Psoralen–ultraviolet A vs. narrow-band ultraviolet B phototherapy for the treatment of vitiligo

Authors


*Corresponding author, Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education & Research, Chandigarh – 160 012, India, fax +91-172-2224819; E-mail: dprs@satyam.net.in

Abstract

Background  Although many treatment modalities have been tried for the treatment of vitiligo, none is uniformly effective. Psoralen phototherapy (psoralen ultraviolet A (PUVA)) is established as efficacious treatment for vitiligo. Recently, narrow-band UVB (NBUVB) has been reported to be an effective and safe therapeutic option in patients with vitiligo.

Objective  To compare the efficacy of PUVA and NBUVB in the treatment of vitiligo.

Design and setting  Retrospective analysis of 69 patients with vitiligo who were treated either with PUVA or NBUVB at the pigmentary clinic of the Dermatology Department of the Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Outcome measures  The following variables were compared between the two groups of patients: repigmentation status, number of treatments for marked to complete repigmentation in existing lesions, appearance of new lesions or increase in size of existing lesions, adverse effect of therapy, stability of repigmentation and colour match.

Results  In PUVA-treated group, 9 patients showed marked to complete repigmentation (23.6%) and 14 patients showed moderate improvement (36.8%), whereas in NBUVB-treated group, 13 patients showed marked to complete repigmentation (41.9%) and 10 patients showed moderate improvement (32.2%). A statistically significantly better stability and colour match of repigmentation with surrounding skin was seen in NBUVB-treated patients.

Conclusion  We showed that NBUVB is more effective than PUVA and repigmentation induced with NBUVB is statistically significantly more stable.

Introduction

Vitiligo is an acquired depigmentary disorder of great cosmetic importance characterized by loss of melanocytes from the epidermis. It affects people of all races and the prevalence varies from 0.1% to 4% in different parts of the world.1–3 Despite continued progress towards an elucidation of the genetic and immunopathological pathways in vitiligo, a definitive cure remains elusive.

Although psoralen phototherapy (psoralen ultraviolet A (PUVA)) is still the mainstay of therapy in vitiligo, adverse effects like nausea, phototoxic reactions, risk of cataract as well as long-term carcinogenic risk limit its use. A recent 10-year retrospective study showed that PUVA is only moderately effective in widespread vitiligo.4 Narrow-band ultraviolet B (NBUVB) is a new addition to the armamentarium of therapies for vitiligo.5,6 Patients prefer it because they do not have to wear protective eyewear, take tablets, or experience adverse effects such as nausea. The clinical experience with narrow-band UVB in vitiligo is limited and no comparative trial of PUVA and narrow-band UVB in the treatment of vitiligo has been reported yet.

We performed a retrospective analysis of patients with vitiligo who were treated either with PUVA or NBUVB at our pigmentary clinic to compare these in terms of efficacy, time to repigment, stability of repigmentation and adverse effects to help decide if one had an advantage in the treatment of vitiligo.

Materials and methods

The study was a retrospective analysis of 69 patients with vitiligo who were treated either with PUVA or NBUVB at the pigmentary clinic of the Dermatology Department of the Postgraduate Institute of Medical Education and Research, Chandigarh, India. These patients were treated as per protocol of our clinic. A high degree of uniformity was achieved in data collection as it was retrieved from properly filled vitiligo files and phototherapy treatment files. The basic data obtained included age, sex, duration of the disease, family history and sites of involvement (Table 1).

Table 1.  Demographic profile of patients
Total patients N = 63On PUVA (N = 38)On NBUVB (N = 31)
Age
 Mean24.8 years22.6 years
 Range15–56 years14–49 years
Sex
 Female2118
 Male1713
Family history of vitiligo11 9
Duration of disease
 <1 year0503
 1–3 years2319
 > 3 years10 9
Disease extent
 Average body surface area23.5%26%
 Average cumulative dose (J/cm2)UVA-980UVB-118

Study groups

PUVA. Oral 8-methoxypsoralen at a dose of 0.6 mg/kg were taken 2 h before UVA exposure. Patients were started on a dose of 2.5 J/cm2. PUVA was administered three times a week on nonconsecutive days. Incremental increases of the previous dose were made at each visit depending upon the response.

NBUVB. NBUVB (Philips TL-01) phototherapy was administered three times a week on nonconsecutive days. Phototesting was not performed and a standard initial dose of 280 mj/cm2 was started in all patients. Depending upon response, the irradiation dose was increased by 20%.

The treatment data for each patient included: repigmentation grading (mild, moderate, marked and complete), total number of treatments for marked to complete repigmentation in existing lesions, cumulative dose, appearance of new lesions or increase in size of existing lesions, stability of repigmentation, colour match with surrounding skin and adverse effect of therapy.

Stability (ability to retain pigment) of the repigmentation in the representative lesion was assessed at 6 months after stopping the therapy.

Statistical analysis

The two treatment groups were compared. Statistical analysis was performed using Wilcoxon and one-way analysis of variance option This corresponds to the nonparametric two-sample Wilcoxon and two-sample t-tests.

Results

Of 69 patients (39 women and 30 men) analysed, 38 were on PUVA and 31 patients were on NBUVB therapy. Both groups were well matched for age, sex, extent of body involvement, etc.

In the PUVA-treated group, 9 patients showed marked to complete repigmentation (23.6%), 14 patients showed moderate improvement (36.8%) and 3 patients continued to worsen (7%). The remaining patients showed no to mild repigmentation.

In NBUVB-treated group, 13 patients showed marked to complete repigmentation (41.9%), 10 patients showed moderate improvement (32.2%) and none of the patients showed worsening. The remaining patients showed no to mild repigmentation. There was statistically significant difference on comparing marked to complete repigmentation in both groups.

The face and neck showed the best repigmentaion response, whereas response was moderate in lesions overlying trunk and proximal extremities in both groups. Areas with lower density/no hair such as the hands, feet and bony prominences hardly achieved mild or no repigmentation.

A similar percentage of patients in each group (PUVA, 79%, NBUVB 72%) developed grade 1 erythema, showing that the regimens were equally erythemogenic. Pruritus occurred equally in both groups, but only patients in the PUVA group developed nausea. No other significant adverse effects of treatment were noted.

Colour match of the treated area to the surrounding normal skin was found better in NBUVB-treated patients (86%) as compared with the PUVA group (35%) which was statistically significant.

The data of only 58 patients were available regarding stability of repigmentation. Eighteen of 30 patients (60%) had stable repigmentation after 1 year of stopping treatment that were on PUVA, whereas 22 of 28 patients (78.5%) showed stability of repigmentation in NBUVB-treated group.

Discussion

In 1981, Parrish and Jaenicke found that 311-nm wavelength of UVB radiation was effective for the treatment of psoriasis.7 This gave impetus for developing the TL-01 fluorescent bulb, the narrow-band UVB source. This form of phototherapy was developed to remove the shorter more erythemogenic wavelengths and to use wavelengths between 305 and 311 nm, which are most efficient in clearing psoriasis.

Westerhof et al.8 in 1997 first reported the use of narrow-band UVB phototherapy for the treatment of vitiligo. In their comparative study of twice-weekly topical PUVA to twice-weekly narrow-band UVB phototherapy, 67% of the patients undergoing narrow-band UVB phototherapy showed repigmentation compared with 46% of the patients receiving topical PUVA after 4 months of therapy. Authors concluded that NBUVB was slightly but not significantly more effective than topical PUVA.

In a recent meta-analysis of non-surgical therapies in generalized vitiligo by Njoo et al.,9 higher success rates were observed with narrow-band UVB (63%) than oral PUVA (51%).

The mechanism of action of narrow-band UVB phototherapy has not been completely understood. Similar to PUVA therapy, narrow-band UVB may exert its effects on vitiligo in a two-step process, both of which may occur simultaneously. First being the stabilization of the depigmenting process, and second, the stimulation of residual follicular melanocytes.10,11

In conclusion, our findings support the previous observations that narrow-band UVB is an effective and well-tolerated treatment option for patients with vitiligo. We showed that NBUVB is more effective than PUVA and repigmentation induced with NBUVB is statistically significantly more stable than that of PUVA. Distinct advantages over PUVA include lack of psoralen-related side-effects and its precautions, cosmetically better colour match and stability of repigmentation. Although long-term risk of carcinogenesis is not exactly known at present, it is speculative to be less than that of PUVA.

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