Psoriasis in Latvia from year 2015 till 2020, epidemiology, systemic therapy tendencies

Psoriasis is chronic inflammatory skin disease mediated by the immune system, which affects the skin, nails, and joints. A characteristic feature of psoriasis vulgaris is an erythematous, scaling plaque on the scalp, lower back and extensor surface of elbows and knees. The reported prevalence of psoriasis worldwide ranges between 0.09% and 11.43%, an incidence of psoriasis of 2.30–3.21 cases per 1000 person-years [Michalek et al., 2016]. In Latvia the occurrence of the disease has not been previously investigated. Data was obtained from the Latvia National Health Service (NHS). We analysed data for psoriasis patients (ICD code L40) who during the period from year 2015 till the end of September 2020 attended doctors, working within NHS system. We report incidence, the spread of the disease by age group, gender, and national distribution. The prescribed psoriasis treatment was analysed as well. Information about population annual data was retrieved from the Central Statistical Bureau of Latvia. The annual psoriasis incidence rate in Latvia was constant throughout the analysed period and was 2.1-2.2 cases per 1000 person-years. We observed significant increase of psoriasis incidence in comparison to period from year 2005 till 2014, when incidence was 0.6 – 0.8 cases per 1000 person-years. Incidence of psoriasis appears to be slightly more prevalent among women than among men. The largest number of people diagnosed with psoriasis annually was in Riga, followed by Daugavpils, Liepaja, Jelgava and Ventspils. Use of systemic therapy increased every year since year 2015, especially starting from year 2018. Since year 2018, when biologic medications in Latvia were included into reimbursed medicines list for moderate to severe psoriasis, prescription of systemic conventional medications has significantly increased.