The efficacy and safety of microneedling with topical tranexamic acid for melasma treatment: A systematic review and meta‐analysis

Microneedling with topical tranexamic acid (TXA) is a novel treatment option for melasma; however, the efficacy and safety of this combined administration therapy is in controversial. This study is conducted to address this issue of this technique in melasma.

Melasma is one of the most common acquired pigmentary disorders, which is characterized by symmetric hyperpigmentation, and manifested as brown macules and patches on sun-exposed areas of the face and neck.Although melasma will not lead to serious medical complications, it will lead to serious cosmetic disfigurement, psychological stress and stigma, affecting the quality of life of patients. 1lasma affects all races, but is dominant among Hispanic, Asian and African-American women, especially population with darker skin, corresponding to Fitzpatrick skin types IV-VI, 2 and the prevalence rate varies from 5% to 46% according to the surveys in Iran, Pakistan and Fance. 35][6] Melasma is not only about melanin and pigmentation, it is also associated with an increased dermal vasculature and up-regulation of proangiogenic factors induced by UV irradiation. 7,8Various therapeutic modalities, such as depigmenting agents, laser ablation, and chemical peels, have been used to alleviate melasma to some extent.However, there is no universally effective procedure or drug that can ensure satisfactory results. 5,6anexamic acid (TXA) is a synthetic lysine analogue mainly developed by Japanese scientists and widely used due to its anti thrombotic and anti fibrinolytic properties. 9It effectively reduces melanogenesis in melanocytes and inhibits UV-induced pigmentation in guinea pigs, 10 although the exact mechanism of TXA in reducing melasma hyperpigmentation is still being studied.A large number of studies have shown that oral and local administration of TXA in the treatment of melasma has good efficacy and tolerance, 11,12 our earlier meta-analysis also corroborated these findings. 13Some novel methods, such as intradermal by microinjection or transepidermal by microneedling (mesotherapy), have captured the attention of clinicians due to the potential of adverse events caused by oral use and the low permeability of topical use.
Microneedling is a minimally invasive technique that produces micro perforations in the skin, which has been proven to enhance the percutaneous delivery of local drugs. 14Some studies 15,16 tried to prove the effectiveness and safety of microneedling combined with various drugs (such as vitamin C, hydroquinone) in the treatment of melasma, the results are encouraging.However, the efficacy and safety of microneedling combined with topical TXA vary across the current clinical trials.Furthermore, the differences between microneedling combined with topical TXA and other treatments are controversial.Therefore, the purpose of the present systematic review and meta-analysis was to provide ample evidence for the two aforementioned issues.

| Literature search
The following electronic databases: PubMed, Cochrane Central Register of Controlled Trials, Embase, and Web of Science were extensively researched, using the keywords "melasma", "microneedling", and "tranexamic acid" without any language restrictions.We also screened the reference lists of cited studies for eligibility.The initial inquiry was performed on March 4, 2023, and updated on May 22, 2023.

| Selection criteria
The inclusion criteria were as follows: in English, full-text available, reporting at least one of the primary endpoints of interest, randomized controlled trials (RCT), or prospective comparative studies on microneedling with topical TXA for melasma, regardless of the medical treatments in the control group.The studies involving microneedling with oral TXA, or radiofrequency microneedling in experiment group; as well as other retrospective study, case report, or review were excluded.After excluding duplicates, one reviewer screened the titles and abstracts to eliminate ineligible studies.
Next, we obtained and identified the full-text of all potentially eligible studies according to the predefined selection criteria, with disagreements resolved by discussion.

| Quality assessment of the included studies
According to the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions, the Cochrane Risk of Bias Tool 2.0 17 was used to assess the quality of the potentially eligible RCTs, and non-randomized studies of interventions (ROBINS-I) tool 18 for non-randomized studies by two reviewers independently.If discrepancies exist, a third reviewer was consulted for consensus.

| Outcome measures and data extraction
The primary outcome was a reduction in melasma severity, as measured by the Melasma Area Severity Index (MASI) and its variants (mMASI, hemiMASI), such as; (1) Reduction in melasma severity from baseline to each time point in patients receiving microneedling with Corresponding authors were contacted via email for any missing information if required.

