Predictors of Inflammation in a Cohort of Bolivian Infants and Toddlers

Abstract

Inflammation has been associated with cardiovascular disease and other health outcomes in children and adults, yet few longitudinal data are available on prevalence and predictors of inflammation in infants. We aimed to identify the prevalence of inflammation in a cohort of Bolivian infants and estimate its association with acute (recent illnesses) and chronic (overweight, stunting) morbidities and potential pathogen exposure (represented by water, sanitation, and hygiene [WASH] resources). We measured plasma concentrations of two acute phase proteins (C-reactive protein [CRP], marking acute inflammation, and alpha(1)-acid-glycoprotein [AGP], marking chronic inflammation) at three time points (target 2, 6-8, and 12-18 months). Of 451 singleton infants enrolled in the parent study, 272 had the first blood draw and complete data. Anthropometry and sociodemographic and recent illness data (2-week recall of cough, diarrhea, and fever) were collected at each visit. Inflammation was defined as CRP > 5 mg/L or AGP > 1 g/L. The prevalence of inflammation increased from early infancy (3% at first blood draw) to later infancy (15-22% at later blood draws). Recent cough, recent fever, and age in months were significantly associated with relative increases in CRP (7-44%) and AGP (5-23%), whereas recent diarrhea was only significantly associated with an increase in CRP (48%). Neither anthropometry nor WASH was significantly associated with inflammation. Results confirm the role of recent acute illness in inflammation in infants, and indicate that adiposity and WASH are not as important to inflammation in this age category.

Figure 1.

Of 2,331 screened mother–infant pairs, 1,336 were eligible and 461 enrolled. A total of 365 singleton infants provided samples at 2months, but only 272 were included in the present analysis due to missing data. Of these, 239 had blood drawn at 6–8 months, and 126 at 12–18months of age. There were 121 infants with samples at all three time points. *Third blood draw was added after a secondary aim was funded, see Methods section.

Figure 2.

Most of the blood draws (dark gray bars) fell within the target age ranges (light gray bands), with the highest success in the first blood draw.

Figure 3.

The distribution of infant AGP and CRP was right shifted for ages older than 2 months. Both biomarkers of inflammation were right skewed. The x axes are shown on the log scale. The y axes indicate the percent of observations within each visit at each level of AGP and CRP. AGP = alpha(1)-acid glycoprotein; CRP = C-reactive protein.