A randomized comparison of selective broadband UVB and narrowband UVB in the treatment of psoriasis

UVB is widely used to treat psoriasis. Conventional broadband UVB lamps are less effective than narrowband UVB lamps, which have an emission peak at 311 nm. The long-term safety of narrowband UVB phototherapy is uncertain. Selective broadband UVB lamps, which have little emission < 290 nm, are also available, but have not been adequately compared to narrowband UVB lamps. We performed a randomized comparison of narrowband UVB (TL-01 lamps) and selective broadband UVB (UV6 lamps) in 100 patients with psoriasis. The median number of exposures for clearance was 28.4 for TL-01 and 30.4 for UV6 (ratio of the medians 0.93; 95% confidence interval (CI) 0.80, 1.09; P=0.39). No significant difference was found in the proportion of patients achieving clearance: TL-01 56%, UV6 40% (odds ratio for clearance with TL-01 relative to UV6 was 2.00 (95% Cl 0.87, 4.62), P=0.10). Side effects, including the development of erythema during phototherapy, were similar for the two lamp types. Risk estimates based on the human photocarcinogenesis action spectrum predict that narrowband UVB lamps will be 50% more carcinogenic for equal erythemal doses than selective broadband lamps (UV6). As these two lamp types appear to be of similar efficacy, phototherapy using a selective broadband source may be a safer option than use of narrowband UVB.