| Statistical analysis
The systematic review and meta-analysis was conducted following the PRISMA guideline, 19 using Review Manager (RevMan, version 5.4, the Cochrane Collaboration, 2020).Before conducting data synthesis, data acquired from studies were preprocessed in Microsoft Excel.The mean differences (MDs) and 95% confidence intervals (CIs) were calculated for the reduction of melasma severity scores from baseline to each time point.In contrast, the standard mean differences (SMDs) and 95% CIs were calculated for the differences in reduction in melasma severity scores between the experimental and control groups at each time point.Statistical heterogeneity was tested using the Chi-squared test or I 2 statistic (I 2 > 50% or p < 0.10).In the absence of heterogeneity, effect estimation was performed using a fixed-effect model; otherwise, a random-effects model was adopted.Subgroup analyses were conducted based on the control group's various time periods and treatments.Sensitivity analysis was conducted based on the randomized split-face and randomized controlled studies.Publication bias was assessed with funnel plots.A p-value of <0.05 indicated statistical significance.

| Quality assessment
Tables 2 and 3 summarize the results of included studies' methodological quality and bias risk.Of all the randomized clinical trials, 11 studies were relatively well-designed (modified Jadad scale scores were at least 4).Of all, the randomization methods were described in nine studies (9/11).Six studies reported blinding details (6/11), and the allocation concealment method was described in 4 of 11 (Figures S1 and S2).The risk of bias in non-randomized investigations is assessed using the ROBINS-I tool, of which 2 studies were low overall risk of bias, and 3 studies were moderate overall risk of bias.The funnel plot shows trials scattered symmetrically around the pooled SE (MD), indicating a low publication bias (Figure S3).

| Meta-analysis of efficacy according to treatment time
Based on all study types, the improvement in melasma severity scores among patients receiving microneedling with TXA increased over time (Figure 2).The changes in the MASI/mMASI/ hemiMASI score after 4 weeks of treatment were reported in seven studies; Moreover, the meta-analysis based on the mean and standard deviation of each time point revealed a statistically significant decrease in melasma severity score (overall effect, MD = 3.45, 95% CI = 2.78-4.12,p < 0.001) in the microneedling plus topical TXA group (Figure S4).
Interestingly, the pooled results based on each group's mean and standard deviation were insignificant, regardless of the overall effect or each time point (Figure S5).S6).Concerning the difference in reduction of melasma severity score between the two groups, the sensitivity analysis revealed a statistical overall effect (SMD = 1.26, 95% CI = 0.63-1.90,p < 0.001), and the reductions of melasma severity score at 12 and 16 weeks in the experimental group were more than those in the control group (Figure S7).Furthermore, the results of sensitivity analysis based on the mMASI also revealed a statistically significant reduction in patients after receiving microneedling plus topical TXA treatment (overall effect, MD = 3.44, 95% CI = 2.64-4.23; Figure S8) and also a statistically bigger improvement in microneedling plus topical TXA group compared with other treatments (overall effect, SMD = 1.29, 95% CI = 0.54-2.03, Figure S9).

| Subgroup analysis
Three studies 12,22,34 effect, SMD = 1.94, 95% CI = 1.02-2.87;Figure S10).Due to less skin trauma, less pain, and shorter treatment sessions, patient satisfaction and tolerance of microneedling were higher. 22,34ree studies 20,24,26 S12), however, microneedling with TXA resulted in significantly higher patient-reported improvement scores. 24,26o studies 23,28 demonstrated that the combination of microneedling and 4% TXA did not differ from 4% hydroquinone (HQ) in melasma treatment.Considering the pain and expense of microneedling, topical HQ could achieve minimal, non-significantly higher patient satisfaction, except for a higher frequency of postinflammatory hyperpigmentation.Two trials 25,29 demonstrated that microneedling, fractional CO 2 laser or QS Nd: YAG laser have equivalent efficacy and safety in delivering TXA for treating facial melasma.In the study by Gharib et al., 27 the authors made a conclusion that microneedling with PRP is superior to microneedling with TXA for treating melasma, because of lower MASI score after three sessions of treatment (4.21 ± 2.06 vs. 6.83 ± 3.11, p = 0.02).Batra et al. 30 suggested that oral and transepidermal TXA appear to be equally effective, whereas transepidermal TXA therapy has the advantage of local action, thereby avoiding systemic side effects.However, it is less convenient for the patient and slightly painful.

