Comparability of inflammation-adjusted Vitamin A deficiency estimates and variance in retinol explained by c-reactive protein and á1-acid glycoprotein during low and high malaria transmission seasons in rural zambian children

Maxwell A. Barffour, Kerry J Schulze, Christian L. Coles, Justin Chileshe, Ngandwe Kalungwana, Margia Arguello, Ward Siamusantu, William J Moss, Keith West, Amanda C Palmer

Research output: Contribution to journalArticle

Abstract

Inflammation-induced hyporetinolemia (IIH), a reduction in serum retinol (SR) during inflammation, may bias population estimates of vitamin A deficiency (VAD). The optimal adjustment for IIH depends on the type and extent of inflammation. In rural Zambian children (4-8 years, N = 886), we compared three models for defining inflammation: á-1- A cid glycoprotein (AGP) only (inflammation present if > 1 g/L or normal if otherwise), C-reactive protein (CRP) only (moderate inflammation, 5-15 mg/L; high inflammation, > 15 mg/L; or normal if otherwise) and a combined model using both AGP and CRP to delineate stages of infectious episode. Models were compared with respect to 1) the variance in SR explained and 2) comparability of inflammation-adjusted VAD estimated in low and high malaria seasons. Linear regression was used to estimate the variance in SR explained by each model and in estimating the adjustment factors used in generating adjusted VAD (retinol < 0.7 ìmol/L). The variance in SRexplained were2%(AGP-only),11%(CRP-only), and 11%(AGP-CRP) in the low malaria season; and2%(AGP-only),15%(CRP-only), and12%(AGP-CRP) in the high malaria season. Adjusted VAD estimates in the low and high malaria seasons differed significantly for the AGP (8.2 versus 13.1%) and combined (5.5 versus 9.1%) models but not the CRP-only model (6.1 versus 6.3%). In the multivariate regression, a decline in SR was observed with rising CRP (but not AGP), in both malaria seasons (slope = .0.06; P < 0.001). In this malaria endemic setting, CRP alone, as opposed to CRP and AGP, emerged as the most appropriate model for quantifying IIH.

Original languageEnglish (US)
Pages (from-to)334-343
Number of pages10
JournalAmerican Journal of Tropical Medicine and Hygiene
Volume98
Issue number1
DOIs
StatePublished - Jan 1 2018

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Vitamin A Deficiency
Vitamin A
C-Reactive Protein
Malaria
Glycoproteins
Inflammation
Acids
Proteins
Serum
Staphylococcal Protein A
Linear Models

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases
  • Virology

Cite this

@article{7803e16d47534ff6b159055202d6040f,
title = "Comparability of inflammation-adjusted Vitamin A deficiency estimates and variance in retinol explained by c-reactive protein and {\'a}1-acid glycoprotein during low and high malaria transmission seasons in rural zambian children",
abstract = "Inflammation-induced hyporetinolemia (IIH), a reduction in serum retinol (SR) during inflammation, may bias population estimates of vitamin A deficiency (VAD). The optimal adjustment for IIH depends on the type and extent of inflammation. In rural Zambian children (4-8 years, N = 886), we compared three models for defining inflammation: {\'a}-1- A cid glycoprotein (AGP) only (inflammation present if > 1 g/L or normal if otherwise), C-reactive protein (CRP) only (moderate inflammation, 5-15 mg/L; high inflammation, > 15 mg/L; or normal if otherwise) and a combined model using both AGP and CRP to delineate stages of infectious episode. Models were compared with respect to 1) the variance in SR explained and 2) comparability of inflammation-adjusted VAD estimated in low and high malaria seasons. Linear regression was used to estimate the variance in SR explained by each model and in estimating the adjustment factors used in generating adjusted VAD (retinol < 0.7 {\`i}mol/L). The variance in SRexplained were2{\%}(AGP-only),11{\%}(CRP-only), and 11{\%}(AGP-CRP) in the low malaria season; and2{\%}(AGP-only),15{\%}(CRP-only), and12{\%}(AGP-CRP) in the high malaria season. Adjusted VAD estimates in the low and high malaria seasons differed significantly for the AGP (8.2 versus 13.1{\%}) and combined (5.5 versus 9.1{\%}) models but not the CRP-only model (6.1 versus 6.3{\%}). In the multivariate regression, a decline in SR was observed with rising CRP (but not AGP), in both malaria seasons (slope = .0.06; P < 0.001). In this malaria endemic setting, CRP alone, as opposed to CRP and AGP, emerged as the most appropriate model for quantifying IIH.",
author = "Barffour, {Maxwell A.} and Schulze, {Kerry J} and Coles, {Christian L.} and Justin Chileshe and Ngandwe Kalungwana and Margia Arguello and Ward Siamusantu and Moss, {William J} and Keith West and Palmer, {Amanda C}",
year = "2018",
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TY - JOUR

