Effects of Early Neonatal Administration of Lactiplantibacillus plantarum ATCC 202195 on the Fecal Microbiota of Infants in Dhaka, Bangladesh

Objectives: Biomarker measurements are subject to intra-individual variation but the implications for prevalence assessment are uncertain.We assessed agreement between repeated biomarker measurements (3-wk interval) and whether adjustment for intra-individual variation influenced prevalence estimates.Methods: Participants were children 24-59 mo of age enrolled in the control group of a trial in northern Ghana, whose households received iodine-fortified bouillon cubes for 9 mo.Children with biomarker data at intervention wks 35 and 38 were included (n316).Hemoglobin (Hb) was measured in venous blood by Hemocue 301+.Plasma ferritin (Fer) and soluble transferrin receptor (sTfR) were assessed by ELISA; Fer was adjusted for inflammation.Agreement was assessed by Spearman correlations (rho), Bland-Altman plots, and t-tests.We compared anemia (Hb < 11 g/L) and iron deficiency (ID, Fer < 12 g/L or sTfR > 8.3 mg/L) between time points by Chi-square test and calculated percent agreement.The National Cancer Institute method, via the SIMPLE macro, was used to estimate "usual" biomarker concentration and prevalence of anemia and ID.Results: Biomarker concentrations at the two time points were correlated (Hb: rho0.78,Fer: rho0.84;sTfR: rho0.91;all P< 0.001) and means did not differ (P >0.05).Anemia was 19.9% at wk35 and 19.1% at wk38, and agreement was 84.5%; 11.6% (n36) had anemia at both time points.ID based on Fer was 53.2% at wk35, 51.6% at wk38, and agreement was 83.2% (44% with ID at both time points); for sTfR, corresponding values were 52.2%, 51.6%, and 88.6% (46% with ID at both time points).Intra-individual variation comprised 22.1% of total variation in Hb concentration, 17.7% for Fer, and 7.4% for sTfR.Prevalence of anemia based on the estimated "usual" Hb distribution was 20.8%, and "usual" ID was 49.6% for Fer and 57.7% for sTfR.Conclusions: Repeated measurements of Hb and iron biomarkers and related prevalences showed overall agreement in this sample, although ~11-17% of children changed status after three weeks.Adjusting the biomarker distribution for intra-individual variation had little impact on estimated prevalence of anemia or ID, suggesting that a single measure is sufficient for prevalence estimates.