Investigator‐blinded, controlled, and randomized comparative study on 1565 nm non‐ablative fractional laser versus 5% minoxidil for treatment of androgenetic alopecia

Characterized by progressive hair loss due to an excessive response to androgens, androgenetic alopecia (AGA) affects up to 50% of males and females. Minoxidil is one of approved medications for AGA but inadequate responses occur in many patients.


| INTRODUC TI ON
Androgenetic alopecia (AGA) is a common hair loss disorder which affects up to 50% of men and women. 1 Hair loss has substantially negative impacts on both psychological states and social interactions.The treatment options for AGA are limited, depending on various factors including efficacy, practicability, risks, and costs.
The current available modalities require lifelong course treatment and are associated with various side effects. 2 Particularly, for those who would not accept medicines, treatment options are very few.
Therefore, there are unmet needs for development of novel and effective hair loss interventions.Recent research shows that tissue hardness plays an important role in hair loss diseases.Chen et al reported that the vertex scalp hardness of subjects with grade 3 AGA was higher than those without AGA. 3The severity of AGA correlated with scalp hardness positively 3 and such a condition can be mitigated using energy-based modalities-fractional lasers.Fractional photothermolysis, introduced by Manstein and Anderson in 2004, is a laser technique that generates microscopic thermal injury zones (MTZs) into the skin. 4These numerous "fractional" microscopic columns are with controlled depth, width and density.Surrounded by intact epidermal and dermal tissues, each MTZ is to facilitate wound healing. 5[11][12] It has been postulated that fractionated laser acts as a wounding source, increasing blood flow, inducing expressions of cytokines and growth factors, and stimulating dermal papilla cell growth and/ or stem cell. 10,11In addition, perifollicular fibrosis has been found in AGA. 13 It has been known that collagen remodeling can be achieved after a fractional laser treatment, 14 which may be beneficial to alleviate perifollicular fibrosis.
In this study, we hypothesized that the 1565 nm NAFL could yield a therapeutic benefit for patients with AGA, providing an alternative approach to those who would not accept or are not satisfied with medicines.As this modality had not been previously evaluated, our aim in this trial was to evaluate the efficacy and safety profiles of 1565 nm NAFL, as compared with topical minoxidil in treating AGA.

| Study design
This was an evaluator-blinded, experimental, randomized, prospective controlled clinical trial with a treatment course of 10-week.

| Participants
The inclusion criteria were as follows: male patients with AGA at stage I-III determined using the modified Norwood-Hamilton classification; female patients with AGA with Ludwig classification type I or II; age 18-45 years; and capability to follow the study protocol.
The exclusion criteria were as follows: the use of scalp light or with laser treatment within 6-month; the use of topical or systemic drugs affecting hair growth within 12-month; taking oral finasteride within 18-month prior to the start of the trial; history of hair transplant; and systemic or scalp diseases that may affect hair growth.The date of first enrollment was on May 25, 2022.Written informed consent was obtained from all participants.Prospective patients with AGA were selected based on the inclusion and exclusion criteria above.

| Treatment protocol
The hair loss area was treated.Before each session of treatment, a 2 × 2 cm 2 area that did not affect the appearance of patient was randomly selected in the hair loss area where hairs were cut to 1 millimeter in length for the convenience of hair detection.Patients in the laser group were treated with 1565 nm NAFL (ResurFX mode, M22, Lumenis®, Yokneam, Israel).In order to fully fit the scalp, we removed the sapphire crystal glass sheet from the headpiece of 1565 nm NAFL as a cooling free device.The parameters of the laser therapy were: energy of 10 mJ, density of 250 spot/cm 2 , 3% overlapping treatment area, one path, with 2-week intervals for four sessions in all.For the minoxidil group, 1 mL of topical 5% minoxidil solution (National Drug approval number H20020190) was applied to the targeted hair loss area twice a day.
Photographs from both groups were taken using a digital camera (SEM; Hitachi TM3000, Hitachi, Tokyo, Japan).The point of taking dermoscopic photograph is fixed at the junction of a line connecting the apex of the ears and the midline.Dermoscopy image data were collected using a FotoFinder skin imaging system (GmbH, Germany) in the targeted area of 2 × 2 cm 2 from both groups.