T1 - Comparability of inflammation-adjusted Vitamin A deficiency estimates and variance in retinol explained by c-reactive protein and á1-acid glycoprotein during low and high malaria transmission seasons in rural zambian children

AU - Barffour, Maxwell A.

AU - Schulze, Kerry J

AU - Coles, Christian L.

AU - Chileshe, Justin

AU - Kalungwana, Ngandwe

AU - Arguello, Margia

AU - Siamusantu, Ward

AU - Moss, William J

AU - West, Keith

AU - Palmer, Amanda C

PY - 2018/1/1

Y1 - 2018/1/1

N2 - Inflammation-induced hyporetinolemia (IIH), a reduction in serum retinol (SR) during inflammation, may bias population estimates of vitamin A deficiency (VAD). The optimal adjustment for IIH depends on the type and extent of inflammation. In rural Zambian children (4-8 years, N = 886), we compared three models for defining inflammation: á-1- A cid glycoprotein (AGP) only (inflammation present if > 1 g/L or normal if otherwise), C-reactive protein (CRP) only (moderate inflammation, 5-15 mg/L; high inflammation, > 15 mg/L; or normal if otherwise) and a combined model using both AGP and CRP to delineate stages of infectious episode. Models were compared with respect to 1) the variance in SR explained and 2) comparability of inflammation-adjusted VAD estimated in low and high malaria seasons. Linear regression was used to estimate the variance in SR explained by each model and in estimating the adjustment factors used in generating adjusted VAD (retinol < 0.7 ìmol/L). The variance in SRexplained were2%(AGP-only),11%(CRP-only), and 11%(AGP-CRP) in the low malaria season; and2%(AGP-only),15%(CRP-only), and12%(AGP-CRP) in the high malaria season. Adjusted VAD estimates in the low and high malaria seasons differed significantly for the AGP (8.2 versus 13.1%) and combined (5.5 versus 9.1%) models but not the CRP-only model (6.1 versus 6.3%). In the multivariate regression, a decline in SR was observed with rising CRP (but not AGP), in both malaria seasons (slope = .0.06; P < 0.001). In this malaria endemic setting, CRP alone, as opposed to CRP and AGP, emerged as the most appropriate model for quantifying IIH.

AB - Inflammation-induced hyporetinolemia (IIH), a reduction in serum retinol (SR) during inflammation, may bias population estimates of vitamin A deficiency (VAD). The optimal adjustment for IIH depends on the type and extent of inflammation. In rural Zambian children (4-8 years, N = 886), we compared three models for defining inflammation: á-1- A cid glycoprotein (AGP) only (inflammation present if > 1 g/L or normal if otherwise), C-reactive protein (CRP) only (moderate inflammation, 5-15 mg/L; high inflammation, > 15 mg/L; or normal if otherwise) and a combined model using both AGP and CRP to delineate stages of infectious episode. Models were compared with respect to 1) the variance in SR explained and 2) comparability of inflammation-adjusted VAD estimated in low and high malaria seasons. Linear regression was used to estimate the variance in SR explained by each model and in estimating the adjustment factors used in generating adjusted VAD (retinol < 0.7 ìmol/L). The variance in SRexplained were2%(AGP-only),11%(CRP-only), and 11%(AGP-CRP) in the low malaria season; and2%(AGP-only),15%(CRP-only), and12%(AGP-CRP) in the high malaria season. Adjusted VAD estimates in the low and high malaria seasons differed significantly for the AGP (8.2 versus 13.1%) and combined (5.5 versus 9.1%) models but not the CRP-only model (6.1 versus 6.3%). In the multivariate regression, a decline in SR was observed with rising CRP (but not AGP), in both malaria seasons (slope = .0.06; P < 0.001). In this malaria endemic setting, CRP alone, as opposed to CRP and AGP, emerged as the most appropriate model for quantifying IIH.

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