Cross-sectional study of the anthropometric characteristics of children with congenital Zika syndrome up to 12 months of life

Identifying biologically implausible values in big longitudinal data: an example applied to child growth data from the Brazilian food and nutrition surveillance system

BACKGROUND

Several strategies for identifying biologically implausible values in longitudinal anthropometric data have recently been proposed, but the suitability of these strategies for large population datasets needs to be better understood. This study evaluated the impact of removing population outliers and the additional value of identifying and removing longitudinal outliers on the trajectories of length/height and weight and on the prevalence of child growth indicators in a large longitudinal dataset of child growth data.

METHODS

Length/height and weight measurements of children aged 0 to 59 months from the Brazilian Food and Nutrition Surveillance System were analyzed. Population outliers were identified using z-scores from the World Health Organization (WHO) growth charts. After identifying and removing population outliers, residuals from linear mixed-effects models were used to flag longitudinal outliers. The following cutoffs for residuals were tested to flag those: -3/+3, -4/+4, -5/+5, -6/+6. The selected child growth indicators included length/height-for-age z-scores and weight-for-age z-scores, classified according to the WHO charts.

RESULTS

The dataset included 50,154,738 records from 10,775,496 children. Boys and girls had 5.74% and 5.31% of length/height and 5.19% and 4.74% of weight values flagged as population outliers, respectively. After removing those, the percentage of longitudinal outliers varied from 0.02% (<-6/>+6) to 1.47% (<-3/>+3) for length/height and from 0.07 to 1.44% for weight in boys. In girls, the percentage of longitudinal outliers varied from 0.01 to 1.50% for length/height and from 0.08 to 1.45% for weight. The initial removal of population outliers played the most substantial role in the growth trajectories as it was the first step in the cleaning process, while the additional removal of longitudinal outliers had lower influence on those, regardless of the cutoff adopted. The prevalence of the selected indicators were also affected by both population and longitudinal (to a lesser extent) outliers.

CONCLUSIONS

Although both population and longitudinal outliers can detect biologically implausible values in child growth data, removing population outliers seemed more relevant in this large administrative dataset, especially in calculating summary statistics. However, both types of outliers need to be identified and removed for the proper evaluation of trajectories.

Congenital Zika Syndrome and Disabilities of Feeding and Breastfeeding in Early Childhood: A Systematic Review

Background: The Zika virus outbreak has affected pregnant women and their infants. Affected infants develop microcephaly and other congenital malformations referred to as congenital Zika syndrome. The neurological manifestations of congenital Zika syndrome may result in some feeding disorders, including dysphagia, swallowing dysfunction and choking while feeding. The aim of this study was to assess the prevalence of feeding and breastfeeding difficulties in children with congenital Zika syndrome and to estimate the risk of developing feeding disabilities. Methods: We searched PubMed, Google Scholar and Scopus for studies published from 2017 to 2021. From the total of 360 papers, reviews, systematic reviews, meta-analyses and publications in languages other than English were excluded. Therefore, the final sample of our study consisted of 11 articles about the feeding/breastfeeding difficulties of infants and children with congenital Zika syndrome. Results: Infants and children with congenital Zika syndrome were likely to suffer from feeding difficulties at various levels, including breastfeeding. Dysphagia problems ranged from 17.9% to 70%, and nutritional and non-nutritive suckling of infants was also affected. Conclusions: In addition to continuing to investigate the neurodevelopment of affected children, future research should also focus on the severity of factors influencing the degree of dysphagia, as well as the impact of breastfeeding on the child’s overall development.

Congenital Zika Infection and the Risk of Neurodevelopmental, Neurological, and Urinary Track Disorders in Early Childhood. A Systematic Review

It was late 2015 when Northeast Brazil noticed a worrying increase in neonates born with microcephaly and other congenital malformations. These abnormalities, characterized by an abnormally small head and often neurological impairment and later termed Congenital Zika Syndrome, describe the severity of neurodevelopmental and nephrological outcomes in early childhood, and the implication of microcephaly at birth. The purpose of the study was to describe the neurodevelopmental outcomes in children exposed to Zika virus during fetal life, with and without microcephaly at birth. The systematic review included research studies about the neurodevelopmental outcomes with and without microcephaly, as well as nephrological outcomes in early childhood. We searched PubMed, Crossref, PsycINFO, Scopus, and Google Scholar publications and selected 19 research articles published from 2018 to 2021. Most studies have linked the severity of microcephaly in childbirth to the neurodevelopmental and urinary outcomes in early childhood. However, most children without microcephaly at birth develop typically, while others may be at risk for language impairment.