This study was a real-life study which was based on secondary data collection from the electronic or paper medical records from the Dermatology Clinics of the 14 University, Training & Research Hospitals in Turkey. Data were extracted between 02 September 2020 and 29 April 2021.

The study was a retrospective, multicenter, cohort study which was based on data collection at week 4,16 and 52 of secukinumab treatment of moderate to severe plaque psoriasis.

The observational design of the study allowed data collection about secukinumab treatment patterns and clinical and demographic characteristics of plaque psoriasis patients treated with secukinumab for 52 weeks in Turkey. The adults included in the study were treated with secukinumab for 52 weeks. The adults with no available data of PASI scores at specific time points (4, 16 and 52 weeks) and no definite description of treatment cessation were excluded. The study population consisted of adults treated with secukinumab for 52 weeks and adults dropped out before 52 weeks with available data of PASI scores at 4, 16 and 52 weeks and definite description of treatment cessation.

Retrospective data collection from secondary sources (hospital medical records) allowed time and cost saving since description of patients' characteristics, analyses of outcomes of interest and their determinants could be made in a short period of time.

The study consisted of the following periods:

• The index date was the date of initiation of secukinumab
• The study (index) period was between 18 May 2018 to 31 May 2020
• The follow-up (post-index) period was 4,16 and 52 weeks post-index

Inclusion Criteria:

• A diagnosis of psoriasis
• Age ≥ 18 years at registry baseline.
• Patients with a firm diagnosis of chronic plaque psoriasis for at least 6 months before enrollment
• Secukinumab treatment should be initiated 52 weeks before data collection date
• Moderate to severe plaque psoriasis with PASI score of ≥10 before initiating secukinumab.

Exclusion Criteria:

• Patients diagnosed with others types of psoriasis (pustular psoriasis, erythrodermic psoriasis etc) are excluded.
• Previous exposure to secukinumab or any other biologic drug directly targeting IL-17A or IL-17RA

The study population consisted of adults diagnosed as chronic plaque psoriasis with no previous exposure to secukinumab or any other biologic drug directly targeting IL-17A or IL-17RA, whose PASI score was ≥10 before initiation of secukinumab in whom secukinumab had been initiated for at least 52 weeks before data collection date.