Inactive Disease in Enthesitis-related Arthritis: Association of Increased Body Mass Index.

Objective: Patients with enthesitis-related arthritis (ERA) were less likely to achieve and sustain inactive disease than children with other subtypes of juvenile idiopathic arthritis. The aim of this study was to evaluate the effect of increased body mass index (BMI) on clinical features of the disease and to investigate whether being overweight or obese limits the possibility of achieving clinically inactive disease in patients with ERA.

Methods: The hospital charts of 72 patients with ERA were reviewed. Demographic and clinical findings were recorded. Patients were divided into 2 groups according to whether they had "healthy weight" (BMI < 85th percentile) or "increased weight" (BMI ≥ 85th percentile) at baseline. The primary outcome of this study was to achieve inactive disease at 1 year after the initiation of therapy. The inactive disease criterion of Wallace, et al was used to define inactive disease status.

Results: Twenty patients had increased BMI. The frequency of tarsitis and ankle involvement was higher in patients with increased weight. Thirty-seven patients were inactive at the end of 1 year. In univariate analyses, male sex, increased BMI, ankle involvement, and tarsitis were found to be associated with failure to achieve inactive disease. Multivariate backward stepwise regression analyses revealed that failure to achieve clinically inactive disease was associated with increased BMI and ankle involvement.

Conclusion: Being overweight or obese was associated with failure to achieve inactive disease in patients with ERA. Because body weight is a modifiable factor, individualized interventions may have clinical implications for better therapeutic outcome.