Biomarkers Reflecting Inflammation And Nutritional Determinants Of Anemia Research Articles

A Practical Guide to Adjust Micronutrient Biomarkers for Inflammation Using the BRINDA Method

The Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) research group was formed over a decade ago to improve the interpretation of micronutrient biomarkers in settings with inflammation. The BRINDA inflammation adjustment method uses regression correction to adjust for the confounding effects of inflammation on select micronutrient biomarkers and has provided important insights to micronutrient research, policy, and programming. However, users may face challenges when applying the BRINDA inflammation adjustment methods to their own data due to varying guidance on the adjustment approach for different biomarkers and the need to develop statistical programming to conduct these analyses. This may result in lost opportunities to have results of micronutrient data readily available during critical decision-making periods. Our research objectives are to 1) provide an all-in-one summary of the BRINDA method in adjusting multiple micronutrient biomarkers for inflammation, 2) evaluate whether malaria as a binary variable should be included in the BRINDA inflammation adjustment method, and 3) present standardized and user-friendly BRINDA adjustment R package and SAS macro. This paper serves as a practical guidebook for the BRINDA inflammation adjustment approach and aids users to use the BRINDA R package and SAS to streamline their analyses.

Assessment of Vitamin D status and association with inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

BackgroundIt is unclear whether 25(OH)D concentrations in children and female adults may be influenced by inflammation and thus require adjustment when estimating the population prevalence of vitamin D deficiency. ObjectivesWe examined correlations between inflammation biomarkers, CRP or alpha-1-acid glycoprotein (AGP), and serum 25(OH)D concentrations among preschool children (PSC; 6–59 mo) and nonpregnant females of reproductive age (FRA; 15–49 y). MethodsWe analyzed cross-sectional data from 6 nationally representative nutrition surveys (Afghanistan, Cambodia, Pakistan, UK, USA, and Vietnam) conducted among PSC (n = 9880) and FRA (n = 14,749) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia project. Rank correlations between CRP or AGP and 25(OH)D concentrations were examined while taking into account complex survey design effects. ResultsAmong both PSC and FRA, correlations between inflammation and vitamin D biomarkers were weak and inconsistent across surveys. For PSC, correlation coefficients between CRP and 25(OH)D concentrations ranged from −0.04 to 0.08, and correlations between AGP and 25(OH)D ranged from 0.01 to 0.05. Correlation coefficients between CRP and 25(OH)D for FRA ranged from −0.11 to 0.14, and correlations between AGP and 25(OH)D concentrations ranged from −0.05 to 0.01. ConclusionsBased on the weak and inconsistent correlations between CRP or AGP and 25(OH)D, there is no rationale to adjust for these inflammation biomarkers when estimating population prevalence of vitamin D deficiency in PSC or FRA.

The Relationship Between Ferritin and BMI is Mediated by Inflammation Among Women in Higher-Income Countries, But Not in Most Lower-Income Countries Nor Among Young Children: A Multi-Country Analysis

In the presence of inflammation, the serum or plasma ferritin concentration ("ferritin" hereafter) transiently increases, confounding its interpretation as an iron status marker. The extent to which adiposity-related inflammation may influence ferritin interpretation is uncertain. We describe relationships between weight status, inflammation, and ferritin among nonpregnant women of reproductive age (WRA; 15-49 years) and preschool-age children (PSC; 6-59 months) with normal weight to overweight or obesity (OWOB) in differing geographic settings. Cross-sectional data were separately analyzed from 18 surveys (WRA) and 25 surveys (PSC) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project, excluding observations with underweight, wasting, pregnancy, or malaria. Relationships were assessed between BMI (in WRA) or BMI-for-age z-score (BAZ; in PSC), inflammatory biomarkers of C-reactive protein (CRP) and/or α-1-acid glycoprotein (AGP), ferritin by linear regression, and potential mediation by CRP and/or AGP in relationships between BMI or BAZ and ferritin with structural equation modeling. Regression and mediation models accounted for complex survey designs. Results were grouped by World Bank income classifications. In 5 of 6 surveys among WRA from upper-middle and high-income countries, ferritin was significantly positively associated with BMI, and this relationship was partially (or fully, in the United States) mediated by CRP and/or AGP. Mediation was present in 4 of 12 surveys for WRA in low- and lower-middle income countries. Among PSC, ferritin was positively associated with CRP and/or AGP in all surveys, but there were no significant CRP- or AGP-mediated relationships between ferritin and BAZ, except a negative relationship in the Philippines. Where having OWOB is common among WRA, measurements of inflammatory biomarkers and their uses in interpreting ferritin may improve iron status assessments. While these relationships were inconsistent among PSC, inflammation was common and should be measured to interpret iron status. Included Kenyan trial data are registered at clinicaltrials.gov as NCT01088958.

