High prevalence and distinct patterns of metabolic syndrome in rheumatoid arthritis, psoriatic arthritis, and axial spondyloarthritis: a population-based study.

Introduction: Metabolic syndrome (MetS) in inflammatory arthritis (IA) directly impacts its management and associated morbidity and mortality. MetS is a well-recognised comorbidity in PsA, but the epidemiology across IA is unclear. This study aimed to characterise the prevalence of MetS across rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) compared to controls.

Methods: We performed a cross-sectional analysis of half a million individuals from the UK Biobank, aged 40 to 69 years, who were collected between 2006 and 2010. Participants with RA, PsA, and axSpA were identified using ICD-10 codes and/or read codes. MetS was defined according to adapted National Cholesterol Education Program Adult Treatment Panel III criteria. Statistical analysis included ANOVA and chi-squared test for between-group difference and logistic regression for odds of MetS, adjusted for age, sex, CRP and smoking status.

Results: The prevalence of MetS was highest in RA (43.4%), followed by PsA (42.3%), axSpA (37.1%) and controls (31.8%). Hypertension was prevalent across all IAs (~ 80%), as was hypertriglyceridaemia. Elevated waist circumference and dysglycaemia were more prevalent in RA and PsA compared to axSpA. The adjusted odds of comorbid MetS were elevated in RA (OR 1.15; 95% CI 1.07, 1.24; p < 0.001) and PsA (OR 1.31; 95% CI 1.13, 1.52; p < 0.001) compared to controls, but decreased in axSpA (OR 0.82; 95% CI 0.70, 0.96; p = 0.012).

Conclusion: RA and PsA, but not axSpA, are associated with an increased odds of MetS. Holistic management strategies that address both IA and MetS are essential for improving mortality and morbidity.