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Treatment history of patients receiving biologic therapy for psoriasis – a Danish nationwide study

Editor Psoriasis is a common skin disease affecting approximately 2–4% of the world’s population. Management of psoriasis often involves prolonged treatment with topical, systemic and biologic agents. Topical agents, that is topical corticosteroids or topical vitamin D analogues, are considered first line of treatment for psoriasis, whereas biologics are predominantly used as a last resort, often as the result of treatment failure of conventional systemic agents. However, the specific treatment algorithms may differ between patients and countries, and certain therapies may be used off-label. The objective of this study was to characterize the use of selected topical and systemic non-biologic treatments in Danish patients treated with biologic agents. In a cross-sectional design, we evaluated the topical and systemic treatment history of patients recorded in Dermbio, a nationwide registry of patients with moderate-to-severe psoriasis treated with biologics in Denmark. Since 2007, registration by dermatologists has been mandatory upon initiation or change of biologic therapy. Since 1994, the Danish Register of Medicinal Products Statistics (DRMPS) has recorded all pharmacy-dispensed prescriptions according to the Anatomical Therapeutic Chemical (ATC) classification. Treatment procedures, for example hospital-administered systemic treatments, are recorded in the Danish National Patient Register (DNPR) as treatment procedure (SKS) codes. All patients recorded in Dermbio between 2007 and 2011, alive and resident in Denmark on 31 December 2011 were included. Systemic treatments were recorded in the DNPR and the DRMPS, and data on topical treatments from the DRMPS were extracted based on ATC and SKS codes as appropriate. The study comprised a total of 1305 patients with psoriasis, predominantly male (856, 65.6%), with a mean age of 47.9 13.7 years and a mean disease duration of 21.0 12.8 years (Table 1). Most patients (1300, 99.6%) had been treated with a topical agent, with potent corticosteroids (95.5%) and vitamin D analogous (93.9%) being the most widely used therapies, followed by very potent (77.3%) and moderately potent (77.1%) corticosteroids, and some patients had received topical treatment with pimecrolimus (8%) and tacrolimus (9.4%), respectively (Fig. 1). Almost all patients (1273, 97.6%) had a history of systemic treatment, with methotrexate (94.8%) being the most frequently used systemic (non-biologic) therapy (Fig. 1). Almost all patients had been treated with methotrexate, which is likely explained by the Danish guidelines stating that initiation of biologic treatment for psoriasis should be preceded by failure of methotrexate treatment. A significant proportion of patients had a treatment history of either topical pimecrolimus or tacrolimus use; although we cannot refute that misclassification has occurred, patients recorded in Dermbio are all diagnosed by experienced dermatologists; therefore, the high usage is likely an indication of off-label use for facial psoriasis plaques, rather than due to misclassification of psoriasis, for example as eczema. We report higher frequencies of topical and systemic non-biologic treatment use compared to clinical trials and other observational studies of biologics registries. However, this may be due to use of Danish registers for information on treatment use and not patient information. Apart from the higher reported frequencies of treatments, we generally see the same treatment patterns with corticosteroids and vitamin D analogues being the most widely used topical treatments and methotrexate the most used systemic non-biologic treatment. Although the use of vitamin D analogues seems to be more prominent in our study, probably due to calcipotriene/ Table 1 Characteristics of the study population