The Higher Proportion of Men with Psoriasis Treated with Biologics May Be Explained by More Severe Disease in Men

Moderate to severe psoriasis, once regarded as merely a skin disease, is today seen as an inflammatory systemic disease. The sex ratio of the prevalence of psoriasis is balanced. In recent years several reports have documented that men receive more systemic or UV treatment than women, and different hypotheses were made. In PsoReg, the national registry for systemic treatment of psoriasis in Sweden, we have, like other European registries, observed a predominance of men (59%), especially of men treated with biologics (63%). Biologics are a relatively new group of very effective but high-priced drugs. The objective of this study was to analyse if women are discriminated by not having the same access to the high-priced biologics. Design: Population based cohort study using data from a nationwide quality register of psoriasis patients. Population: 2294 patients with moderate to severe psoriasis receiving systemic treatment from a specialist in dermatology. Main Outcome Measures: Time to initiation of biologic treatment. A multiple Cox proportional hazard's regression was performed, with time to initiating a biologic treatment as the outcome in order to assess the independent role of the patient's sex in initiating such therapy. The psoriasis severity was defined as a time-varying variable. Results: Men had more severe psoriasis than women according to the Psoriasis Area and Severity Index (PASI), regardless of age at enrolment, and throughout the study period. The analysis in the multiple Cox regression show that age, psoriasis severity and psoriasis arthropathy were relevant factors for initiating biologic therapy, whereas sex is not. Conclusions: Although as many women as men are believed to suffer from psoriasis, men seem to be more severely affected by psoriasis. The asymmetry in allocation of biologic therapy thereby probably reflects the differing disease activity between the sexes, and is not a discrimination against women per se.