title: A randomized, observer-blinded trial of twice vs. three times weekly narrowband ultraviolet B phototherapy for chronic plaque psoriasis.
abstract: BACKGROUND
  The optimum treatment frequency for narrowband (TL-01) ultraviolet B (NB-UVB) in psoriasis is not yet known. We have previously found three times weekly to be preferable to five times weekly treatment in our population.
  
  
  OBJECTIVE
  To compare twice weekly with three times weekly NB-UVB phototherapy in chronic plaque psoriasis.
  
  
  METHODS
  In an observer-blinded, randomized comparison, patients with chronic plaque psoriasis referred from dermatology out-patient clinics in Tayside for NB-UVB phototherapy received either twice weekly (Monday and Friday) or three times weekly (Monday, Wednesday and Friday) whole-body NB-UVB phototherapy following our standard departmental treatment protocol. Treatment was continued to clearance or until the fourth treatment after minimal residual activity (MRA) was first documented. Number of days in treatment, number of treatments, total dose and time to relapse were recorded.
  
  
  RESULTS
  In total, 113 patients were recruited, skin phototypes I-III: 58 in the twice weekly and 55 in the three times weekly group. Forty patients in the twice weekly group reached clearance/MRA, as did 44 in the three times weekly group. It took 1.5 (95% confidence interval 1.3-1.7) times longer to reach clearance/MRA with twice weekly therapy, a geometric mean of 88 vs. 58 days (P < 0.0001). Small differences in numbers of treatments and total dose to reach clearance tended to favour three times weekly therapy, but these were not significant.
  
  
  CONCLUSIONS
  Three times weekly NB-UVB clears psoriasis significantly faster than twice weekly treatment, and therefore is preferable for most patients.
authors.affiliation: Photobiology Unit, Department of Dermatology, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, U.K. hcameronderm@hotmail.com
authors.forename: H
authors.initials: H
authors.lastname: Cameron
authors.forename: R S
authors.initials: RS
authors.lastname: Dawe
authors.forename: S
authors.initials: S
authors.lastname: Yule
authors.forename: J
authors.initials: J
authors.lastname: Murphy
authors.forename: S H
authors.initials: SH
authors.lastname: Ibbotson
authors.forename: J
authors.initials: J
authors.lastname: Ferguson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011565:Psoriasis / Q000532:radiotherapy*; D012720:Severity of Illness Index; D016037:Single-Blind Method; D014467:Ultraviolet Therapy / Q000379:methods*