Psoriasis in Norway: A Prescription-based Registry Study of Incidence and Prevalence.

Epidemiological data on psoriasis in Norway are limited. The aim of this study was to provide objective national data on the incidence and prevalence of psoriasis. Patients registered in the Norwegian Prescription Database with a diagnostic code indicating psoriasis vulgaris on prescriptions were included. During the period 2004 to 2020, 272,725 patients received prescription for psoriasis vulgaris in Norway. During the period 2015 to 2020, 84,432 patients received prescription for psoriasis vulgaris for the first time. In 2020, 71,857 (97.7%) patients received topical, 7,197 (9.8%) conventional systemic and 2,886 (3.9%) biological medication for psoriasis vulgaris. In the period 2015 to 2020, the point prevalence of psoriasis was 3.8-4.6% and the incidence was 0.29-0.25%. Norway is divided into 4 geographical health regions. A latitudinal difference was observed between the 4 regions, highest in Northern Norway. In the incidence population, median age was 47-53 years and males comprised 46-50%. In this study of psoriasis vulgaris, prevalence in Norway was higher than in earlier reports from other countries. There was a small female predominance regarding incidence and prevalence; however, men had more prescriptions for systemic treatment. Prescriptions for psoriasis vulgaris showed a stable level, with a trend of increasing use of biological medication during the study period.