C-Reactive Protein Concentration Predicts Change in Body Mass Index during Childhood

OBJECTIVE: Inflammation may constitute an underlying mechanism for increased risk of developing chronic diseases in later years, but few prospective studies have assessed the influence of low-grade inflammation on body weight gain, particularly among children in low- to middle-income settings with lower prevalence of overweight and obesity. We aimed to investigate whether C-reactive protein (CRP), as a biomarker of low-grade inflammation, predicts changes in body mass index-for-age z scores (BAZ) during childhood. METHODS: A population-based longitudinal study was conducted in the Brazilian Amazon among children aged ≤10 years in 2007, with follow-up visits in 2009 and 2012. Outcome was annual change in BAZ. As the main exposure of interest, CRP concentrations were divided into four categories, with values <1 mg/L divided in tertiles plus a fourth category with values ranging from 1 to 10 mg/L. Children were simultaneously screened for iron and vitamin A deficiencies, diarrhea, and wheezing. We used mixed-effect linear regression models to measure the effect of CRP concentrations on annual BAZ change and linear regression models to explore CRP predictors at baseline. RESULTS: At baseline, 1007 children had CRP and anthropometric data [mean (SD) age: 5.3 (2.9) years; 50.9% male, 84.5% mulatto/mixed-race, 14.0% at risk for overweight or obesity, 4.8% stunted]; 737 were successfully followed up. Morbidities and nutritional deficiencies were widespread. Among participants aged >5 years, children in the highest tertile of CRP <1 mg/L at baseline, regarded as an indicator of low-grade inflammation, had a 0.04 z/y higher gain in BAZ (95% CI: 0.01, 0.09 z/y) during follow-up. CRP was positively associated with household poverty and worse nutritional indicators. CONCLUSIONS: We found evidence of a role for low-grade inflammation in predicting annual BAZ gain among children aged >5 years.