Psoriasis

The study population included patients with a first diagnosis of psoriasis between 1 January 1994 and 31 December 2009, who were 20 years or older at the time of the diagnosis. A comparison group of up to 5 controls per psoriasis patient was selected. Patients from both cohorts did not have any history of CVD or diabetes before the index date (first diagnosis of psoriasis) or corresponding consulting date and, in order to capture incident not prevalent cases of psoriasis or major CV events, all patients had to have at least 2 years prior registration within their general practice before entry into the study cohort. The control group consisted of patients who never received a diagnostic code for psoriasis. Controls were matched to psoriasis patients by age, gender, and general practice. We assigned control patients the same index date as the patients with psoriasis to whom they were matched. Person-time under observation for each patient was calculated from the corresponding index date up to the end of the study, which was the earliest date of the occurrence of a major CV event (MI, ACS, unstable angina, or stroke), transfer out of the practice, death date, end of follow-up (31 December 2011) or when the practice was no longer up to research data quality standards set by CPRD. Patient consent was not required; all patient data contained in CPRD is anonymised.

Patients with psoriasis were included if they had their first diagnostic code for psoriasis during 1 January 1994–31 December 2009 and received a recognized treatment for psoriasis (emollients, topical treatment, phototherapy, systemic therapy, or biologics (CG153 Psoriasis: NICE guideline; Samarasekera and Smith, 2014)). Patients were classified as having severe psoriasis once they had received a systemic treatment (acitretin, etretinate, ciclosporin, hydroxycarbamide, methotrexate, and fumaric acid), phototherapy, or a biologic therapy (etanercept, adalimumab, infliximab, ustekinumab, and efalizumab); alternatively they were classified as mild psoriasis.