Median Urinary Iodine Concentration in School-Age Children Does Not Consistently Vary by Inflammation or Sociodemographic Factors: Multi-Country Analysis From BRINDA

ObjectivesIodine is an essential micronutrient that plays a critical role in child growth and development. This study aimed to examine median urinary iodine concentrations (mUIC) by country and key health and sociodemographic factors.MethodsNationally representative surveys from Bangladesh (n = 1282), Ecuador (n = 6063), Malawi (n = 758), and the U.S. (n = 3548) were analyzed to estimate mUIC among school-age children (6–12 years old) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project. WHO classifies mUICs into four categories: insufficient iodine intake, defined as mUIC < 100 μg/L; adequate iodine nutrition categorized as mUIC from 100 to 199 μg/L; above the required intake as mUIC from 200 to 299 μg/L; and excessive intake as mUIC >300 μg/L. Inflammation was defined by Alpha 1-acid glycoprotein (AGP) of >1 g/L or C-reactive protein (CRP) of >5 mg/L. Underweight was defined by Body Mass Index (BMI) for age z-score < −2 and overweight was defined as BMI z-score >2. Complex survey designs were applied to calculate the mUIC for each country. Design-based median tests were used to examine whether mUICs differed by age, sex, weight status, and inflammation status by country.ResultsmUIC was adequate in Bangladesh (138.5 μg/L) and above the required intake in Ecuador (251.0 μg/L), Malawi (265.5 μg/L), and the U.S. (230.0 μg/L). Boys had a significantly higher mUIC than girls in Ecuador (257.0 vs. 237.0 μg/L, P = 0.03), Malawi (302.0 vs. 226.8 μg/L, P = 0.01), and the U.S. (264.0 vs. 210.3 μg/L, P = 0.04). mUIC was not significantly different by age groups (6–9 vs. 10–12 years), weight status, and inflammation status, except in Bangladesh where the group with inflammation had a higher mUIC than the group without (153.0 vs. 130.0 μg/L, P = 0.04).ConclusionsAlthough heterogeneity existed in mUICs across different countries, iodine intake was adequate or above requirements in all four countries. Compared to girls, boys had higher mUIC in 3 countries, and the group with inflammation had higher mUIC in 1 country. mUIC did not differ by other socioeconomic or anthropometric factors.Funding SourcesBill & Melinda Gates Foundation, Centers for Disease Control and Prevention, Eunice Kennedy Shriver National Institute of Child Health and Human Development, HarvestPlus, and the United States Agency for International Development.

Prevalence and Predictors of Inflammation in Pregnant Women: Multi-Country Analysis From BRINDA Project

ObjectivesLimited data exist on the prevalence and predictors of inflammation during pregnancy. We aimed to characterize the inflammatory pattern and predictors of subclinical inflammation across pregnancy using multi-country analysis.MethodsThe Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project compiled 17 datasets of pregnant women (n = 14,077) from 15 countries in both high- and low-income settings. Datasets were included if at least one inflammation biomarker (C-reactive protein, CRP, or α-1-acid glycoprotein, AGP) were collected. We estimated the prevalence of any subclinical inflammation (defined as CRP >5 mg/L or AGP >1 g/L), examined AGP and CRP patterns throughout pregnancy, and assessed the relationship between inflammation and covariates such as maternal age, gestational age, socioeconomic, and water and sanitation factors for each dataset.ResultsThe prevalence of inflammation varied from 16.6% in Afghanistan to < 1% in Vietnam using elevated AGP and from 52.9% in the US to 7.6% in Vietnam using elevated CRP. Inflammation was common but varied across datasets: >40% in 5 datasets, 20–40% in 6 datasets, 10−< 20% in 5 datasets and < 10% in one dataset. AGP decreased with increasing gestational age (P < 0.01 in all seven datasets with gestational age information); however, the magnitude of decrease in AGP varied by country. In contrast, CRP showed an inconsistent pattern by gestational age. In multivariable models, the predictors of inflammation included age, trimester, urban or rural residence, socioeconomic status, improved sanitation, improved drinking water, lactating and smoking status, although strengths of association differed by dataset.ConclusionsAlthough there was considerable heterogeneity in the prevalence of inflammation, inflammation was common across pregnancy in diverse settings. AGP, a measure of long-term inflammation, decreased across pregnancy in all countries, whereas the pattern for CRP was inconsistent. The relationship between socioeconomic and health factors and inflammation varied across countries.Funding SourcesBill & Melinda Gates Foundation, Centers for Disease Control and Prevention, Eunice Kennedy Shriver National Institute of Child Health and Human Development, HarvestPlus, and the United States Agency for International Development.

