The efficacy and safety of microneedling combined with tacrolimus versus tacrolimus monotherapy for vitiligo treatment: a systematic review and meta-analysis

Abstract

Tacrolimus is a topical immunomodulator that has been used successfully in treating vitiligo; however, recent studies suggested that combining tacrolimus with microneedling (Mn) can increase its efficacy. This systematic review aimed to assess the efficacy and safety of Mn combined with tacrolimus to treat localized and stable nonsegmental vitiligo. We searched Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL). The risk ratio (RR) was used to represent dichotomous outcomes, whereas the odds ratio (OR) was used for adverse events. Three randomized control trials (RCTs) (n=148 participants) were deemed eligible. The pooled effect estimate showed a statistically significant higher re-pigmentation rate in all assessed body areas in favor of treatment with Mn combined with tacrolimus (RR=2.02, 95% confidence interval [CI]: 1.51-2.70). Nonetheless, no significant difference was found between Mn combined with tacrolimus and tacrolimus monotherapy in terms of 5-grade re-pigmentation scale (RR=0.93, 95% CI: 0.53-1.62), histopathological assessment (RR=0.90, 95% CI: 0.47-1.75), and adverse events (OR=1.72, 95% CI: 0.10-29.36). Mn combined with tacrolimus showed a clinically and statistically substantial improvement in the re-pigmentation of vitiligo sites with acceptable tolerability and safety profile.

Introduction

Vitiligo is an autoimmune, disfiguring skin disease that manifests as a non-scaly, amelanotic, chalky-white macule with distinct margins.¹ According to the international consensus, vitiligo is classified into two major classes: nonsegmental vitiligo (NSV) and segmental vitiligo (SV), as they differ in their prognostic implications.¹ Worldwide, vitiligo is a common disease with an estimated prevalence of 0.5-2% in both the adult and pediatric populations.² Studies showed that vitiligo burden extends to patients’ self-esteem and quality of life.^3,4 Over the years, various treatment modalities have been introduced to treat vitiligo, including topical corticosteroids, topical immunomodulators, phototherapy, surgery, and combined therapy.¹ However, vitiligo appears to be difficult to treat, and satisfactory outcomes are challenging to achieve since treatment options cause some adverse events, carry a recurrence depigmentation rate, and appear to be resisted by some individuals.^5-7 Combining tacrolimus with microneedling (Mn) is one of the novel proposed methods to treat localized and stable nonsegmental vitiligo, which is defined as the absence of new lesions or the absence of an increase in the size or number of the current lesions throughout 12 months.^8-11 Although a previous study examined the efficacy of Mn combined with other local therapies, objective assessment, as well as details about pattern and time of re-pigmentation, were not addressed. Also, published literature lacks a systematic evaluation of the safety of Mn combined with tacrolimus.¹² Thus, we prepared this systematic review and meta-analysis to address this knowledge gap by comprehensively evaluating the efficacy and safety of Mn combined with tacrolimus versus tacrolimus monotherapy for localized and stable nonsegmental vitiligo.

Materials and Methods

This systematic review was conducted in compliance with a pre-specified protocol registered in PROSPERO (CRD42022375496) and reported in the light of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist.¹³

Eligibility criteria

The eligibility criteria of our systematic review were randomized control trials (RCTs) that compared combined tacrolimus with Mn to tacrolimus monotherapy in adults and pediatrics with an established diagnosis of vitiligo. Vitiligo is categorized as local and stable nonsegmental vitiligo, defined as the absence of new lesions or the absence of an increase in the size or number of the existing lesions over 12 months. The pre-specified outcomes were the 5-grade re-pigmentation scale or Physician’s Global Assessment (PGA), histopathological assessment, body site re-pigmentation, and adverse events. We excluded trials that included participants with concurrent use of other topical, conventional systemic, or biological therapies.

Search strategy

The systematic search was performed using the Medline, Embase, and CENTRAL databases via Ovid without restriction on language or data. The last search was conducted on November 14, 2022, and included terms related to vitiligo, specifically “vitiligo” and “extra-facial vitiligo”. These were combined with terms for the intervention of interest, including “tacrolimus”, “topical tacrolimus”, “tacrolimus monotherapy”, and “macrolactams”. To identify studies involving adjunctive procedures, terms such as “microneedling”, “dermapen”, and “dry needling” were included. Finally, the search was limited to randomized controlled trials and clinical trials by using both MeSH terms and key words related to study design. The final results included studies that combined the concepts of vitiligo, tacrolimus-based treatments, needling techniques, and clinical trial methodology.

