INTRODUCTION
Psoriasis is a common, chronic immune-mediated inflammatory skin disorder with potential systemic complications. Psoriasis causes significant quality of life issues, even in mild cases, and is associated with excess all-cause mortality in patients with severe disease.1-7 Current epidemiological studies have demonstrated that psoriasis affects anywhere from 0.45-4.6% of the population worldwide, and the incidence and prevalence are influenced by both ethnic and genetic factors.2,3,5,6,8
The majority of psoriatic patients are adequately controlled with topical medications, a cornerstone of psoriasis treatment. However, approximately 20% of patients have moderate-to-severe disease,3,9 classically defined as a body surface area (BSA) of > 5%, or a Psoriasis Area Severity Index (PASI) score >7-12 or a Dermatology Life Quality Index (DLQI) score >10. These patients are often unresponsive to topical treatments and therefore require more intensive options including systemic immunomodulators, biologics, and/or ultraviolet (UV)-based therapies.
Phototherapy has remained a mainstay option for patients with moderate-to-severe psoriasis due to its efficacy, cost-effectiveness, and relative lack of side effects, in particular a lack of systemic immunosuppression seen with traditional and biologic systemic therapies.9 With regards to phototherapy in the treatment for psoriasis, both UVA spectrum and UVB spectrum wavelength have been used with excellent clinical efficacy. UVA light for psoriasis is defined as wavelengths between
320 to 400 nm and is often combined with photosensitizing compounds called psoralens. The combination is termed psoralen and UVA light (PUVA).10 UVB light for psoriasis is further categorized as broadband (BB), defined as wavelengths between 280 and 320 nm, and narrowband (NB), defined as wavelengths between 311 and 313 nm. The purpose of this article is to review and compare the current evidence-based guideline recommendations for the use of phototherapy in the treatment of psoriasis.
Initial Clinical Encounter
Indications and contraindications
According to AAD, European S3, and NICE guidelines, phototherapy is indicated for patients with moderate-to-severe “extensive†plaque psoriasis that is resistant to or impractical for topical therapy.9,11,12 The AAD and NICE guidelines also include uncontrolled guttate psoriasis as an indication and define “extensive†psoriasis as a minimum body surface area of greater than 5% and 3%, respectively, or Psoriasis Area and Severity Index (PASI) score of 7-12.9,11 In addition, the AAD and NICE guidelines provide indications for phototherapy in consideration of quality-of-life. While a minimum body surface area has been traditionally used as a prerequisite to starting UV light or systemic therapy for psoriasis, a subset of patients with limited disease causing debilitating symptoms (ie palmoplantar disease) may be started on phototherapy. The significant negative effect on their quality-of-life of makes treatment with systemic therapies an appropriate approach in management.9,11
