General methodological aspects in the Brazilian National Survey on Child Nutrition (ENANI-2019): a population-based household survey

Abstract

This article aims to present general methodological aspects of the Brazilian National Survey on Child Nutrition (ENANI-2019), from the conception of the study design to details of the data collection. This is a household-based population survey with a sample calculated at 15,000 households to identify children under five years of age, conducted in 123 municipalities in Brazil’s 26 states and the Federal District. ENANI-2019 includes data on breastfeeding and dietary intake; anthropometric nutritional status of all children and their biological mothers; and nutritional status concerning the following micronutrients: iron (hemoglobin and ferritin), zinc, selenium, and vitamins A, B1, B6, B12, D, E, and folic acid of children from 6 to 59 months of age. A total of 193,212 households were visited, of which 19,951 were eligible, and 12,524 were included in the study. A total of 14,558 children were studied, of whom 13,990 (96.1%) and 13,921 (95.6%) had their body mass and length/stature measured, respectively, and 14,541 (99.9%) underwent 24-hour dietary recalls (24HR). Of the 12,598 children eligible for blood sample collection, 8,739 (69.3%) had at least one laboratory parameter measured. Data were collected from February 2019 to March 2020, when the survey was interrupted due to the COVID-19 pandemic. The evidence produced by the ENANI-2019 survey can back the formulation, follow-up, and/or reorientation of food and nutrition policies such as the promotion of breastfeeding and healthy eating and the prevention and control of different forms of malnutrition.

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

“…The obstacles faced with the partner laboratories included withdrawal by some from participating in the survey, requiring selection and training of a new laboratory with the study underway; and changes in the laboratories' routine, leading to fewer options for times to schedule household blood sample collection after the fieldwork had already begun. It was also challenging to collect data in areas with high rates of urban violence and in those in which fake news about the study circulated, spreading the idea that the blood sample collection aimed to transmit infectious diseases or that associated the interviewers with groups that kidnapped children or stole organs (more details in Alves-Santos et al 19 ).…”

“…The lessons from the study featured investing in communication with the local community and with society in general as a strategic element in the study 19 ; considering second sample collection as a relevant element in household surveys that include children; guaranteeing that the interviewer and phlebotomist worked together when the blood sample was drawn and that the child's identification number was recorded on both the interview form and the specimens, and providing a strategy for confirming the scheduled blood sample collection on the eve of the procedure.…”

“…Data were collected from March 2019 to March 2020, when the survey was interrupted due to the COVID-19 pandemic. Details on the study's communication strategies before and during data collection, the overall training, data collection stages, and the implications of the survey´s interruption for the ENANI-2019 sample are available in Alves-Santos et al 19 .…”

Sampling plan of the Brazilian National Survey on Child Nutrition (ENANI-2019): a population-based household survey

“…Therefore, the study population did not include: (1) children residing in collective households (hotels, boarding houses, orphanages, shelters, detention centers, barracks, hospitals, etc. ), improvised private households, and permanent private households without children; (2) indigenous children living in villages; (3) foreign children living in households where Portuguese was not spoken; and (4) children with conditions that prevented them from undergoing anthropometric measurement.…”

“…Data were collected after the child's parents or guardians signed two copies of the free and informed consent form. The methods used in the development of ENANI-2019 have been described in detail in specific publications 2,3,4,5 .…”