| Side effects and adverse events
All included investigations demonstrated that microneedling was well tolerated.Common side effects included erythema (56.36%), mild pain (41.27%), irritation at the microneedling site (19.64%),postinflammatory hyperpigmentation (6.67%), and transient burning and itching (7%).The adverse events in patients receiving oral TXA were more common and severe than that in patients receiving microneedling, such as, gastrointestinal reaction; and two patients reported epigastric discomfort in the trial we included.topical TXA may produce a better whitening effect than other routine treatments.
Melasma is a distressing, difficult-to-treat skin condition with high recurrence rates.Although the exact molecular mechanism remains unclear, the epidermal hyperpigmentation, increased dermal vascularity and expression of angiogenic factors were believed to play a vital role in melasma. 74][35][36][37] TXA is available in topical, intralesional, and oral formulations, 38 among which oral TXA was found to be the most effective, particularly in cases of refractory melasma.Due to the drug's pro-thrombotic nature, oral TXA has the possibility to cause a gastrointestinal reaction and menstrual irregularities in many patients; therefore, further consideration must be given before prescription.Topical TXA was also a common method to treat melasma because of the superior safety and better tolerance than hydroquinone, while the efficacy was not very satisfied.
As concerns regarding the systemic side effects caused by oral TXA and the low efficacy of topical TXA alone, more clinicians and patients are inclined to use this drug in combination with other means, such as microneedling, intradermal injections, and lasers, which can enhance the topical drug's local permeability to improve outcomes.Compared with microinjection and laser, microneedling is less invasive and painful.Typically, a topical anesthetic is administered 30-60 min before microneedling, followed by microneedling before and after topical therapy, mostly at 2-4 weeks intervals.The procedure is often performed with 1.5 mm needle, causing 0.1-1.5 mm penetration depths, based on the treated anatomic location and pressure applied. 12,39croneedles are applied to the skin with the drugs can not only transport active ingredients through the stratum corneum, but also generates multiple micropunctures with bleeding, which could stimulate the wound-healing response, thereby initiating neocollagenesis and neo-elastogenesis. 40,41Two studies 37,42 demonstrated that microneedling with 5% TXA improves pigmentation and erythema, presented as significantly smaller melanin index (MI) and erythema index (EI), bigger improvement in physician assessments, and higher patient satisfaction with minimal side effects.Cassiano et al. 40 compared microneedling with oral TXA and other treatments, demonstrating that TXA and microneedling act through two distinct pathways to alleviate melasma, with microneedling TA B L E 2 Quality assessment of randomized controlled studies according to the Cochrane Risk of Bias Tool ("Unclear, lack of information or uncertainty over the potential bias").
providing longer-lasting remission than standard therapy.In order to increase the drug concentration at target melanosomal cells in the stratum basal layer of the epidermis and decrease incidence of adverse events, more and more novel microneedles, such as liposomes, trans-ethosomes, biocompatible polymers, and dissolving microneedles have been explored and developed. 43,44Therefore, more details of microneedling are to be uncovered in future, such as the most appropriate material, depth, strength, frequency, and best course of microneedling for treating melasma; as well as the therapeutic difference of different TXA regimens.

F I G U R E 2
Forest plot demonstrating improvement in melasma severity in patients receiving topical tranexamic acid with microneedling over time across studies, based on randomized split face, non-randomized split face, and randomized controlled studies.
There are some limitations in the current study.First of all, not all the studies included in this meta-analysis are RCTs, and the sample size in each trial is insufficient, resulting in substantial heterogeneity.Nevertheless, to date, this meta-analysis is the most comprehensive on this topic.We have included as many trials as possible to obtain the largest sample size, and evaluated their quality and bias using various systems, which revealed that all the trials we adopted are of relatively high quality; and the sensitivity analysis produced the same results.Furthermore, more well designed with large sample RCts are needed to confirm the results.
Second, the evaluation methods and followed-up time points were not thoroughly consistent in the included studies.Of all the  46 The new scoring systems were simple, and all were representatives of melasma severity.In our study, we calculated and analyzed the deduction of each variation to express real results.Moreover, because mMASI was adopted in most of the included studies (9/16), sensitivity analysis was conducted to exclude the influence of other variations.