| Outcome assessment
1. Photographs were obtained at the baseline, 2nd, 4th, 6th, 8th, and 10th weeks.The photographic assessment performed by 2 dermatologists blinded to the study protocol.
The patients' satisfaction scores were collected at the week of 10th with the scale system as follows: 1, satisfied; 2, somewhat satisfied; and 3, very satisfied.For safety assessment, follow-up physical examinations were performed, and related adverse events, such as pruritus, erosion, erythema, edema, irritation, dryness, seborrheic dermatitis, pain, and broken hair shafts, were monitored and recorded.

| Statistical analysis
Descriptive statistics were used to analyze the demographic dates.
The changes in hair growth indexes at the 10th week as compared with the baseline were evaluated for each group using a paired t-test.A linear mixed model analysis of variance with Bonferroni post hoc analysis was used to evaluate the significance of such changes between two groups.The agreement in scores between the two independent observers was analyzed using Cohen's kappa.With a per-protocol analysis performed for the assessment of safety intention-to-treat analysis was performed to evaluate the effects of patient demograph- A p value < 0.05 was considered statistically significant.

| RE SULTS
Thirty participants completed the entire 10-week treatment schedule.The mean age of participants was 33.5 ± 6.3 years old, with a mean duration of AGA of 8.2 ± 3.1 years.Baseline characteristics of the two groups are summarized in Table 1.

| Primary outcomes
There was no significant difference in baselines between the laser and minoxidil groups.At the 10th week, there were significant improvements in hair diameter and density from baseline in both treatment groups.Table 2 shows the analysis results of the efficacy indicators of subjects in the laser and minoxidil treatment groups.
In the 1565 nm NAFL group, there were significant increases in There was no significant difference in any other indexes before and after treatment.
We next analyzed the efficacy indicators for inter-group comparisons.The changes (∆) in the following indexes from the baseline to Week 10 in the laser treatment group were significantly greater than those in the minoxidil group: total hair number, total hair density, terminal hair number, terminal hair density, number of hair follicle units, and average hair number/number of hair follicle units (Table 2).
Trichoscopy pictures taken at baseline and Week 10 are provided in

| Secondary outcomes
The satisfaction score of the laser treatment group is significantly higher than that of the minoxidil group (Table 3).

| Adverse events
Most participants complained mild-to-moderate, but tolerable, pain during laser treatment; the symptoms were self-resolved within a few hours.Local anesthesia and analgesics were not required before or during laser treatment.None of the patients withdrew from the study owed to laser-related pain.No serious adverse events were reported for either treatment, such as scarring, infection, or worsening of hair loss.Occasionally, mild adverse events related to minoxidil treatment including temporary itchiness (two patients) TA B L E 1 Demographics and baseline characteristics of participants.β-Catenin-Lef1 signaling, leading to hair growth. 17Thus, it is reasonable to posit that the 1565 nm NAFL will act through a similar mechanism as the 1550 nm does.
Our study showed 1565 nm NAFL could be an safe and effective modality in treating AGA; it exhibited a comparative or superior clinical efficacy in some aspects of hair growth to the topical minoxidil.Patients in our cohort felt that their scalp tightness eased after 1565 nm NAFL treatment.The therapeutic effects observed in patients in this study are thought to be a combinatory result of wound stimuli induced by 1565 nm NAFL.Meanwhile, we removed the original sapphire crystal cooling contact head of 1565 nm NAFL, making the treatment handpiece completely fit to the scalp.In such a way, the laser beam could act vertically on the treating area without reducing energy.Also, patients do not need to cut hair prior to treatment.In future, addition of optimal dispersion of growth factors to the scalp will be a strategy to be tested to further improve efficacy.
A controlled and large-sample-size study will be required to validate the efficacy and elucidate the mechanism of this modality.
Additionally, FotoFinder skin imaging system was selected for the trichoscopic detection in this study.This method provides objective quantifications for numerous indexes including hair number, hair density, terminal hair count, terminal hair density, number of hair follicle units, and average hair number/number of hair follicle units.In this study, we were aware that laser treatment induced improvements in the proportion of vellus hair and the number of single hairs in hair follicles, thought these changes were statistically insignificant.This might be related to dynamic changes in scalp hair of participants.
In conclusion, both 1565 nm NAFL and 5% minoxidil medication were effective for treatment of AGA.However, 1565 nm NAFL exhibited superior clinical efficacy in some aspects of hair growth to the topical minoxidil.As a exploring research, this study demonstrates that 1565 nm NAFL can be an effective and safe modality in treating AGA.However, the study has several limitations; chief among them is the small number of patients per group.Another limitation is that the possible additive or complementary effect of topical minoxidil or nutraceuticals could not be quantified.Prospective, well-designed controlled clinical trials are needed to better understand the complementary effects of different AGA therapies.

