Nutritional impairment in juvenile idiopathic arthritis

Objective. To investigate the relationship between nutritional impairment, measured by body mass index (BMI), expressed as an age- and sex-standardized standard deviation score (BMI SDS), and disease and patient characteristics in a UK cohort of children with juvenile idiopathic arthritis (JIA). A subgroup with available dietary information were analysed separately. Methods. Important disease and patient characteristics (age, gender, disease subtype, swollen joint count, painful joint count, restricted joint count, treatment and dietary assessment) were assessed as potential explanatory measures of BMI SDS in a multiple linear regression. Results. Data were collected on 123 consecutive patients. Twenty were nutritionally impaired. In multiple regression analysis excluding the dietary data, disease subtype [persistent oligoarthritis and polyarthritis (rheumatoid factor-negative)], five or more joints with reduced range of movement and being younger were associated with lower BMI SDS (P<0.001). When energy and protein intake were included in the analysis for a subgroup of children, the resulting model retained only disease subtype as a predictor of a low BMI SDS (P = 0.013). Conclusions. In this unselected population of children with JIA, 16% had evidence of undernutrition. The most commonly affected subtype was oligoarthritis, a previously unreported finding. There is no evidence from this study that this nutritional impairment results from inadequate food intake and it is likely that it is multifactorial in aetiology, disease subtype being the most important factor.