Antibiotic use and childhood body mass index trajectory.

BACKGROUND/OBJECTIVES: Antibiotics are commonly prescribed for children. Use of antibiotics early in life has been linked to weight gain but there are no large-scale, population-based, longitudinal studies of the full age range among mainly healthy children. SUBJECTS/METHODS: We used electronic health record data on 163 820 children aged 3-18 years and mixed effects linear regression to model associations of antibiotic orders with growth curve trajectories of annual body mass index (BMI) controlling for confounders. Models evaluated three kinds of antibiotic associations-reversible (time-varying indicator for an order in year before each BMI), persistent (time-varying cumulative orders up to BMIj) and progressive (cumulative orders up to prior BMI (BMIj-1))-and whether these varied by age. RESULTS: Among 142 824 children under care in the prior year, a reversible association was observed and this short-term BMI gain was modified by age (P<0.001); effect size peaked in mid-teen years. A persistent association was observed and this association was stronger with increasing age (P<0.001). The addition of the progressive association among children with at least three BMIs (n=79 752) revealed that higher cumulative orders were associated with progressive weight gain; this did not vary by age. Among children with an antibiotic order in the prior year and at least seven lifetime orders, antibiotics (all classes combined) were associated with an average weight gain of approximately 1.4 kg at age 15 years. When antibiotic classes were evaluated separately, the largest weight gain at 15 years was associated with macrolide use. CONCLUSIONS: We found evidence of reversible, persistent and progressive effects of antibiotic use on BMI trajectories, with different effects by age, among mainly healthy children. The results suggest that antibiotic use may influence weight gain throughout childhood and not just during the earliest years as has been the primary focus of most prior studies.

Decreased physical function in juvenile rheumatoid arthritis.

OBJECTIVE: To assess the extent of physical disability in juvenile rheumatoid arthritis (JRA), classified according to subtype, and whether synovitis or flexion contractures are present on examination. METHODS: This retrospective study included 88 JRA patients and 50 controls without musculoskeletal disease. The outcome measure was the disability index (DI) derived from the Childhood Health Assessment Questionnaire (CHAQ). RESULTS: DI scores for JRA patients with synovitis (mean 0.49, range 0-1.88) and without synovitis (mean 0.37, range 0-1.75) were significantly higher (P < 0.001 for both groups) than for controls (mean 0.06, range 0-0.75, P < 0.001), but not significantly different from one another. Similarly, DI scores for JRA patients with and without any flexion contractures were higher than for controls, but not significantly different from one another. DI scores for JRA patients with both synovitis and flexion contractures were significantly higher than DI scores for JRA patients with neither, but were not distinguishable from JRA patients with synovitis only or flexion contractures only. Likewise, DI scores for JRA patients lacking synovitis and flexion contractures were not significantly different than those for JRA patients with one or the other. DI scores for systemic and polyarticular patients were higher than for pauciarticular patients, and DI scores for all 3 subtypes were higher than for controls. CONCLUSION: Our findings suggest that many JRA patients, including those with pauciarticular JRA, have problems with physical function, even when synovitis and flexion contractures are not present. Further attention and research is needed to elucidate the causes or origins of disability in JRA patients with seemingly well-controlled disease. We recommend that health status instruments like the CHAQ be more widely used for JRA patients to complement other assessments, especially in planning occupational and physical therapy.