Background Psoriatic arthritis (PsA) and psoriasis (PsO) are commonly associated to various comorbidities, among which metabolic syndrome (MetS) has been demonstrated to be more prevalent in these groups with respect to the general population. However, few data are available regarding the comparison between PsA/PsO. Besides, a possible consequence of MetS is the development of a non-alcoholic fatty liver disease (NAFLD), which can progress to fibrosis, the latter rarely assessed in PsA/PsO.
Objectives The aim of this case-control study was: 1) to compare prevalence of MetS in PsA and PsO 2) to evaluate the presence of liver fibrosis in these two groups using hepatic elastography.
Methods Forty-three consecutive PsA patients classified according to ClASsification criteria for Psoriatic ARtritis (CASPAR), and 33 consecutive PsO patients without history/manifestations of arthritis, attending the Rheumatology and Dermatology Units of University of Padua, were studied. Exclusion criteria were: conditions which may cause liver fibrosis other than NALFD (eg viral hepatitis, autoimmune or genetic liver disease), alcohol consumption >20 grams/day, active smoking, daily use of non-steroidal anti-inflammatory drugs. Anamnestic, laboratory (cholesterol, triglycerides, uric acid, fasting glucose, insulin, albumin, transaminase) and metrological (blood pressure, waist circumference, height, weight) data were collected. MetS was defined according to the criteria of National Cholesterol Education Program's Adult Treatment Panel III report. Insuline resistance was quantified through HOMA (Homeostatic Model Assessement). All patients underwent hepatic elastography to evaluate liver stiffness; values >7 kPa were taken as indicator of liver fibrosis. PsO severity was assessed through Psoriasis area severity index (PASI). Differences in variables between PsA/PsO were compared through non parametric Mann-Whitney test, and Chi-square test for categorical variables. Correlations between variables were evaluated through Spearman test.
Results PsA and PsO patients showed similar characteristics (mean age 60,2±8,4 vs 54,5±19,6 years, 74,4% vs 63% males, artritis/PsO duration 12,6±8,5 vs 18,2±14,2 years). The only variables which differ in PsA/PsO groups were Body Mass Index (BMI) (25,7±3,4vs 29,1±6,3), PASI (5±4,6 e 1,5±2,5) and serum uric acid (4,9±1,5 vs 5,7±1,4 mg/dL), all higher in PsO (p-values 0,0092, 0,0355 and 0,0001 respectively). Prevalence of MetS and liver fibrosis in the 2 groups were was similar: 34,9% and 30,8% in PsA vs 33,3% and 27,6% in PsO (p=ns). Among all correlation studied, only serum uric acid, liver stiffness and PASI correlated with other variables (Table). Most interestingly, liver stiffness very well correlated with serum uric acid in PsO (p<0,0001 r=0,73).
Conclusions We observed a similar prevalence of MetS and hepatic stiffness in PsA and PsO. The correlation found between uric acid level and hepatic stiffness could lie on the fact that uric acid seems to favour insulin resistance, hypertension, dyslipidemia and other MetS risk factors. MetS could be therefore one of the major determinants to liver fibrosis in PsA and PsO, thus highlighting how comorbidities are not only coexhisting conditions, but are strongly linked to each other and need to be treated as well as the skin and joint aspect.
Disclosure of Interest None declared