F I G U R E 3
Forest plot demonstrating a comparison of improved melasma severity in patients receiving topical tranexamic acid with microneedling compared to other therapy over time, based on randomized split-face, non-randomized split-face, and randomized controlled studies.
Third, subgroup analyses of some treatment duration and control groups were not performed due to insufficient included studies.We selected the most common duration and control groups for analysis, which are clinically viable.Moreover, due to the insufficient sample number and the ambiguity of inclusion criteria in studies from African, Latin-American or some other regions which have diverse races and skin colors, no further subgroups analysis were able to be performed to explore the efficacy difference between different skin tones.In the future, further studies may be needed to answer this question.
Last, data synthesis on side effects and adverse events was not conducted, because of the scarce occurrence.The most common side effects are local irritation and discomfort, which are often transient.In spite of the above mentioned shortcomings, the current systematic review and meta-analysis provided specific efficacy and safety evidence of microneedling plus topical TXA for melasma treatment.

| CON CLUS ION
This systematic review and meta-analysis indicated that microneedling with topical TXA is an efficacious and safe therapy for adult melasma.For patients with melasma refractory to routine therapies, the combination therapy of microneedling and TXA may produce unexpected effects.Clinicians should consider adding microneedling as a step-up option before topical TXA alone.

ACK N OWLED G M ENTS
Sincere thanks should be given to my daughter for her support.We thank Home for Researchers editorial team (www.home-for-researchers.com)for language editing service.

FU N D I N G I N FO R M ATI O N
The manuscript was funded by the Technological innovation R&D project of Chengdu Science and Technology Bureau (2022-YF05-01836-SN).

CO N FLI C T O F I NTE R E S T S TATE M E NT
No conflicts of interest have been declared.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are openly available in Jinwei Xie at https://www.researchga te.net/.

E TH I C A L A PPROVA L
Not applicable.

PATI E NT CO N S E NT S TATE M E NT
Not applicable.

PE R M I SS I O N TO R E PRO D U CE M ATE R I A L FRO M OTH E R S O U RCE S
Not applicable.

35 FENG
et al. topical TXA; (2) Difference in improvement in the severity of melasma between patients treated with topical TXA and microneedling versus other treatments at each time point.According to the "PICO" principle, the following information of each included studies were extracted from each eligible study, which included first author, publication year, country, study design, characteristics of population (sample size, age, and gender), interventions and controls (dose of TXA, details of microneedling procedure, duration, and the treatment in the control group), outcomes (MASI, mMASI, or hemi MASI at each predefined time points, any reported side effects or adverse events).
Sensitivity analyses were conducted based on the study type to address the substantial heterogeneity.The results demonstrated a significant decrease in melasma severity score from baseline with the use of microneedling plus topical TXA, no matter the overall effect (MD = 3.57, 95% CI = 2.82-4.32,p < 0.001) or each time point (Figure compared microneedling with topical TXA to microinjections with TXA; the pooled analysis suggested that intradermal microinjections with TXA were more effective (overall F I G U R E 1 Preferred reporting items for systematic reviews and meta-analyses (PRISMA) flow diagram of literature selection.TA B L E 1 Characteristics of included studies.
compared microneedling plus TXA with microneedling alone.The pooled results demonstrated a more significant reduction in melasma severity score (overall effect, SMD = 3.10, 95% CI = 0.81-3.58; Figure S11) in the combined group compared to microneedling alone or with placebo.Four studies 21,31-33 compared microneedling plus topical TXA with microneedling plus vitamin C, and the results demonstrated that the addition of TXA or vitamin C to microneedling had comparable efficacy in reducing the severity of melasma (overall effect, SMD = 0.24, 95% CI = −0.70 to 1.19; Figure