Psoriasis in Norway: a prescription-based registry study of psoriasis-associated comorbidities

Psoriasis is an inflammatory skin disease, frequently associated with comorbidities. The aim of this study was to characterize comorbidities associated with skin psoriasis using real-world data. The study was conducted in Norway, taking advantage of the universal healthcare system with equal access to healthcare and a mandatory prescription reporting system that applies to all hospitals and clinics. The study focused on patients registered in the Norwegian Prescription Database (NorPD) who had either a diagnosis code indicating skin psoriasis alone or in combination with diagnosis codes for pre-selected comorbidities. Between 2004 and 2020, a total of 272,725 patients diagnosed with skin psoriasis were identified in NorPD, and 84,432 patients received their first prescription for skin psoriasis between 2015 and 2020. Among these, patients who received prescriptions for pre-selected comorbidities, either before or after initial prescription for psoriasis treatment, were included in the study. The most common prescriptions for patients with skin psoriasis were for primary prevention of atherosclerotic disease (22.6%), established atherosclerotic disease (19.3%), and depression (18.4%). These were closely followed by prescriptions for other comorbidities such as heart failure (16.1%), type II diabetes mellitus (9.4%), hypertension (9.4%), anxiety (7.8%), psoriatic arthritis (5.5%), acute myocardial infarction (4.2%), hypertensive cardiac disease (3.0%), ulcerative colitis (2.4%), type I diabetes mellitus (2.2%), secondary prophylaxis after myocardial infarction (1.6%), and Crohn's disease (1.0%). Patients with skin psoriasis have a high number of prescriptions not only for their psoriasis but also for many other conditions compared to reports in the literature on the general population.