Use of radiofrequency in the treatment of acne: a systematic review

ABSTRACT Acne, of great prevalence and impact, presents many forms that can be treated by hygiene, topical medications, and manual alternative interventions such as skin cleansing and electrotherapy. The use of radiofrequency in the treatment of acne aims to increase the temperature in the cutaneous tissue, causing several metabolic and structural reactions, such as stimulating neocollagenesis. This study aimed to investigate the use of high-frequency current as an adjunctive treatment for acne. This is a non-systematic review of indexed databases (MEDLINE, SciELO, LILACS). A total of 18 studies were included in this review and most of them related different treatment for acne associated with radiofrequency. Radiofrequency presents few complications and good results, besides having as an additional advantage the possibility of the patient returning to the routine immediately after application.


INTRODUCTION
Acne is one of the most prevalent skin diseases, especially in the young population, peaking from 14 to 17 years in girls, and from 16 to 19 years in boys, but may also manifest in adulthood.About 80% of the adolescent population suffers from some type of acne during life 1 .
The pathophysiology of acne is characterized by changes in sebaceous hyperplasia and keratinocytic activity of the hair follicle due to hormonal influences commonly present in adolescence.These alterations promote follicle colonization by Propionibacterium acnes and Staphylococcus albus 2 bacteria, responsible for the formation of free fatty acids with pro-inflammatory properties, culminating in the inflammatory/immune response that originate comedones and pustules, which can evolve to atrophic scars 3 .
As consequence, acne can lead to a psychosocial impact, influencing daily activities and social relationships.Significant levels of anxiety and depression have already been observed in patients with this disease 4 .
Despite the high prevalence and impact of acne, there are many forms of treatment available that vary according to the degree of involvement and may involve hygiene measures, topical (benzoyl peroxide) and oral (isotretinoin and tetracycline) medications, and manual alternative interventions such as skin cleansing and the use of electrotherapy 5,6 .
In electrotherapy, radiofrequency aims to increase skin temperature, causing several metabolic and structural reactions, stimulation of neocollagenesis, skin retraction, and increased blood and lymphatic circulation (improving skin nutrition) 7 .Among other benefits, bactericidal, decongestant, regenerating, and healing effects can be highlighted.
Considering the number of studies on this theme in the literature, a systematic review is necessary to answer whether radiofrequency treatment is effective in the treatment of acne.As radiotherapy is a resource widely used in dermatological treatments, and can be associated with different techniques-including the treatment of other diseases-this systematic review aims to investigate the use of high-frequency/ radiofrequency current as an adjuvant in the treatment of acne.

METHODOLOGY
This research is a systematic review.The papers used were obtained by searching indexed databases (MEDLINE, SciELO, LILACS).The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 8 protocol.A review protocol was published in the International Prospective Register of Systematic Reviews (PROSPERO CDR42021244409).

Search strategy
The search for articles was performed by the keywords obtained in the Medical Subject Headings (MeSH) and other search terms.In the search, the following keywords were used: "Acne" and "Radiofrequency" for titles and/ or abstracts.
The search and selection of the studies were completed using the PICOS strategy: Population (P), Intervention (I), Comparison (C), Outcome (O), and Study Design (S).The search strategy was defined with the help of MeSH and the terms were allocated in each category according to their search characteristic: P -Adults, I -Radiofrequency, C -Laser, O -Scar treatment, S -Randomized and non-randomized clinical trials.

Selection criteria and study eligibility
The search filters used were: articles published in the last 10 years; in Portuguese or English, and that were available in the full version online.Initially, 34 articles were found.As inclusion criteria, articles should be clinical trials and the theme should be related to the research objective, that is, articles addressing the use of radiofrequency in the treatment of acne.The eligibility criteria for the studies are presented below.

Population
Healthy patients who did not present any dermatological or other disorders, except acne scars, were included.The following patients were excluded: patients with diabetes; pregnant or breastfeeding; with active acne keloids; cancer lesions; warts or skin infections in the area to be treated; viral herpes infections in the previous six months; those who have had topical exfoliation treatments in the past two months; who have taken photosensitizing medications or oral retinoids in the past eight months; who have undergone surgical treatments or orthotherapy; who have received local injections in the previous eight months; who have had photorejuvenation treatments with other sources or photodynamic therapy with aminolevulinic acid (ALA) one year before; who have undergone acne scar treatment during the previous six months; and who have collagen disease or autoimmune disease.

