Accounting for the influence of inflammation on retinol‐binding protein in a population survey of Liberian preschool‐age children

• Published in: Maternal and child nutrition Vol. 13; no. 2
• Main Authors: Larson, Leila Margaret, Addo, O. Yaw, Sandalinas, Fanny, Faigao, Katherine, Kupka, Roland, Flores‐Ayala, Rafael, Suchdev, Parminder S.
• Format: Journal Article
• Language: English
• Published: England John Wiley and Sons Inc 01.04.2017
• Subjects: alpha1‐acid glycoprotein; Biomarkers - blood; C-Reactive Protein - metabolism; Child, Preschool; Cross-Sectional Studies; C‐reactive protein; Hemoglobins - metabolism; Humans; Infant; inflammation; Inflammation - epidemiology; Liberia - epidemiology; Morbidity; nutrition; Nutritional Status; Original; Orosomucoid - metabolism; Prevalence; Retinol-Binding Proteins - metabolism; retinol‐binding protein; Vitamin A - blood; vitamin A deficiency; Vitamin A Deficiency - blood; Vitamin A Deficiency - epidemiology; alpha1-acid glycoprotein; nutrition; retinol-binding protein; C-reactive protein; inflammation; vitamin A deficiency
• ISSN: 1740-8695; 1740-8709
• DOI: 10.1111/mcn.12298

Vitamin A deficiency (VAD) is an important contributor to child morbidity and mortality. The prevalence of VAD, measured by retinol‐binding protein (RBP) or retinol, is overestimated in populations with a high prevalence of inflammation. We aimed to quantify and adjust for the effect of inflammation on VAD prevalence in a nationally representative survey of Liberian children 6 to 35 months of age. We compared five approaches to adjust RBP for inflammation and estimate VAD prevalence (defined as RBP < 0.7 µmol/L): (1) ignoring inflammation; (2) excluding individuals with inflammation (C‐reactive protein (CRP) >5 mg/L or alpha1‐acid glycoprotein (AGP) >1 g/)L; (3) multiplying each individual's RBP by an internal correction factor; (4) by an external correction factor; and (5) using regression (corrected RBP = exp(InRBP – β1(lnCRPobs‐lnCRPref) – β2(lnAGPobs‐lnAGPref)). Corrected RBP was based on a regression model where reference lnCRP and lnAGP were set to the maximum of the lowest decile. The unadjusted prevalence of VAD was 24.7%. Children with elevated CRP and/or AGP had significantly lower RBP concentrations than their apparently healthy peers (geometric mean RBP 0.79 µmol/L (95% CI: 0.76, 0.82) vs. 0.95 µmol/L (95% CI: 0.92, 0.97), P < 0.001). Using approaches 2–5 resulted in a prevalence of VAD of 11.6%, 14.3%, 13.5% and 7.3%, respectively. Depending on the approach, the VAD prevalence is reduced 10–17 percentage points when inflammation is taken into account. Further quantification of the influence of inflammation on biomarkers of vitamin A status from other national surveys is needed to compare and recommend the preferred adjustment approach across populations.