Iron Status and Metabolic Health in Women of Reproductive Age in Southern India

ObjectivesTo examine the associations of iron status with metabolic health outcomes in women of reproductive age (WRA), as part of a population-based biomarker survey in Southern India. MethodsParticipants were WRA (15–40 y; n = 980) who were not pregnant or lactating (2017–2018). Blood samples were analyzed for hemoglobin (Hb; Coulter Counter) and glycated hemoglobin (HbA1c; nephelometry). Serum ferritin (SF) was measured by electrochemiluminescence; soluble transferrin receptor, C-reactive protein, and alpha-1 acid glycoprotein were analyzed via immuno-based assays (Roche). Anthropometric and blood pressure measurements were collected in triplicate. Bioelectrical impedance analysis (BC-418 MA) was used to estimate whole body (WF%) and trunk (TF%) fat in women ≥ 18y. Anemia was defined as Hb < 12.0 g/dL. SF was adjusted for inflammation using Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) methods; iron deficiency (ID) was defined as SF < 15.0 μg/L. Linear and binomial regression were used to examine associations of iron status with metabolic outcomes. ResultsA total of 41.5% of WRA had anemia, and 46.3% had ID (61.5%; BRINDA-adjusted). A total of 23.3% of adults were overweight (BMI: 25.0-<30.0 kg/m2) and 9.6% had obesity (BMI ≥ 30.0 kg/m2). Waist circumference (WC; ≥88.9 cm) and waist-hip ratio (WHR; ≥0.85) were elevated in 13.4% and 20.8% of women, and 25.0% had elevated HbA1c (≥6.5%: 5.0%; ≥5.7-<6.5%: 20.0%). Higher Hb concentrations were associated with increased BMI (β: 0.42 [SE: 0.09]; p < 0.01), WC (0.77 [0.21]; p < 0.01), and WF% (0.89 [0.17]; p < 0.01). Higher SF levels were associated with higher WF% (β: 0.79 [SE: 0.32]; p = 0.01) and TF% (0.92 [0.39]; p = 0.02), and elevated WC (RR: 1.20 [95% CI: 1.02–1.42]). Iron status was not significantly associated with HbA1c or blood pressure. ConclusionsThe burden of adverse metabolic outcomes was substantial in this population. Higher iron status was associated with higher BMI and central adiposity. Evaluating iron status and metabolic outcomes in future studies could help inform screening and interventions to improve the health of WRA. Funding SourcesCenters for Disease Control and Prevention (5U01DD001007), University of South Carolina Disability Research and Dissemination Center; Consejo Nacional de Ciencia y Tecnología (CEGL); NIH 5T32HD087137 (AF); NIH T32DK007158 (HMG).

Limits of Detection in Acute-Phase Protein Biomarkers Affect Inflammation Correction of Serum Ferritin for Quantifying Iron Status among School-Age and Preschool-Age Children and Reproductive-Age Women

BackgroundStandardized practices are needed in the analysis of inflammation biomarker values outside limits of detection (LODs) when used for inflammation correction of nutritional biomarkers. ObjectiveWe assessed the direction and extent to which serum C-reactive protein (CRP) and α-1-acid-glycoprotein (AGP) values outside LODs (<0.05 mg/L and >4.0 g/L, respectively) affect inflammation regression correction of serum ferritin and compared approaches to addressing such values when estimating inflammation-adjusted ferritin and iron deficiency (ID). MethodsWe examined 29 cross-sectional datasets from 7 countries with reproductive-age women (age 15–49 y) (n = 12,944), preschool-age children (age 6–59 mo) (n = 18,208), and school-age children (age 6–14 y) (n = 4625). For each dataset, we compared 6 analytic approaches for addressing CRP <LOD: listwise deletion, single imputation (lower, middle, or upper bound; LOD/√2; random number), with multiple imputation (MI). For each approach, inflammation-adjusted ferritin and ID using BRINDA (Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia) regression correction were estimated. We calculated deviance of each estimate from that given by MI within each dataset and performed fixed-effects multivariate meta-regression with an analytic approach as a moderator to compare the reliability of each approach to MI. ResultsAcross datasets, observations outside LOD ranged from 0.0 to 35.0% of CRP values and 0.0 to 2.5% of AGP values. Pooled deviance estimates for mean ferritin (μg/L) and ID (percentage points) were: listwise deletion −0.46 (95% CI: −0.76, −0.16) and 0.14 (−0.43, 0.72), lower bound 0.45 (0.14, 0.76) and −0.36 (−0.91, 0.20), middle bound −0.21 (−0.51, 0.09) and 0.22 (−0.34, 0.79), LOD/√2 −0.26 (−0.57, 0.04) and 0.25 (−0.31, 0.81), upper bound −0.31 (−0.61, −0.01) and 0.30 (−0.27, 0.86), and random number −0.08 (−0.38, 0.22) and 0.11 (−0.46, 0.67). There was moderation by approach in the ferritin model (P < 0.001). ConclusionsThese findings demonstrate the need for standardized analyses of inflammation biomarker values outside LODs and suggest that random number single imputation may be a reliable and feasible alternative to MI for CRP <LOD.

