title: Half-side comparison of erythemogenic versus suberythemogenic UVA doses in oral photochemotherapy of psoriasis.
abstract: BACKGROUND
  Early American and European multicenter trials on the efficacy of photochemotherapy (PUVA) for psoriasis have clearly shown that the treatment protocol has a crucial impact on the cumulative UVA dose required for clearing patients. Most, if not all, treatment protocols rely on the PUVA-induced erythema as a guideline for UVA dosimetry.
  
  
  OBJECTIVE
  Our aim was to investigate whether phototoxic erythema is integral to an optimized PUVA protocol or reflects an unnecessary overexposure of patients.
  
  
  METHODS
  A standard high-dose UVA regimen using minimal phototoxic doses (MPD) was compared against two different low-dose regimens. To this purpose a bilateral comparison study was performed on 31 patients and divided in two parts. In the first trial on 14 patients, half of each patient's body was irradiated at each visit with 1 MPD, whereas the other half received only two thirds of the MPD. In the second trial on 17 patients treatment with 1 MPD was compared against treatment with one half of the MPD.
  
  
  RESULTS
  A total of 27 patients (12 patients in the first trial, 15 patients in the second trial) completed the study. In both trials the suberythemogenic doses were therapeutically as effective as the minimal phototoxic doses.
  
  
  CONCLUSIONS
  We conclude that PUVA-induced erythema is not a prerequisite for effective psoriasis treatment and that a low-dose UVA regimen is a promising approach to increase the short- and long-term safety of photochemotherapy.
authors.affiliation: Division of Special and Environmental Dermatology, Department of Dermatology, University of Vienna Medical School, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Tanew
authors.forename: B
authors.initials: B
authors.lastname: Ortel
authors.forename: H
authors.initials: H
authors.lastname: Hönigsmann
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002908:Chronic Disease; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000209:etiology*; D006801:Humans; D008875:Middle Aged; D010778:Photochemotherapy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D011565:Psoriasis / Q000150:complications / Q000188:drug therapy*; D011879:Radiotherapy Dosage; D014467:Ultraviolet Therapy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods