Metabolic syndrome, non-alcoholic fatty liver disease and liver stiffness in psoriatic arthritis and psoriasis patients.

Non-alcoholic fatty liver disease (NAFLD), potentially evolving into liver fibrosis (LF), is frequent in psoriasis (PsO), but data in psoriatic arthritis (PsA) are lacking. Our study aimed to investigate the prevalence of NALFD and LF in PsA/PsO and the contribution of arthritis in their onset. PsA and PsO patients were consecutively enrolled. Exclusion criteria were liver diseases causing fibrosis (except NAFLD), alcohol ≥ 20 g/day, daily use of non-steroidal anti-inflammatory drugs and current/previous methotrexate use. Clinical history, biochemical and clinimetrical data and insulin-resistance index HOMA (homeostatic model assessment) were assessed. Patients underwent a liver ultrasound to identify steatosis (therefore NAFLD) and transient elastography, to evaluate LF (stiffness≥ 7 kPa = fibrosis). Statistical analysis included basic statistics, logistic and linear regression analyses (to assess the contribution of arthritis to NAFLD and LF grading, respectively) and Spearman's correlations; p ≤ 0.05 was considered significant. Seventy-six patients were enrolled (PsA/PsO 43/33). MetS and LF prevalence were similar between PsA and PsO (35% vs 33%, p = 0.88; 31% vs 28%, p = 0.77, respectively). NAFLD was more frequent in PsO (65% vs 35%, p = 0.044). In multivariable models with NAFLD and LF grading as outcomes, arthritis was not a significant predictor, while HOMA was independently associated with both (OR 1.34; 95%CI 1.06, 1.69; beta 0.88; 95%CI 0.54, 1.21, respectively). Female sex was independently associated with LF grading (beta 1.81; 95%CI 0.05, 3.57). NAFLD was more frequent in PsO, but MetS and LF prevalence were similar in PsA and PsO. Insulin resistance is the main determinant of NAFLD and LF, while additional contribution of arthritis seems small. Key Points • The prevalence of metabolic comorbidities, including liver fibrosis, is overall quite similar between psoriatic arthritis and psoriasis. • NAFLD is more frequently found in psoriasis than psoriatic arthritis. • The contribution of arthritis in the onset of metabolic comorbidities seems small.