Iron deficiency and blood cadmium concentrations in a cohort of reproductive-age women

BACKGROUND AND AIM: In reproductive-age women, iron deficiency is common. When iron stores are low, gut metal ion transporters are upregulated to increase intestinal absorption of dietary iron. However, this mechanism can also increase absorption of cadmium in the diet. METHODS: We investigated the association between iron deficiency and blood cadmium concentrations using enrollment data (years 2010-2012) from the Study of Environment, Lifestyle & Fibroids, a cohort of 1,693 Black women ages 23-35 years who reside in the Detroit, Michigan area. Since cadmium exposure from cigarette smoking occurs via inhalation and not intestinal absorption, we restricted the study population to non-pregnant, never-smokers (n=1242). Cadmium and ferritin concentrations were measured in whole blood and serum samples, respectively, from 1120 participants. We adjusted the serum ferritin concentrations using high-sensitivity C-reactive protein and the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) internal regression correction approach to account for inflammation. We defined iron deficiency as adjusted serum ferritin concentrations 15 µg/L. Multivariable linear regression was conducted to estimate the percent difference in blood cadmium concentrations in relation to iron deficiency, adjusting for age, education, and passive cigarette smoke exposure. RESULTS:The geometric mean (GM) blood cadmium concentration in our sample was 0.22 µg/L (95% CI: 0.21-0.23), similar to that reported in NHANES 2011-2012 among Black women of the same age who never smoked (GM 0.24, 95% CI: 0.22-0.27). In the study sample, 19% of participants were iron deficient (n=210). Iron deficient participants had blood cadmium concentrations that were 51% higher than those who were not iron deficient (95% CI: 39%, 64%). CONCLUSIONS:Our data suggest that iron deficiency increases cadmium body burden. The observed association aligns with our previous finding that heavy menstrual bleeding, a substantial contributor to iron deficiency, was associated with higher blood cadmium concentrations in this cohort. KEYWORDS: Heavy metals, Female, Epidemiology

Inflammation Mediates the Relationship Between BMI and Serum Ferritin Among Women With Normal to High BMI in Azerbaijan but Not Malawi: BRINDA Project

ObjectivesConsidering the known metabolic relationships between adiposity, inflammation, and iron status, we examined whether inflammation mediates the relationship between BMI and serum ferritin (SF) concentration among women of reproductive age (15–49 years) with normal to high BMI in a low-income country (Malawi) and an upper-middle income country (Azerbaijan). MethodsCross-sectional survey data were analyzed from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project. Women with underweight (BMI <18.5 kg/m2), pregnancy, or a positive malaria test were excluded (total for analysis: Malawi, n = 594; Azerbaijan, n = 2528). Descriptive statistics were calculated to determine the proportion of women with overweight/obesity (OwOb, BMI ≥ 25 kg/m2), any inflammation (C-reactive protein [CRP] >5 μg/L or α-1-acid glycoprotein [AGP] >1 g/L), and iron deficiency (inflammation-adjusted SF < 15 μg/L). The relationship between BMI and unadjusted SF concentration and potential mediation by CRP and AGP was assessed separately in each country via structural equation modeling procedures, accounting for the complex survey designs. ResultsIn Malawi, the proportion of women with OwOb was 16%, inflammation 12%, and inflammation-adjusted iron deficiency 14% (12% unadjusted). In Azerbaijan, the proportions were: 57%, 35%, and 45% (31% unadjusted), respectively. In Malawi, BMI was not associated with SF concentration (P = 0.65). In Azerbaijan, a 1-unit increase in BMI was associated with a 3.3% (95% CI: 2.5, 4.3) increase in SF concentration. Approximately 61% of this relationship was mediated by CRP and AGP, of which 46% was via CRP and 15% via AGP. ConclusionsIron status is commonly adjusted for inflammation in populations with high expected burden of undernutrition and infectious disease. Considering that obesity is a source of inflammation, these data suggest that measurement and adjustment for inflammation may improve assessment of iron status in populations in which OwOb is common. Funding SourcesBill & Melinda Gates Foundation, Centers for Disease Control and Prevention, Eunice Kennedy Shriver National Institute of Child Health and Human Development, HarvestPlus, and the United States Agency for International Development.

Associations between Zinc and Hemoglobin Concentrations in Preschool Children and Women of Reproductive Age: An Analysis of Representative Survey Data from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) Project

