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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 .