Background/Purpose: Psoriatic arthritis (PsA) is a chronic inflammatory disease which affects the skin and musculoskeletal system. PsA patients frequently suffer from comorbidities: cardiovascular disease, metabolic syndrome, inflammatory bowel disease, liver disease, osteoporosis, malignancy, and ophthalmic disease. Among PsA patients, the prevalence of biochemical liver abnormalities has been reported as 24-36%. We aimed to determine the prevalence and incidence of liver abnormalities and identify the factors associated with liver abnormalities in PsA patients.

Methods: Patients with PsA have been followed prospectively according to a standard protocol which includes detailed clinical and laboratory tests collected at 6-12 month intervals. From this longitudinal cohort study we identified PsA patients with either elevated (>1.5x normal) serum transaminase or alkaline phosphatase levels or liver disease (fatty liver, viral hepatitis, autoimmune liver disease, alcoholic liver disease, liver fibrosis, and cirrhosis) after the first visit to the PsA clinic (cases). Controls were subjects from the same cohort who never had such abnormalities or liver disease. Cases and controls were then matched 1:1 by sex, age at the first clinic visit, and follow-up duration. Variables at the first appearance of liver test abnormality were evaluated using univariable and multivariable regression analyses to identify the factors associated with liver abnormalities after controlling for demographic variables, disease activity, and treatment.

Results: Among 1061 patients followed in the PsA clinic, 343 had liver abnormalities.  256 patients who developed liver abnormalities after the first visit were identified as cases, 718 patients were identified as controls. The prevalence of liver abnormalities was 32% and the incidence was 39/1000 patient-years. Among 256 cases, the mean age (s.d.) of PsA patients at the onset of liver abnormalities was 50.5 ± 12.8 years. Liver abnormalities were detected after mean (s.d.) follow up duration of 8.3 ±7.8 years. Twenty-nine percent of cases had an identified cause of liver biochemical abnormalities. The common causes of liver abnormalities were drug induced hepatitis (14%) and fatty liver (13%). Multivariable analysis in matched case-control study (204 pairs) revealed that higher BMI, daily alcohol intake, higher damaged joint count, elevated C-reactive protein (CRP), use of methotrexate (MTX), leflunomide (LFN) or TNF inhibitors were independent factors associated with liver abnormalities (Table 1).

Conclusion: The prevalence of liver abnormalities among PsA was 32% and the incidence was 39/1000 patient-years. Higher BMI, daily alcohol intake, more damage joint count, elevated CRP, use of MTX/LFN or TNF inhibitors are associated with liver abnormalities in PsA patients.   Monitoring liver function tests in these high risk patients is recommended.