We manually screened the reference list of the included RCTs for any related trials missed during the systematic search.

Study selection and data extraction

Two reviewers performed eligibility screening of titles and abstracts, full-text assessment, and data extraction from eligible trials independently and in duplicate. Any disagreement was resolved by consensus or discussion with the supervising author.

Meta-analysis

Data were analyzed using RevMan (Review Manager) version 5.3 (Cochrane Collaboration) and the random-effects model. I² and p-value of the chi-squared test were used to assess statistical heterogeneity. We used a 95% confidence interval (CI) and a threshold of p<0.05. The risk ratio (RR) was used to represent the dichotomous outcomes: PGA, histopathological assessment, and body site re-pigmentation, whereas the odds ratio (OR) was used to represent the dichotomous outcome: adverse events. The data were pooled using the inverse variance weighting method. The ordinal outcomes were dichotomized by performing subgroup analysis as follows: i) PGA: 0%, 1-50%, 50-75%, and 75-100%; ii) histopathological assessment: -Ve, weak (+), moderate (++), and strong (+++); iii) re-pigmentation of body sites: face, trunk, extremities, and acral areas; iv) adverse events: pain and itching. The quality of evidence for each outcome was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

Figure 1.

Study flow diagram.

Figure 2.

Risk of bias graph.

Figure 3.

Risk of bias summary.

Risk of bias assessment

Two reviewers independently and in duplicate assessed the risk of bias for the eligible RCTs using the revised Cochrane Risk of Bias tool. All three included RCTs were judged to have an overall low risk of bias, as illustrated in Figures 2 and 3. To evaluate the potential for publication bias, we planned a visual inspection of the funnel plot based on RR and standard errors, as recommended by the Cochrane Handbook for Systematic Reviews of Interventions. However, since fewer than 10 studies were included in the meta-analysis, it was not feasible to perform this assessment.

Results

Figure 1 shows the systematic search and study selection in the present review. The initial search yielded 14 articles, of which six duplicates were excluded. Eventually, only three RCTs were deemed eligible, and all were included in the meta-analysis.^8-10

Trial characteristics

The three articles included 148 patients. Of these, 74 (50%) patients received Mn combined with tacrolimus, and 74 (50%) patients received tacrolimus monotherapy. The ages of the patients in both groups ranged from 12 years to 60 years. The detailed characteristics are shown in Table 1.

Table 1.

Characteristics of the included studies.

RCTs, randomized control trials; Mn, microneedling; NR, nor recorded.

5-grade re-pigmentation scale or Physician’s Global Assessment

The three RCTs (148 analyzed participants) contributed to the main analysis.^8-10 No significant difference was noted between Mn combined with tacrolimus and tacrolimus monotherapy in PGA (RR=0.93, 95% CI: 0.53-1.62, p=0.79, I²=68%). The heterogeneity was 68%, indicating considerable variability in the data, which was mostly attributed to the Ebrahim et al. trial.⁸ Subgroup analysis revealed that applying Mn with tacrolimus showed a significant re-pigmentation rate in the vitiligo sites compared to applying tacrolimus monotherapy, as it showed improvement with a rate of 51% to 100% from the baseline (RR=1.92, 95% CI: 1.32-2.80, p=0.0006, I²=1%). On the other hand, no significant difference was observed between Mn with tacrolimus and tacrolimus monotherapy in individuals who had only a re-pigmentation rate of 1% to 50% (RR=1.11, 95% CI: 0.52-2.36.1, p=0.78, I²=36%) and in patients who had poor and no re-pigmentation (RR=0.31, 95% CI: 0.09-1.10, p=0.07, I²=66%). The re-pigmentation rate was taken after six months of follow-up (Table 2). The GRADE certainty of evidence was found to be rated as moderate, 5-grade re-pigmentation scale (Table 3).