BackgroundAnemia is a worldwide concern. Nutritional deficiencies and inflammation are considered main contributors, but zinc deficiency has only recently been associated with anemia. ObjectivesIn this study we assessed associations between zinc status and hemoglobin (Hb) concentrations and anemia in preschool children 6–59 mo old (PSC) and nonpregnant women of reproductive age 15–49 y old (WRA) in population-based nutrition surveys. MethodsCross-sectional data from 13 (PSC) and 12 (WRA) countries within the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project were used. Multivariable linear models were constructed that included zinc status (plasma/serum zinc concentrations), Hb concentrations and anemia, iron status, age, sex, and inflammation (C-reactive protein and α-1-acid glycoprotein). Zinc was adjusted for inflammation in PSC according to the BRINDA algorithm. ResultsData were available for 18,658 PSC and 22,633 WRA. Prevalence of anemia ranged from 7.5% to 73.7% and from 11.5% to 94.7% in PSC and WRA, respectively. Prevalence of zinc deficiency ranged from 9.2% to 78.4% in PSC and from 9.8% to 84.7% in WRA, with prevalence of zinc deficiency >20% in all countries except Azerbaijan (PSC), Ecuador (PSC), and the United Kingdom (WRA). Multivariable linear regression models showed that zinc concentrations were independently and positively associated with Hb concentrations in 7 of 13 countries for PSC and 5 of 12 countries for WRA. In the same models, ferritin concentration was also significantly associated with Hb among PSC and WRA in 9 and 10 countries, respectively. Zinc deficiency was significantly associated with anemia in PSC and WRA in 5 and 4 countries respectively. ConclusionsZinc deficiency was prevalent in most countries and associations between zinc and Hb in roughly half of the countries examined suggesting that strategies to combat zinc deficiency may help reduce anemia prevalence. More research on mechanisms by which zinc deficiency is associated with anemia and the reasons for the heterogeneity among countries is warranted.

Re-Defining the Population-Specific Cut-Off Mark for Vitamin A Deficiency in Pre-School Children of Malawi.

Retinol Binding Protein (RBP) is responsible for the transport of serum retinol (SR) to target tissue in the body. Since RBP is relatively easy and cheap to measure, it is widely used in national Micronutrient Surveys (MNS) as a proxy for SR to determine vitamin A status. By regressing RBP concentration against SR concentration measured in a subset of the survey population, one can define a population-specific threshold concentration of RBP that indicates vitamin A deficiency (VAD). However, the relationship between RBP and SR concentrations is affected by various factors including inflammation. This study, therefore, aimed to re-define the population-specific cut-off for VAD by examining the influence of inflammation on RBP and SR, among pre-school children (PSC) from the 2015–16 Malawi MNS. The initial association between RBP and SR concentrations was poor, and this remained the case despite applying various methods to correct for inflammation. The World Health Organization (WHO) recommends the threshold of 0.7 µmol/L to define VAD for SR concentrations. Applying this threshold to the RBP concentrations gave a VAD prevalence of 24%, which reduced to 10% after inflammation adjustments following methods developed by the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA). Further research is required to identify why SR and RBP were poorly associated in this population. Future MNS will need to account for the effect of inflammation on RBP to measure the prevalence of VAD in Malawi.

Inflammation correction in micronutrient deficiency with censored inflammatory biomarkers

Biomarkers of micronutrient status vary with inflammation, and can be corrected by a regression-based approach [Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA)] using measured concentrations of inflammation biomarkers, e.g., C-reactive protein (CRP) and/or α1-acid-glycoprotein (AGP). However, this is confounded when inflammation is measured with multiple assays with variable limits of detection (LOD) and lower limits of quantification (LLOQ). We aimed to develop a probability approach for the estimation of prevalence of micronutrient deficiency using the distribution of true serum/plasma micronutrient concentrations in the population. Left-censoring of an inflammation biomarker due to varying values of LOD or LLOQ was addressed by estimating the distribution of the inflammation biomarker at concentrations lower than the LOD and using this for the probability estimation of prevalence of nutrient deficiency. This method was evaluated using 2 publicly available data sets for children<5 y old: BRINDA and the Indian Comprehensive National Nutrition Survey. Each data set included measures of serum ferritin (SF), vitamin A, zinc, and CRP measured using different assays with variable LLOQs. The empirical distribution of SF after correction for CRP and AGP by the BRINDA method was comparable with the estimated probability distribution of SF, yielding similar estimates of iron deficiency prevalence when evaluated in the BRINDA data (17.4%; 95% CI: 15.2%, 19.7% compared with 16.8%; 95% CI: 13.9%, 20.0%; BRINDA compared with the probability method). The BRINDA method-adjusted iron deficiency prevalence was linearly associated with the proportion of left-censored CRP data, whereas these were not associated in the probability method. In the Indian survey data, estimates of prevalence of iron and zinc deficiency were comparable but vitamin A deficiency was lower by the probability method (17.6%; 95% CI: 16.7%, 20.2% compared with 15.7%; 95% CI: 15.2%, 16.3%; BRINDA compared with the probability method). The proposed probability method is a robust alternate approach to the estimation of the prevalence of nutrient deficiency with left-censored inflammation biomarker data.

