• bath-PUVA;
  • paired-comparison;
  • photochemotherapy;
  • psoriasis;
  • randomized controlled trial;
  • ultraviolet B

Summary Background  In 1991, consensus guidelines recommended psoralen plus ultraviolet A photochemotherapy (PUVA) for those requiring second-line therapy for psoriasis. Narrowband (TL-01) UVB has since become more widely available, replacing the less effective broadband sources.

Objectives To compare the efficacy of TL-01 UVB phototherapy and trimethoxypsoralen (TMP) bath-PUVA for chronic plaque psoriasis.

Participants and methods A randomized, observer-masked, intraindividually controlled, paired (half-body) study was done in the Photo(chemo)therapy Unit in Ninewells Hospital and Medical School, Dundee. The study comprised 28 patients (skin phototypes I–III) with chronic plaque psoriasis. Each patient's body halves (sagittal plane) were treated independently, one-half with TL-01 UVB, the other with bath-PUVA. Both treatments were administered according to standard, optimized regimens. Treatment was continued until clearance or minimal residual activity (MRA), or a maximum of 30 treatments. The main outcome measures were treatments and time to clearance/MRA, the proportion reaching clearance/MRA, change in psoriasis severity score (scaling, erythema and induration) and remission durations.

Results Of 18 who completed the study, all reached clearance/MRA with TL-01, but three were still not clear after 30 PUVA exposures. TL-01 achieved clearance/MRA a median of 11 (6·5–25; P = 0·001) days more quickly than PUVA, but required a median of 24·5 compared with 19 exposures [95% confidence interval (CI) for difference 1·5–5·5; P = 0·01]. Ten patients were withdrawn (four because of inadequate response of PUVA-treated halves). Analysed on an intention-to-treat basis, 21 of 28 (75%) of all participants reached clearance/MRA with TL-01 compared with 15 of 28 (54%) with PUVA (95% CI for difference 4–37%; P = 0·03). Remission durations did not differ.

Conclusions When administered according to these regimens in a skin phototype I–III population, TL-01 UVB is more efficacious than TMP bath-PUVA in the treatment of chronic plaque psoriasis.