Histopathological assessment

Two RCTs (108 analyzed participants) contributed to the analysis of histopathological assessment.^8,9 Both Mn combined with tacrolimus and tacrolimus monotherapy showed similar histopathology (RR=0.90, 95% CI: 0.47-1.75, p= 0.76, I²=67%). Subgroup analysis revealed that treatment with Mn combined with tacrolimus was statistically significantly associated with higher strongly positive stained cells, indicating the presence of more melanoblasts compared to tacrolimus monotherapy (RR=2.11, 95% CI: 1.31-3.93, p<0.002, I²=0%). Both Mn combined with tacrolimus and tacrolimus monotherapy showed no significant difference in individuals whose biopsies showed moderately positive stained cells (RR=1.67, 95% CI: 0.65-4.28, p<0.29, I²=0%) and in weakly positive stained cells (RR=0.54, 95% CI: 0.23-1.26, p<0.15, I²=0%). Finally, the absence of melanoblasts and stained cells had a significantly higher rate in the group that received tacrolimus monotherapy (RR=0.26, 95% CI: 0.11-0.64, p<0.004, I²=0%) (Table 4). The GRADE certainty of evidence was found to be rated as moderate for histopathological assessment (Table 3).

Re-pigmentation of body sites

Two RCTs (108 analyzed participants) reported data on the re-pigmentation of body sites.^8,9 Overall, administration of Mn combined with tacrolimus showed superior re-pigmentation rates when compared to tacrolimus monotherapy in all assessed body sites with overall low heterogeneity (RR=2.02, 95% CI: 1.51-2.70, p<0.00004, I²=24%). Subgroup analysis also showed that Mn combined with tacrolimus had statistically significant higher re-pigmentation rates compared to tacrolimus monotherapy in the face (RR=1.54, 95% CI: 1.15-2.05, p=0.003, I²=0%), trunk (RR=2.11, 95% CI: 1.27-3.51, p=0.004, I²=0%), extremities (RR=2.78, 95% CI: 1.63-4.74, p=0.0002, I²=0%), and acral areas (RR=12.45, 95% CI: 1.67-92.64, p=0.01, I²=0%) (Table 5). The GRADE certainty of evidence was found to be rated as moderate for re-pigmentation of body sites (Table 3).

Adverse events

Two RCTs (108 analyzed participants) reported this outcome.^8,9 Both studies showed that combining Mn with tacrolimus and using tacrolimus alone are tolerable, and no major adverse events like scarring or koebnerization were reported (OR=1.72, 95% CI: 0.10-29.36, p=0.71, I²=82%). Subgroup analysis showed that combined Mn with tacrolimus was significantly associated with more painful treatment (OR=28.58, 95% CI: 3.66-223.6, p=0.001, I²=0%); however, the pain was reported to be mild in both studies. Tacrolimus monotherapy was more associated with a mild burning sensation or itchiness, but no significant difference was noted (OR=0.17, 95% CI: 0.01-2.17, p=0.17, I²=64%) (Table 6). The GRADE certainty of evidence was found to be rated as low for adverse events (Table 3).

Table 2.

Forest plot of 5-grade re-pigmentation scale or Physician’s Global Assessment.

Mn, microneedling; CI, confidence interval; IV, inverse variance.

Discussion

This comparative systematic review and meta-analysis compared the efficacy and safety of Mn combined with tacrolimus versus tacrolimus monotherapy for treating localized and stable non-segmental vitiligo. The pooled effect estimate showed a statistically significant higher re-pigmentation rate in all assessed body areas in favor of treatment with Mn combined with tacrolimus. Nonetheless, no significant difference was found between Mn combined with tacrolimus and tacrolimus monotherapy with respect to the 5-grade re-pigmentation scale and histopathological assessment. In terms of adverse events, both treatments were safe to use and tolerable, with no major adverse events reported.

The finding of our review showed that 44.6% of those who received Mn combined with tacrolimus achieved an excellent re-pigmentation rate (75-100%) on PGA. Our finding is inconsistent with previous studies: Korobko et al.¹⁵ reported an excellent re-pigmentation rate of only 4.5%; Mina et al.¹⁶ of 16%; and Ibrahim et al.¹⁷ of 32%. This variation could be attributed to several factors, such as the difference in the dose of the treatment. Mina et al. and Ibrahim et al. have only used the lowest concentration (0.03%) of tacrolimus, whereas the concentration used in two of our studies was 0.1%. Also, Korobko et al. trial recorded the response in a three-month follow-up, while in our study, the response was measured after six months. Even though our research showed that there is no significant difference in achieving a 1-50% re-pigmentation rate on PGA between combined Mn with tacrolimus (25.67%) versus tacrolimus monotherapy (22.9%), the failure rate in inducing re-pigmentation was 16.2% and 43.24% respectively, which highlights the importance of adopting a multimodal approach when treating vitiligo. In addition, histopathological assessment is another assessment tool that has offered an objective method to evaluate the re-pigmentation rate. In our review, more than half of the patients who received Mn with tacrolimus (59.25%) had very strongly positive (+++) results, which was consistent with other studies.^16,17

