UV-B phototherapy clears psoriasis through local effects.
OBJECTIVE
To determine if UV-B phototherapy clears psoriasis through systemic effects.


METHODS
Randomized, within-subject comparison of change in psoriasis in 3 plaques in patients attending for whole-body UV-B therapy. Change in patients' psoriasis plaques covered during UV-B treatment was compared with plaques in an untreated control group.


METHODS
University hospital phototherapy unit.


METHODS
The study population comprised 17 patients with chronic plaque psoriasis treated with UV-B and 24 psoriasis control patients awaiting UV-B phototherapy.


METHODS
Treatment with a standard 3-times weekly narrowband TL-01 UV-B regimen. Three similar plaques were randomly allocated to be covered every treatment, covered for 2 of 3 weekly treatments, and exposed to local UV-B every treatment. Similar plaques were selected in control patients (awaiting but not yet started UV-B therapy). Severity of psoriasis plaques was assessed using a scaling, erythema, and induration (SEI) scoring system.


METHODS
Change in SEI score of the selected plaques over the complete treatment course for UV-B-treated patients and change over 3 weeks in SEI score of plaques covered during UV-B treatment compared with that of plaques in controls.


RESULTS
There was a significant (P<.001) difference in how much the SEI score changed in the 3 plaques in UV-B-treated patients. It fell by a mean of 7.6 for uncovered plaques compared with 3.2 for plaques covered during each UV-B exposure (95% confidence interval for difference, 3.0 to 5.8). In patients awaiting UV-B, SEI score of plaques fell by a mean of 0.4 over 3 weeks, compared with a mean fall of 1.4 for covered plaques in UV-B-treated patients (95% confidence interval for difference in means, 0.1 to 2.0).


CONCLUSIONS
If UV-B therapy has any systemic effect capable of improving psoriasis, this effect is small and unlikely to be of clinical importance. It is insufficient to alter interpretation of findings of within-subject comparative phototherapy studies. UV-B phototherapy works for chronic plaque psoriasis through local effects.
Dawe
Robert S
RS
Photobiology Unit, Department of Dermatology, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland. r.s.dawe@dundee.ac.uk
Cameron
Heather
H
Yule
Susan
S
Man
Irene
I
Ibbotson
Sally H
SH
Ferguson
James
J
D000328:Adult; D000368:Aged; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011565:Psoriasis / Q000473:pathology / Q000532:radiotherapy*; D012720:Severity of Illness Index; D012867:Skin / Q000473:pathology / Q000528:radiation effects*; D016896:Treatment Outcome; D014467:Ultraviolet Therapy; D014916:Whole-Body Irradiation