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CLINICAL REPORT Advances in dermatology and venereology ActaDV Acta Dermato-Venereologica ActaDV
Predictive Model for Response Rate to Narrowband Ultraviolet B Phototherapy in Vitiligo: A Retrospective Cohort Study of 579 Patients
Raul CABRERA 1, Lia HOJMAN 1, 2, Francisca RECULE 1, Rodrigo SEPULVEDA 3 and Iris DELGADO 4
1
Department of Dermatology, Clinica Alemana de Santiago – Universidad del Desarrollo, 2 Immunology Disciplinary Program, Universidad de Chile School of Medicine, Universidad de Chile, 3 Medical Technology School, and 4 Department of Epidemiology, Universidad del Desarrollo – Clinica Alemana School of Medicine, Santiago, Chile
Vitiligo is an acquired depigmenting disorder. To date, there is no predictive model for its response rate to narrowband ultraviolet B( NBUVB) phototherapy. The aim of this study was to investigate the different types of response of patients with non-segmental vitiligo undergoing NBUVB 3 times a week. Many patients who were previously considered non-responders were given the opportunity to continue the treatment. Longterm maintenance of treatment and follow-up of a cohort of 579 patients enabled different subtypes of response( very rapid, rapid, average, slow and“ nonresponders”) to be described for the first time, and a predictive model of response to be constructed based on repigmentation rate in the first 48 sessions of NBUVB. Among those patients who did not respond during the first 48 sessions, a new subgroup of patients was found, termed“ very-slow” responders, who achieved a low, but significant, level of repigmentation after 96 sessions of NBUVB.
Key words: vitiligo; phototherapy; ultraviolet; narrowband UVB; predictive model.
Accepted Jan 23, 2018; Epub ahead of print Jan 24, 2018 Acta Derm Venereol 2018; 98: 416 – 420.
Corr: Raul Cabrera, Department of Dermatology, Clinica Alemana de Santiago – Universidad del Desarrollo, Av. Manquehue Norte 1410, Vitacura, Santiago, Chile. E-mail: rcabrera @ alemana. cl
Vitiligo is the most frequent cause of acquired leukoderma, and results in significant psychological and social difficulties for patients( 1). Its prevalence varies from 0.5 % to 2 %( 2). According to the Vitiligo European Task Force, the condition can be classified on clinical grounds into 3 major forms: non-segmental vitiligo( NSV), segmental vitiligo( SV) and mixed vitiligo( MV)( 3). NSV, which is the most common type, is characterized by symmetrical and bilateral white patches or scattered symmetrical macules, with a long period of evolution. SV has a unilateral, band-shape distribution, with an early age of onset and rapid stabilization( 4). The term“ mixed vitiligo”, initially proposed by Mulekar et al. in 2006( 5), has recently been included in the main classification( 3). MV shows initial segmental involvement, but in a second phase bilateral vitiligo patches usually follow( 6). There are a few types of vitiligo that do not fall into this classification. Follicular vitiligo, recently described, is a primary vitiligo of the hair, in which hair whitening precedes leukoderma( 7). Mucosal vitiligo refers to the exclusive involvement of oral or genital mucosa( 8). Trichrome vitiligo, first suggested by Fitzpatrick( 9), is the presence of vitiliginous patches with 3 colours; an achromic centre, a hypochromic border and the unaffected skin( 10). All forms have in common progressive depigmentation of the skin, hair or mucosa( 4).
Narrow-band ultraviolet B( NBUVB) phototherapy for vitiligo was first introduced in 1980, but the first specific publication concerning its use in vitiligo was published in 1997( 11); it is currently the treatment of choice for widespread forms of vitiligo due to its proven superiority to psoralen plus ultraviolet A( PUVA) and broadband UVB in terms of clinical effectiveness( 11), safety and side-effect profiles( 12 – 14). NBUVB has also been shown to be effective and well tolerated in children( 15 – 18). Its mechanism of action includes immunomodulatory effects( 19) and activation of repigmentation by proliferation, differentiation and migration of melanocyte precursors in hair follicles( 20).
There is a full body of evidence supporting the usefulness of NBUVB in treating vitiligo, both in paediatric and adult populations. However, to date, there is no predictive model for the rate of repigmentation. This study of 579 patients constructs a new predictive model for the management of patients with vitiligo undergoing NBUVB treatment.
METHODS
This retrospective cohort study included consecutive patients with SV and NSV diagnosed by physical examination, including Wood’ s light examination, who were treated with NBUVB phototherapy at Clinica Alemana de Santiago, Santiago, Chile from January 2006 until March 2015.
Exclusion criteria were: MV, history of untreated cancer, primary or secondary immunodeficiency, photodermatoses, positive antinuclear antibodies, patients without complete photographic records, and those with failure to follow-up( i. e. patients who completed fewer than 24 sessions of phototherapy) and / or patients who missed more than 4 weeks of phototherapy. The study was approved by the IRB of Clinica Alemana de Santiago – Universidad del Desarrollo.
Phototherapy was performed according to Clinica Alemana protocols, based on Morison’ s formally proposed scheme( 21) with a variable dosage according to skin type( Table I). The Houva 4 Clinical Phototherapy System( National Biological, Ohio, USA), equipped with 48 NBUVB lamps was used, with daily calibrations performed by medical technologists. Patients underwent 3 sessions per week. No topical medications were used. doi: 10.2340 / 00015555-2889 Acta Derm Venereol 2018; 98: 416 – 420
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2018 Acta Dermato-Venereologica.