Phototherapy for Psoriasis – Outdated or Underused?

A. Tanew; H.W. Lim


The British Journal of Dermatology. 2018;179(5):1019-1020. 

Complete clearance of severe psoriasis with photochemotherapy (psoralen–ultraviolet A) was a therapeutic breakthrough in the 1970s. The prominent role of phototherapies for the management of a wide range of dermatological disorders was further promoted by the introduction of narrowband ultraviolet B (NB–UVB) phototherapy in the late 1980s and of ultraviolet A1 phototherapy in the early 1990s. Up to the present, a wealth of data has accumulated from clinical and experimental studies in addition to abundant empirical use on the efficacy, mode of action and, in particular, long–term safety of phototherapies.[1–3]

The value of dermatological treatments is determined by their ability to improve or clear a given disease, by their short– and long–term safety, practicability, accessibility and their cost–effectiveness. Phototherapies have been shown to be highly effective for psoriasis[4] and numerous other skin diseases including eczema, parapsoriasis, mycosis fungoides, lichen planus, vitiligo, various pruritic conditions and photodermatoses. Phototherapies are commonly combined with other treatments to provide for an accelerated or enhanced clinical response.[5,6]

As a result of their use over decades, the long–term safety and side–effect profiles of phototherapies are well established. Photoageing and photocarcinogenesis are correlated with the cumulative ultraviolet exposure dose and are mostly associated with psoralen–ultraviolet A photochemotherapy.[7] In fact, the largest study to date on NB–UVB phototherapy did not show any association with photocarcinogesis.[8] Limitations of phototherapies are also well recognized, namely, time and effort needed by the patient to attend the sessions and the availability of phototherapy centres. Home therapy would obviate these obstacles but is associated with the need to lease or buy a phototherapy unit in addition to training in self–administered NB–UVB therapy.[9]

As to the actual costs of phototherapies, only sparse data have been available so far. The study by Boswell et al. published in this issue of the BJD addresses this important issue by assessing direct and indirect costs incurred for NB–UVB treatment of psoriasis by a healthcare provider (NHS Tayside, Scotland).[10] Furthermore, phototherapy–related cost–savings because of the reduced need for topical psoriasis treatment were also analysed.[10] The authors calculated a cost of £257 for a NB–UVB treatment course (averaging 30 NB–UVB sessions and equating to £8·50 per session) and a saving of £53 in topical treatment. With a net average cost of £204 per treatment course, NB–UVB is a highly cost–effective treatment option for psoriasis. Although the calculated costs may vary somewhat in other healthcare systems, this study does provide important information on the cost–effectiveness of NB–UVB phototherapy for psoriasis.

How do these findings apply to the place of NB–UVB in the algorithm of modern psoriasis management? The development and availability of highly effective biological and new small–molecule treatments for psoriasis have resulted in a steady decline in the use of phototherapy for this indication.[11] It is, however, important to appreciate that these new treatments and phototherapy are different in several important respects.

Biologics and small molecules are administered continuously with the aim to induce maintained remission, whereas phototherapy is performed on demand in cyclic courses. The latter implies relapses but allows for extended treatment– and cost–free periods. Interestingly, a secondary loss of response that not infrequently occurs after prolonged treatment with systemic agents including biologics does not seem to occur with phototherapy. As opposed to phototherapy, treatment with biologics or new small molecules is much less time–consuming for patients, and these agents are also effective for psoriatic arthritis. The precautions with using these new treatments are well known and include inflammatory bowel disease, immunosuppression, chronic infection, history of internal malignancy and history of depression. There is also a lack of robust data on the risks associated with continuous long–term use of biologics or new small molecules, whereas the long–term hazards of phototherapy are well delineated. Last, but not least, in sharp contrast to NB–UVB phototherapy, biologics and new small molecules are very expensive therapeutic modalities and responsible for a large portion of the medical cost of psoriasis.[12] Therefore, the findings of Boswell et al. highlight the substantial cost–saving potential that may arise from the diligent use of NB–UVB phototherapy.

The availability of new, effective, yet costly, therapeutic agents for psoriasis provide all of us with excellent treatment options for our patients. However, in this era of ever increasing costs of health care, NB–UVB phototherapy stands out as a time–honoured, highly versatile and cost–effective therapeutic tool that must be maintained as an integral part of our therapeutic armamentarium.[13]