The 2022 British guidelines for narrowband ultraviolet B phototherapy: an absolute necessity for anyone administering or prescribing phototherapy.

The British Association of Dermatologists (BAD) and British Photodermatology Group (BPG) guidelines have been developed by a group of 10 highly experienced dermatologists in the phototherapeutic field, supported by a medical physicist, a phototherapy nurse, three patient representatives and a professional technical team. The guidelines have been established using the BAD’s recommended methodology. Both the BAD and BPG have an excellent track record of publishing phototherapy guidelines and this is certainly the case with these guidelines, which can be considered an absolute necessity for anyone administering or prescribing phototherapy. The guidelines provide detailed insights and highlight recommendations for practical use of narrowband ultraviolet B (NB‐UVB) phototherapy both in the clinic and at home.

These recommendations were developed on the basis of evidence from systematic reviews of the literature pertaining to the clinical questions identified, after internal discussion. Recommendations and outcome measures of importance to patients were set and ranked according to the GRADE methodology (i.e. grading of recommendations assessment, development and evaluation). In total 38 phototherapeutic recommendations derived from literature review and consensus are provided for many diseases, including psoriasis, eczema, vitiligo, palmoplantar dermatoses, lichen planus, morphoea (localized scleroderma), mycosis fungoides, pityriasis lichenoides, progressive macular hypomelanosis, subacute and nodular prurigo, idiopathic or secondary pruritus, and chronic urticaria, as well as photodermatoses, such as polymorphic light eruption, solar urticaria, actinic prurigo, photoaggravated eczema and hydroa vacciniforme.

These guidelines offer many specific references, and an impressive appendix of 580 pages with an additional 464 references. They present information on light sources and dosimetry, protocols for treatment delivery, an evidence‐based analysis of the efficacy of combining therapies with various topical or systemic agents, contraindications, and safety and adverse effects. One special feature is recommendations regarding the circumstances under which treatments can be administered in pregnant or breastfeeding patients and children. In addition, the authors provide a list of key future research recommendations, such as patient characteristics that predict their response to NB‐UVB, a re‐evaluation of NB‐UVB vs. psoralen plus ultraviolet A for the treatment of certain diseases, and long‐term treatment follow‐up and safety evaluations with regard to potential carcinogenic properties. However, the authors also present many diseases for which NB‐UVB has been administered, but where evidence is still insufficient to support any recommendations, presented in alphabetical order from acne to subcorneal pustular dermatosis.

Finally, the guidelines outline the relatively low costs of NB‐UVB as a unique intermittent treatment. At approximately £300–400 per treatment course in the UK, these are on the order of 10–30 times lower than the yearly treatment costs of a biologic agent (which needs to be administered continuously), depending on the specific drug and country. It is important to note that such agents have only been approved for two diseases thus far, namely psoriasis and atopic dermatitis, whereas phototherapy continues to be a mainstay for the many other diseases listed above.

We have recently elucidated the complex therapeutic mechanisms of phototherapy (with its proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary and pro‐prebiotic key components), which, unlike biologics, does not increase the risk of antidrug antibody formation and the resulting potential loss of efficacy after repetitive exposure. Balancing the immune response with phototherapy by suppressing the interleukin‐23–T helper 17 axis and inducing regulatory T cells may be beneficial not only for the treatment of many inflammatory skin diseases and conditions with immunological disturbance, but also for the treatment of mycosis fungoides, a cutaneous T‐cell lymphoma with a heavy inflammatory milieu. Such balancing may also be helpful for treating diseases on the systemic level, such as by suppressing the imbalanced immune response and reducing mortality in conditions such as severe COVID infection, as has recently been suggested in a pilot study. Indeed, the therapeutic mechanisms of NB‐UVB (e.g. how the interaction of UV with the skin’s microbiome affects immune regulation) can be further scrutinized, asking pertinent research questions related to this topic to keep the guidelines vibrant and to further develop, improve and support treatment in the future.

Author contributions

Peter Wolf: Conceptualization (equal); writing – original draft (equal); writing – review and editing (equal).