E TH I C S S TATEM ENT
The study protocol was reviewed and approved by the ethical committee of Xijing Hospital, the Air Force Medical University.The study protocol followed the guidelines of the 1964 Helsinki declaration and its later amendments or comparable ethical standards.Informed consent was obtained from all individual participants included in the study.
TA B L E 3 Satisfaction scores of two treatment groups.
ics and treatment efficacy.Data were analyzed through the Statistical Package for Social Science (IBM SPSS, IBM Corp.) version 23.The data were presented as Mean ± SD or median (interquartile, IQR).

F I G U R E 1
Baseline and Week 10 trichoscopy pictures(A: baseline, B: Week 10) and clinical pictures (C: baseline, D: Week 10)of a participant showing the treatment with 1565 nm NAFL, with hair density climbed from 100.5/cm 2 at baseline to 124.9/cm 2 at Week 10.F I G U R E 2 Baseline and Week 10 trichoscopy pictures(A: baseline, B: Week 10) and clinical pictures(C: baseline, D: Week 10) of a female participant showing the treatment with 1565 nm NAFL, with hair count raised from 140 at baseline to 174 at Week 10 and hair density climbed from 104.1/cm 2 at baseline to 133.5/cm 2 at Week 10.| 1643 QU et al. and worsening of hair in 4 weeks (two patients) were observed and resolved spontaneously.4 | DISCUSS IONMale and female pattern hair loss (PHL) have long been long-term dermal clinical barriers for physicians to tackle; current treatment options are of limited efficacy and often result in relapse after treatment discontinuation.Side effects of drugs are often concerns for their usages, and patients continue looking for new treatments for better improvements.Phototherapy can effectively improve androgenetic alopecia, alopecia areata, and hair loss after chemotherapy and promote hair growth.15NAFLs are the most widely used phototherapy modalities with commonly available wavelengths of 1540, 1550, and 1565 nm.Compared with ablative fractional lasers, NAFLs confer many advantages, including less skin damage, shorter postoperative downtime, and lower incidence of adverse reactions.16Kim et al. 11    performed 1550 nm NAFL to treat patients with male PHL using the contralateral frontal alopecia from the same patients as control.The treatment frequency was once per 2 weeks with five sessions in total.Results showed a certain role of 1550 nm NAFL in promoting hair growth.However, one limitation for 1550 nm NAFL is that its handpiece cannot fully fit the scalp.Thus, the patient is required to cooperate with cutting hair for treatment, which cannot fully meet the clinical needs.The 1565 nm NAFL is a new type of non-ablative fractional laser with deeper penetration depth than that of the 1550 nm.Previous studies have shown that 1550 nm NAFL has a good effect in treating alopecia areata.The potential mechanisms include increase in local blood flow and stimulation of growth factors and cytokines such as Wnt-

baseline to the Week 10) p value Baseline Week 10 Baseline Week 10 Laser Minoxidil
TA B L E 2 Trichoscopy data by hair imaging system and comparative statistical analyses of efficacy indexes prior to and at the Week 10 post-treatment.a p = 0.001 as compared to the baseline in the same treatment group.b p = 0.002 as compared to the baseline in the same treatment group.