Introduction Psoriasis is a common, chronic inflammatory skin disease. People with psoriasis are at risk of developing liver fibrosis due to increased rates of NAFLD, alcohol use and methotrexate exposure. It is unclear which patients should be screened for fibrosis and the best method of screening. The aims of this single centre, prospective cohort study were to (1) identify the proportion of patients with steatosis and fibrosis,(2) Identify important prognostic factors for fibrosis,(3) Evaluate non-invasive tests for fibrosis.
Method Participants completed a questionnaire, psoriasis severity score, anthropometric indices and fasting blood draw for lipids, HOMA-IR,liver function tests and a panel of non-invasive markers: P3NP, FIB-4, ELF (Enhanced Liver Fibrosis) and Fibrotest. Steatosis was assessed by ultrasound. Diagnosis of fibrosis was made by liver stiffness measurement (LSM) in kilopascals (kPa) using transient elastography (TE). Those with LSM >7 kPa were referred to hepatology +/- liver biopsy. Diagnostic accuracy of bloods and clinical measures were compared to TE and biopsy.
Results 400 adults were recruited 2012–2015. Means (S.D) of enrolment parameters were: age (years): 49.5±13, 27% female, body mass index: 29.2±7, waist (cm): 102%±16. 48% had steatosis, 20% liver fibrosis (LSM ≥7 kPa); 14% had advanced fibrosis (LSM ≥8.7 kPa).
Prognostic factors significantly associated with fibrosis on univariate analysis included age, BMI, waist, metabolic syndrome, steatosis and HOMA-IR (all p≤0.01). Sex, methotrexate duration, psoriasis duration and alcohol were not significantly associated. Multivariate analysis identified waist measurement, HOMA-IR and AST as the best performing joint model of fibrosis (R2=0.379), determined by stepwise variable selection.
47 participants had a liver biopsy. 39 biopsies were available for blinded grading according to NASH-CRN. Transient elastography was the best performing non-invasive test using biopsy as a reference standard (AUC 0.81 for advanced fibrosis).
Using elastography as the reference standard, for both fibrosis and advanced fibrosis HOMA-IR and waist measurements provided the strongest predictive measures with all AUCs>0.78. For fibrosis ELF was the best performing blood test: AUC 0.75 (CI: 0.679–0.828). For advanced fibrosis AST was the best performing blood test: AUC 0.75 (CI: 0.677–0.824).
Conclusion A significant proportion of our cohort has steatosis and fibrosis. Metabolic parameters were the most important prognostic factors emphasising the risk conferred by abdominal obesity. Waist measurement, an easy test to perform, was superior to non-invasive bloods as a marker of fibrosis and advanced fibrosis. Future work will focus on the development of an algorithm to screen patients with severe psoriasis for fibrosis.
Disclosure of Interest None Declared
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