Methodological aspects of the micronutrient assessment in the <i>Brazilian National Survey on Child Nutrition</i> (ENANI-2019): a population-based household survey

Castro, Inês Rugani Ribeiro de; Normando, Paula; Alves-Santos, Nadya Helena; Bezerra, Flávia Fioruci; Citelli, Marta; Pedrosa, Lucia de Fatima Campos; Jordão Junior, Alceu Afonso; Lira, Pedro Israel Cabral de; Kurscheidt, Fábio Augusto; Silva, Paulo Ricardo Portella da; Salvatte, Keronlainy; Lacerda, Elisa Maria de Aquino; Anjos, Luiz Antonio dos; Boccolini, Cristiano Siqueira; Kac, Gilberto

doi:10.1590/0102-311X00301120

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THEMATIC SECTION: METHODOLOGICAL ASPECTS IN THE ENANI-2019 • Cad. Saúde Pública 3737 (88) • 2021 • https://doi.org/10.1590/0102-311X00301120 copy

Methodological aspects of the micronutrient assessment in the Brazilian National Survey on Child Nutrition (ENANI-2019): a population-based household survey

Aspectos metodológicos da avaliação de micronutrientes no Estudo Nacional de Alimentação e Nutrição Infantil (ENANI-2019): inquérito domiciliar de base populacional

Aspectos metodológicos de la evaluación de micronutrientes en el Estudio Nacional de Alimentación y Nutrición Infantil (ENANI-2019): encuesta domiciliaria de base poblacional

Authorship SCIMAGO INSTITUTIONS RANKINGS

This article aims to present methodological aspects on the collection, analyses, coverage, challenges, and the lessons learned from laboratory assessment of micronutrients on the Brazilian National Survey on Child Nutrition (ENANI-2019). This is a household survey on a probability sample of children under five years of age from 123 Brazilian municipalities in all 26 states and the Federal District. Blood samples were drawn by venipuncture at the homes of children 6 to 59 months of age. This procedure was performed by experienced phlebotomists from the laboratories located in the selected municipalities and scheduled in advance. Blood and serum levels were measured for biomarkers of nutritional status, using the services of a clinical test laboratory with nationwide coverage, for the following micronutrients: iron (hemoglobin and ferritin), zinc, selenium, folic acid, and vitamins A, B1, B6, B12, D, and E. C-reactive protein was analyzed as a marker of inflammation. A barcode identifier was used to track the blood samples and to link the biochemical test results to the other data collected in the survey. A total of 14,558 children were studied. Of the 12,598 eligible children, 8,829 (70.1%) had blood samples drawn. Of the total number of children who had samples drawn, 91.8% (n = 8,025) have results for at least nine of the 12 analyses performed. Coverage of the analysis varied from 95% (for vitamins A and E) to 84.2% (for folic acid). Aliquots of whole blood and serum were stored in a biorepository for future analyses. The results of this pioneering study in the country will back the formulation and, when necessary, the reorientation of public policies in food and nutrition.

Keywords:
Micronutrients; Infant; Preschool Child; Methods; Laboratory Test

Variables	Number of eligible children	Proportion of children with blood samples drawn (%)
Geographic region
North	2,362	84.0
Northeast	2,452	78.1
Southeast	2,726	64.5
South	2,380	56.1
Central West	2,768	68.6
Age group (months)
6-23	4,362	65.8
24-59	8,236	72.3
Total	12,598	70.1

Reason	Total (n = 3,769) *	6-23 months (n = 1,492)	24-59 months (n = 2,277)
%	%	%
Parent/guardian did not provide authorization	53.0	50.5	54.5
Operational problems with laboratory **	13.2	11.1	14.7
Difficulty performing venipuncture	10.0	15.5	6.3
Parent/guardian was not home or did not answer the door	8.6	8.7	8.5
Fieldwork interrupted due to COVID-19 pandemic	5.3	5.6	5.0
Child unavailable for procedure ***	3.1	2.1	3.7
Family moved	1.7	1.4	1.9
Urban violence	0.9	0.7	1.0
Others	2.1	2.7	2.0
Not reported by the interviewer	2.1	1.7	2.4

Analyses	Considering children eligible for blood sample collection			Considering children with blood samples collected
	Total (n = 12,598)	6-23 months (n = 4,362)	24-59 months (n = 8,236)	Total (n = 8,829)	6-23 months (n = 2,870)	24-59 months (n = 5,959)
	%	%	%	%	%	%
Complete blood count	65.0	60.2	67.5	92.7	91.5	93.3
Ferritin	64.7	58.9	67.8	92.4	89.5	93.7
C-reactive protein	65.0	59.6	67.9	92.8	90.5	93.9
Folic acid	59.0	52.1	62.7	84.2	79.2	86.6
Vitamin A	66.6	61.6	69.3	95.0	93.6	95.8
Vitamin B1	66.1	61.1	68.8	94.3	92.8	95.0
Vitamin B6	66.1	61.1	68.8	94.3	92.9	95.0
Vitamin B12	59.1	52.2	62.7	84.3	79.3	86.7
Vitamin D	65.2	59.8	68.1	93.1	90.8	94.1
Vitamin E	66.6	61.6	69.2	95.0	93.6	95.7
Zinc	63.9	57.6	67.2	91.2	87.5	92.9
Selenium	63.9	57.6	67.3	91.2	87.5	93.0

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[1] Correspondence
G. Kac Departamento de Nutrição Social e Aplicada, Instituto de Nutrição Josué de Castro, Universidade Federal do Rio de Janeiro. Av. Brigadeiro Trompowsky s/n, Bloco J, 2º andar, Rio de Janeiro, RJ 21941-590, Brasil. gilberto.kac@gmail.com