Adjusting iron and vitamin A status in settings of inflammation: a sensitivity analysis of the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) approach

ABSTRACTBackgroundAccurate assessment of iron and vitamin A status is needed to inform public health decisions, but most population-level iron and vitamin A biomarkers are independently influenced by inflammation.ObjectivesWe aimed to assess the reproducibility of the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) regression approach to adjust iron [ferritin, soluble transferrin receptor (sTfR)] and vitamin A [retinol-binding protein (RBP), retinol] biomarkers for inflammation (α-1-acid glycoprotein and C-reactive protein).MethodsWe conducted a sensitivity analysis comparing unadjusted and adjusted estimates of iron and vitamin A deficiency using the internal-survey regression approach from BRINDA phase 1 (16 surveys in children, 10 surveys in women) and 13 additional surveys for children and women (BRINDA phase 2).ResultsThe relations between inflammation and iron or vitamin A biomarkers were statistically significant except for vitamin A biomarkers in women. Heterogeneity of the regression coefficients across surveys was high. Among children, internal-survey adjustments increased the estimated prevalence of depleted iron stores (ferritin <12 µg/L) by a median of 11 percentage points (pp) (24 pp and 9 pp in BRINDA phase 1 and phase 2, respectively), whereas estimates of iron-deficient erythropoiesis (sTfR >8.3 mg/L) decreased by a median of 15 pp (15 pp and 20 pp in BRINDA phase 1 and phase 2, respectively). Vitamin A deficiency (RBP <0.7 µmol/L or retinol <0.7 µmol/L) decreased by a median of 14 pp (18 pp and 8 pp in BRINDA phase 1 and phase 2, respectively) in children. Adjustment for inflammation in women resulted in smaller differences in estimated iron deficiency than in children.ConclusionsOur findings are consistent with previous BRINDA conclusions that not accounting for inflammation may result in an underestimation of iron deficiency and overestimation of vitamin A deficiency. Research is needed to understand the etiology of the heterogeneity in the regression coefficients before a meta-analyzed regression correction can be considered.

Association between anemia and household water source or sanitation in preschool children: the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

ABSTRACTBackgroundThe associations between anemia and household water source and sanitation remain unclear.ObjectivesWe aimed to assess the associations between anemia and household water source or sanitation in preschool children (PSC; age 6–59 mo) using population-based surveys from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project.MethodsWe analyzed national and subnational data from 21 surveys, representing 19 countries (n = 35,963). Observations with hemoglobin (Hb) and ≥1 variable reflecting household water source or sanitation were included. Anemia was defined as an altitude-adjusted Hb concentration <110 g/L. Household water source and sanitation variables were dichotomized as “improved” or “unimproved.” Poisson regressions with robust variance estimates were conducted for each survey, adjusting for child sex, age, household socioeconomic status, maternal education, and type of residence.ResultsAccess to an improved water source and improved sanitation ranged from 29.9% (Burkina Faso) to 98.4% (Bangladesh, 2012), and from 0.2% (Kenya, 2007) to 97.4% (Philippines), respectively. Prevalence of anemia ranged from 20.1% (Nicaragua) to 83.5% (Bangladesh, 2010). Seven surveys showed negative associations between anemia and improved sanitation. Three surveys showed association between anemia and improved water, with mixed directions. Meta-analyses suggested a protective association between improved household sanitation and anemia [adjusted prevalence ratio (aPR) = 0.88; 95% CI: 0.79, 0.98], and no association between improved household water and anemia (aPR = 1.00; 95% CI: 0.91, 1.10). There was heterogeneity across surveys for sanitation (P < 0.01; I2 = 66.3%) and water (P < 0.01; I2 = 55.8%).ConclusionsAlthough improved household sanitation was associated with reduced anemia prevalence in PSC in some surveys, this association was not consistent. Access to an improved water source in general had no association with anemia across surveys. Additional research could help clarify the heterogeneity between these conditions across countries to inform anemia reduction programs.

Inflammation Adjustment by Two Methods Decreases the Estimated Prevalence of Zinc Deficiency in Malawi.

Serum zinc concentration (SZC) is used widely to assess population-level zinc status. Its concentration decreases during inflammatory responses, which can affect the interpretation of the results. This study aimed to re-estimate the prevalence of zinc deficiency in Malawi based on the 2015–2016 Malawi Micronutrient Survey (MNS) data, by adjusting SZC measures with markers of inflammation. SZC and inflammation data from 2760 participants were analysed. Adjustments were made using: (1) The Internal Correction Factor (ICF) method which used geometric means, and (2) The Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) method, which used linear regression. Mean SZC values increased significantly when adjustments were made by either ICF or BRINDA (p < 0.001). The national prevalence of zinc deficiency decreased from 62% to 59%, after ICF adjustment, and to 52% after BRINDA adjustment. ICF and BRINDA values of SZC were highly correlated (p < 0.001, r = 0.99), but a Bland–Altman plot showed a lack of agreement between the two methods (bias of 2.07 µg/dL). There was no association between the adjusted SZC and stunting, which is a proxy indicator for zinc deficiency. Inflammation adjustment of SZC, using ICF or BRINDA, produces lower estimates of zinc deficiency prevalence, but the lack of agreement between the adjustment methods warrants further research. Furthermore, the lack of association between SZC and stunting highlights the need to explore other biomarkers and proxies of population zinc assessment. This study demonstrates the importance of considering inflammatory confounders when reporting SZC, to ensure accuracy and to support policy decision making.

