Background and aims This study assessed: (1) the relationships among the risk factors for and components of metabolic syndrome (MetS) and health-related quality of life (HRQOL), and (2) the effects of these variables on HRQOL in a hypothesised causal model using structural equation modelling (SEM) in patients with systemic lupus erythematosus (SLE).

Methods Of the 505 SLE patients enrolled in the Korean Lupus Network (KORNET registry), 244 had sufficient data to assess the components of MetS at enrollment. Education level, monthly income, corticosteroid dose, Systemic Lupus Erythematosus Disease Activity Index, Physicians’ Global Assessment, Beck Depression Inventory, MetS components, and the Short Form-36 at the time of cohort entry were determined. SEM was used to test the causal relationship based on the Analysis of Moment Structure.

Results The average age of the 244 patients was 40.7±11.8 years. The SEM results supported the good fit of the model (χ² = 71.629, p=0.078, RMSEA 0.034, CFI 0.972). The final model showed a direct negative effect of higher socioeconomic status and a positive indirect effect of higher disease activity on MetS, the latter through corticosteroid dose. MetS did not directly impact HRQOL but had an indirect negative impact on it, through depression.

Conclusions In our causal model, MetS risk factors were related to MetS components. The latter had a negative indirect impact on HRQOL, through depression. Clinicians should consider socioeconomic status and medication and seek to modify disease activity, MetS, and depression to improve the HRQOL of SLE patients.