Intervention/exposure
The use of bipolar radiofrequency, fractional microplasma, micro-plasma, or micro-needling devices was required.Some studies have also used fractional CO 2 lasers, fractional 1,550nm lasers (erbium glass), ablative fractional lasers, or non-ablative fractional lasers.

Comparison/control
Studies that used radiofrequency and laser of different models, but did not use a placebo as a control, were included.

Outcomes
Outcomes were presented after one to five treatment sessions and follow-up visits were made one to six months after the end of treatment.The effects of radiofrequency therapy evaluated were the regeneration and healing of acne sequelae.In one study, improvement in acne scars was observed in different regions of the body (face, shoulders, and back).

Study design
Randomized and non-randomized clinical trials were selected, including crossover, single, or doubleblind studies.

Data analysis
The data were used to analyze improvements in acne scarring via photographs taken before and after treatment and were quantified using the ECCA (echelle d' evaluation clinique des cicatrices d'acné) grading system.Months after the treatment, patients were asked to characterize their overall level of satisfaction as very satisfied, satisfied, slightly satisfied, or dissatisfied, separately evaluating each treated region.

Analysis of the quality of articles
The quality of the selected articles was evaluated via the questionnaire produced by Downs and Black 9 , which consists of 27 items divided into five domains: "Reporting" assesses whether the information provided is sufficient; "External validity" verifies the extent to which the study can be generalized to the population studied; "Bias" analyzes the bias in the intervention and results; "Confounding" evaluates the bias in the subjects selection; and "Power" verifies if the results were by chance.The answers are: "Yes" (value 1), "Partially" (value 1), "No" (value 0), and "Unable to determine" (value 0), and the higher the value, the better the quality of the paper.The studies were classified as: poor (<14), regular (15-19), good (20-25), or excellent (>26), according to their score.
The quality of the papers, determined via the Questionnaire of Downs and Black 9 , resulted in one article being classified as poor, five articles as regular, and 12 articles as good.Each article was studied in duplicate by two members of the research team.

RESULTS
Based on the specifiers and terms used for the search, 34 articles were found for this review.These articles were analyzed and three duplicate articles were found; five articles that were related to other diseases, despite addressing the use of radiofrequency; and eight others that were not original articles (systematic reviews and pilot study) (Figure 1).At the end of this analysis, 18 articles met the inclusion criteria (Chart 1).Chart 2 shows the classification of the quality of the studies.The patients showed clinical improvement.Patients' selfassessments corresponded with physicians' evaluations.Histological analyses showed significant improvements in elasticity and melanin/erythema index, along with increases in procollagen levels types I and III, as well as elastin levels.There were no cases of hyperpigmentation, and adverse events were only mild.The subjective evaluations of patients regarding the improvement of seborrhea were similar between the two devices, while those of acne, skin texture, and acne scars were more satisfactory with the use of MRF.For the safety profile, no significant difference was observed between the two regimens, while mild postinflammatory hyperpigmentation was observed only on the LD side.The side effects of both devices were pain, transient facial erythema, and crust formation.
The pain score was higher in laser treatment, but the duration of skin flaking was shorter.One case had post-inflammatory hyperpigmentation on the laser treated side only.Fractional BR and laser have similar efficacy for the treatment of atrophic acne scars.

Ablative fractional laser
Fractional ablative microplasma RF: 27.5kHz, with variables from 10 to 100Hz Four treatment sessions at threeweek intervals Follow-up two and six months after the final session To determine the efficacy and safety of high-potency unipolar radiofrequency in the treatment of acne scars over a short-term period of two months and a long-term period of six months.
The bimodal procedure is safe and effective in reducing acne scars.Significant improvement was observed in the scars, both on the face (P<0.0001) and on the back and shoulders (P<0.0001).