Interpretation of vitamin B-12 and folate concentrations in population-based surveys does not require adjustment for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

ABSTRACTBackgroundVitamin B-12 and folate deficiencies in women and children have important public health implications. However, the evidence is conflicting and limited on whether the influence of inflammation on biomarker concentrations may be sufficiently and consistently influenced by inflammation to require adjustment for interpreting concentrations or estimating population prevalence of deficiencies.ObjectiveWe examined correlations between concentrations of the inflammation biomarkers C-reactive protein (CRP) and α1-acid glycoprotein (AGP) and serum vitamin B-12 and serum and RBC folate among nonpregnant women of reproductive age (WRA; 15–49 yr) and preschool children (PSC; 6–59 mo).MethodsWe analyzed cross-sectional data from 16 nationally representative nutrition surveys conducted in WRA (n = 32,588) and PSC (n = 8,256) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia project. Spearman correlations between CRP or AGP and vitamin B-12 or folate concentrations were examined, taking into account complex survey design effects.ResultsCorrelations between inflammation and vitamin B-12 or folate were weak, with no clear pattern of association in either WRA or PSC. Correlation coefficients between CRP and vitamin B-12 for WRA and PSC ranged from −0.25 to 0.16, and correlations between AGP and vitamin B-12 ranged between −0.07 and 0.14. Similarly, correlations between CRP and serum folate ranged from −0.13 to 0.08, and correlations between AGP and serum folate between −0.21 and 0.02. Only 3 surveys measured RBC folate, and among them, correlations for WRA ranged from −0.07 to 0.08 for CRP and −0.04 for AGP (1 country).ConclusionsBased on the weak and inconsistent correlations between CRP or AGP and vitamin B-12 or folate biomarkers, there is no rationale to adjust for inflammation when estimating population prevalence of vitamin B-12 or folate deficiencies in WRA or PSC.

Adjusting plasma or serum zinc concentrations for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

ABSTRACTBackgroundThe accurate estimation of zinc deficiency at the population level is important, as it guides the design, targeting, and evaluation of nutrition interventions. Plasma or serum zinc concentration (PZC) is recommended to estimate zinc nutritional status; however, concentrations may decrease in the presence of inflammation.ObjectivesWe aimed to assess the relation between PZC and inflammation in preschool children (PSC; 6–59 mo) and nonpregnant women of reproductive age (WRA; 15–49 y), and to compare different inflammation adjustment approaches, if adjustment is warranted.MethodsCross-sectional data from 13 nationally representative surveys (18,859 PSC, 22,695 WRA) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project were analyzed. Correlation and decile analyses were conducted, and the following 3 adjustment methods were compared if a consistent negative association between PZC and C-reactive protein (CRP) or α-1-acid glycoprotein (AGP) was observed: 1) exclude individuals with CRP > 5 mg/L or AGP > 1 g/L; 2) apply arithmetic correction factors; and 3) use the BRINDA regression correction (RC) approach.ResultsIn 6 of 12 PSC surveys, the estimated prevalence of zinc deficiency increased with increasing CRP deciles, and to a lesser extent, with increasing AGP deciles. In WRA, the association of PZC with CRP and AGP was weak and inconsistent. In the 6 PSC surveys in which adjustment methods were compared, application of RC reduced the estimated prevalence of zinc deficiency by a median of 11 (range: 4–18) percentage points, compared with the unadjusted prevalence.ConclusionsRelations between PZC and inflammatory markers were inconsistent, suggesting that correlation and decile analyses should be conducted before applying any inflammation adjustments. In populations of PSC that exhibit a significant negative association between PZC and CRP or AGP, application of the RC approach is supported. At this time, there is insufficient evidence to warrant inflammation adjustment in WRA.

Comparing hemoglobin distributions between population-based surveys matched by country and time

BackgroundValid measurement of hemoglobin is important for tracking and targeting interventions. This study compares hemoglobin distributions between surveys matched by country and time from The Demographic and Health Survey (DHS) Program and the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project.MethodsFour pairs of nationally representative surveys measuring hemoglobin using HemoCue® with capillary (DHS) or venous (BRINDA) blood were matched by country and time. Data included 17,719 children (6–59 months) and 21,594 non-pregnant women (15–49 y). Across paired surveys, we compared distributional statistics and anemia prevalence.ResultsSurveys from three of the four countries showed substantial differences in anemia estimates (9 to 31 percentage point differences) which were consistently lower in BRINDA compared to DHS (2 to 31 points for children, 1 to 16 points for women).ConclusionWe identify substantial differences in anemia estimates from surveys of similar populations. Further work is needed to identify the cause of these differences to improve the robustness of anemia estimates for comparing populations and tracking improvements over time.

