Constructing growth reference curves for a cohort of South African children

Childhood growth impacts the future welfare of an individual and ultimately the nation. The importance of childhood growth monitoring with growth curves that accurately represent the growth of the population of interest cannot be overemphasised. This dissertation sought to model the growth of a cohort of South African children and compare their growth to the World Health Organisation (WHO) 2006 Child Growth Standards. Growth reference curves were derived using parametric and semi-parametric methods within the Generalised Additive Models for Location, Scale and Shape (GAMLSS) framework. Various distributions for the growth measurements were compared as well as various curve smoothing approaches for the longitudinal profiles, including cubic splines, fractional polynomials and Berkey-Reed First and Second Order models. The preferred approach was to use the Box-Cox Power Exponential (BCPE) distribution with curve smoothing by cubic splines. Non-parametric quantile regression served as a confirmation that the chosen parametric distributions were appropriate for the data. A comparison of the derived growth references to the WHO (2006) standards revealed deviations in the patterns of growth and a greater likelihood of diagnosing a child as underweight, stunted or having micro- or macrocephaly when measured against the WHO standards. The poor socioeconomic status and associated harmful exposures of the cohort were noted as potential contributing factors. A fair comparison would require a reasonably healthy and representative sample of the South African population. These findings do however call into question the appropriateness of the WHO standards for measuring the growth of South African children and bring into focus the value of developing national growth standards.

Grantor

Department of Statistical Sciences

Year dc:date.issued

2022

Author dc:creator

• Ross, Melinda

Advisor dc:contributor.advisor

• Little, Francesca

• statistical sciences

Handle dc:identifier.uri

http://hdl.handle.net/11427/37751

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/37751