Generally, both Mn with tacrolimus and tacrolimus monotherapy are well-tolerated and demonstrate an acceptable safety profile. No major adverse events, such as scarring or koebnerization, were reported. Subgroup analysis showed that combined Mn with tacrolimus was significantly associated with more painful treatment than tacrolimus monotherapy; however, most of the reported adverse events are rated mild in severity, with no discontinuation throughout the treatment’s course. Likewise, four trials showed that both Mn and tacrolimus had no serious adverse effects, and permanent discontinuation has never occurred.^18-21 A mild transient burning sensation was reported after applying tacrolimus ointment to the perioral area and eyelids. Also, a vasodilation reaction after applying tacrolimus on the face was associated with patients who ingested variable and even small amounts of alcohol during the treatment course, and avoidance of such a reaction was achieved by discontinuing alcohol intake.¹⁸ Perioral dermatitis was reported only in one patient after tacrolimus usage. Moreover, the application of tacrolimus could be limited to small lesion areas, as some patients expressed their dissatisfaction with the greasy texture of the ointment and the difficulty of applying it in hair-covered areas.¹⁹ Finally, the usage of tacrolimus after ultraviolet B (UVB) plays a role in preventing phototherapy-induced erythema by inhibiting the early inflammation process.²⁰

Mn has offered both a viable option for multi-modality treatment and a good alternative to surgical grafting for stable, localized, and refractory vitiligo lesions.^22,23 The Mn mechanism of action could rely on trauma-induced micro-inflammation, which was discussed earlier and resembles the normal wound healing process. Other hypotheses suggested that Mn also works by causing melanocytic autoinoculation, as the mechanical trauma will stimulate melanocyte migration from the surrounding pigmented areas.⁸ In addition, a mechanical migration of melanocytes from the pigmented area is possible, as melanocytes can physically move with the needle; therefore, they can assist the re-pigmentation process by providing reservoirs for melanogenesis.²¹ The effectiveness of combining Mn with a topical treatment like tacrolimus may stem from the inflammatory response triggered by this combination. This response can lead to a multicellular infiltration that may counteract the effects of melanocyte-toxic T cells. Furthermore, this immunomodulation can facilitate the establishment of migrating melanocytes.²¹

Table 3.

Grading of recommendations assessment, development, and evaluation (GRADE) evidence profile.

CI, confidence interval; RCT, randomized controlled trial; RR, risk ratio; OR, odds ratio; explanations: *small sample size, **each subgroup favors a different arm.

Table 4.

Forest plot of histopathological assessment.

Mn, microneedling; -Ve, negative; CI, confidence interval; IV, inverse variance.

Table 5.

Forest plot of re-pigmentation of body sites.

Mn, microneedling; CI, confidence interval; IV, inverse variance.

Table 6.

Forest plot of re-pigmentation of body sites.

Mn, microneedling; CI, confidence interval; IV, inverse variance.

Limitations

We acknowledge that our review has some limitations. First, the number of included studies is low as a result of the novelty of the used technique. Second, the sample size provided by the included RCTs is relatively low, which limited our conclusions.

Conclusions

Microneedling is one of the most innovative modalities to treat localized and stable nonsegmental vitiligo. This study revealed that combining Mn with tacrolimus has significantly higher re-pigmentation rates in all assessed body areas when compared to tacrolimus monotherapy. Nevertheless, no significant difference was found between Mn combined with tacrolimus and tacrolimus monotherapy with respect to the 5-grade re-pigmentation scale and histopathological assessment. No major adverse events were reported, and discontinuation through the treatment course has never occurred, suggesting that Mn combined with tacrolimus is a safe and well-tolerated therapeutic alternative. Further well-designed studies with a larger sample and longer follow-up periods are required to examine the stability of the re-pigmented area and to assess additional outcomes, such as the needed number of sessions and the regimen with the best response.

Availability of data and materials

All data underlying the findings are fully available.