Iron and Vitamin a Biomarkers in Mothers and Infants in Rural Uganda: Using the BRINDA Approach to Adjust for Inflammation (P10-108-19)

ObjectivesWe aimed to assess prevalence of iron and vitamin A deficiencies in Ugandan mothers and infants using the BRINDA (Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia) adjustment and to ascertain any differences by prevalence of malaria. MethodsFrom a prospective birth cohort (N = 5000) conducted in rural Uganda (2014–2016), samples from mothers (n = 1652, at birth) and infants (n = 695, 5–7 m/o) were analyzed for ferritin (FER), soluble transferrin receptor (sTFR), retinol binding protein (RBP), CRP, AGP, hemoglobin (Hb) and malaria. FER, sTFR and RBP were adjusted for inflammation using CRP and AGP. Depleted iron stores were defined as: FER <12 μg/L and <15 μg/L in children and mothers respectively; sTFR >8.3 mg/L for Fe-deficient erythropoiesis; RBP <1.05 μmol/L for vitamin A deficiency; and Hb <110 g/L for anemia. Prevalence estimates were stratified by malaria status. ResultsAdjustment for inflammation in mothers increased depleted iron stores (FER) from 7 to 12%, and decreased iron-deficient erythropoiesis (sTFR) from 27 to 22%. For children, adjustment increased depleted Fe stores from 17 to 40%, and iron-deficient erythropoiesis from 76 to 64%. Vitamin A deficiency in mothers was 9% and in infants decreased after adjustment (15% vs 4%). The prevalence of altitude adjusted anemia was 18% in mothers and 72% in infants. The prevalence of tissue iron deficiency (BIS <0 mg/kg) using adjusted sTFR and FER was 10% for mothers and 50% for infants compared to 8% and 34% using unadjusted markers respectively (Tables 1,2). Almost 14% of children (n = 75) were diagnosed with malaria. Malaria prevalence in mothers was low (5%), possibly due to the high (82%) prevalence of IPT prophylaxis reported during pregnancy. No significant differences were found in adjusted versus unadjusted estimates for Fe markers stratifying by malaria. ConclusionsFe deficiency adjusted estimates varied by biomarker and were not correlated with malaria in line with BRINDA recommendations. For mothers and children, the prevalence of Fe deficiency (sTFR) and anemia (Hb) were similar, suggesting that a big part of anemia in Uganda could be due to Fe deficiency as opposed to other micronutrients. Funding SourcesSupport provided by Feed the Future Innovation Lab for Nutrition, funded by the United States Agency for International Development (USAID). Supporting Tables, Images and/or Graphs▪▪

Evaluation of Hemoglobin Cutoffs for Defining Anemia in a Multinational Sample of Healthy Individuals: The BRINDA Project (OR07-07-19)

ObjectivesCurrent WHO hemoglobin (Hb) cutoffs (< 110 g/L, 6–59mo; < 120 g/L, 15–49y non-pregnant women) to define anemia were established in 1967 and validated in 1980 s among iron replete USA survey participants. Our objective was to examine the consistency of Hb cutoffs from multiple countries and age-variations in Hb concentrations among apparently healthy people using contemporary data. MethodsWe analyzed altitude and smoking (women only)-adjusted Hb data from 25 countries for preschool children (PSC, 6–59mo, 24 surveys, n = 35,088) and women of reproductive age (WRA, 15–49y, 20 surveys, n = 50,846) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project. Healthy was defined as: [ferritin >12 μg/L (< 5y), >15 μg/L (>5y)], RBP or retinol >0.7 μmol/L, CRP ≤ 5 mg/L or AGP ≤ g/L, and no malaria (if measured)]. We examined Hb levels, cut-offs at specified percentiles (%ile) and country variations with age-adjusted generalized mixed models using country as random intercept. ResultsThe final analytic sample was 41,314; the healthy inclusion criteria resulted in 17–88% data loss of the original data depending on country. Age and country-adjusted mean (SE) of Hb was 116.9 (1.44)g/L for PSC, and 129.1 (1.49)g/L for WRA and was significantly (P < 0.001) associated with age in PSC but not in WRA, and varied by country (pheterogeniety < .001, in each target group). Country explained 22% of the total Hb variance for each group. The pooled countries’ Hb at the 5%ile was 94 g/L for PSC [range: 79 g/L (Pakistan) - 113 g/L (USA], and 110 g/L for WRA [92 g/L (Nigeria) - 121 g/L (USA)]. ConclusionsThe high heterogeneity in Hb cutoffs among healthy people from different countries suggests that a single Hb cutoff for anemia may not work for every country. This multinational analysis suggests that different approaches may be warranted to establish Hb cutoffs. Funding SourcesBill & Melinda Gates Foundation.