acne scarring (77). This is also the reason why acne scars can be effectively treated. PRP has a synergistic effect with Er to maximize the cure rate. Currently, there is a lack of meta analyses comparing Er with other laser treatments. A 30% salicylic acid concentration can increase the efficacy of FCL, which may reduce the repeat times of laser treatments. This indicates that salicylic acid can achieve better therapeutic effects with fewer laser treatments. The economic burden can be reduced for patients without increasing pain and adverse reactions (6). However, this study found that there was no difference in the cure rate between FCL and FCL + 30%SC, indicating that 30%SC might only be advantageous in increasing the efficiency of laser for 1 time. The cure rate of FCL could not be increased generally. This result should be validated by further research with extended follow-up time and larger sample size. As for the improvement of acne scarring assessed by ECCA and GBS scales, the top 3 treatments were FCL + PRP, 1064Nd + 15%VC, and 1064Nd monotherapy. There were RCTs (22) and meta-analyses (78) showing that FCL + PRP was better than FCL monotherapy in treating acne scars. There were also meta-analyses comparing FCL with other treatments (9). FCL + PRP has gradually become one of the most important treatments for acne scars. However, there is a lack of meta analyses comparing FCL + PRP with other treatments. Therefore, there is no evidence on the relationship between FCL + PRP and other treatments to support the results in our study. There were RCTs demonstrating that 1064Nd had the same efficacy as FCL in the treatment of atrophic acne scars (16). Although they were both combined therapies, this study showed that FCL + PRP had better effects on the improvement of acne scars compared with 1064Nd + 15%VC. In the treatment for atrophic acne scars, long-pulse Nd:YAG 1064 nm laser + 15% vitamin C solution (ascorbic acid) was more effective in reducing GBS scores compared with long-pulse Nd:YAG 1064 nm laser monotherapy, which was consistent with the results in our study. However, no study had investigated whether there is difference in the efficacy between the combined therapy and 1064Nd monotherapy (18). This requires extensive long-term research for more comprehensive results. According to our analysis, in terms of patient satisfaction, the top 3 treatments were FCL, PRP, and CO2gas + PRP. A previous meta-analysis compared FCL with other laser treatments and the results showed that the efficiency of FCL was much higher than that of other treatments (9) in treating acne scars. The improvement of appearance was a key reason for increased patient satisfaction. The cure rate of FCL was less than that of FCL + PRP (26). However, intradermal injection into the inflammatory skin (due to prior treatment with FCL) could lead to worsening pain (22), which might greatly influence patient satisfaction. Patients may ignore the treatment effect due to intense pain and feel more satisfied with FCL monotherapy. Efforts are still required to balance the treatment effect and adverse reactions in clinical practice. Although PRP is a non-laser method and its efficacy is inferior to that of laser treatment or combination therapy, it has the advantages of simple operation, short recovery time, and low cost compared with other non-laser treatment (22). These benefits are the reasons why patients prefer PRP treatment. A previous study has also demonstrated that although the efficacy of CO2gas + PRP was worse than that of FCL + PRP, the complications of CO2gas + PRP were less compared with FCL + PRP, which led to significantly higher satisfaction of patients who received CO2gas + PRP (42).
There were some limitations to our study. On the one hand, the present study did not explore whether various treatments have varied therapeutic effects on patients of different genders, skin colors, and skin types. According to a report, women visit dermatologists for acne scars more frequently than men, and darker skin is more likely to cause complications (43). Furthermore, the effect of laser treatment varies on patients with different skin types. For instance, CO2 laser is more effective for rolling and boxcar scars than icepick scars. (boxcar scars are round or oval sunken scars that have relatively sharp edges with a diameter of 1.5 to 4 mm; rolling scars are wavy, greater than 4 mm in diameter, and have soft edges; icepick scars feature a V-shape, deep lesions, a diameter of less than 2 mm, and sharp edges) (4). However, the included studies did not classify patients by gender, skin color, and skin type. On the other hand, the follow-up duration in the included studies was relatively short. A study has reported an increase in the quantity and density of collagenous fiber in the dermal papilla for up to 8 weeks after laser treatment. Therefore, there may be a difference in the data obtained.
Conclusions
Combination therapy is recommended for acne scars. The combination of Er with PRP has the highest cure rate for acne scars, followed by FCL combined with 30%SC, or single FCL. FCL in combination with PRP improves acne scars most significantly, and 1064Nd combined with 15%VC is also effective. In contrast, patients prefer single treatment, with single FCL as the most satisfying option, followed by single PRP. This may be associated with their feelings about treatment, side effects, and costs. Therefore, Er + PRP and FCL + PRP can be used as the first choice for clinical treatment of acne scars. Additionally, using FCL alone is also an effective and elective treatment method due to its affordable cost and comfort.
Acknowledgments
Funding: None.
Footnote
Reporting Checklist: The authors have completed the PRISMA-NMA reporting checklist. Available at https://atm.amegroups.com/article/view/10.21037/atm-22-5997/rc
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