Latent class modelling of respiratory outcomes in a South African birth cohort
type: CreativeWork
description: Background & Purpose: Early life is a key period determining long-term health, particularly in low-income and middle-income countries (LMICs) where negative exposures are common. This thesis focuses on two key respiratory outcomes: childhood wheezing and lung function. It examines (1) the underlying heterogeneity of wheezing and lung function measurements through the derivation of latent phenotype classes and (2) the impact of early-life lower respiratory tract infections (LRTIs) and other predictors on wheezing and lung function. Methods: Data from the Drakenstein Child Health Study (DCHS) was used to critically evaluate various statistical approaches for identifying latent structures and modelling longitudinal trajectories, tracking 1143 children until school age. To identify wheezing phenotypes, partition around medoids (PAM) clustering tailored for longitudinal data, latent class analysis (LCA) and LCA with random effects were applied and evaluated. Lung function measurements were adjusted for height (as a proxy for body size) using a multiplicative model approach. Prior to employing latent class mixed effects models (LCMM) to identify latent classes in longitudinal lung function data, generalised additive models for location, scale, and shape (GAMLSS) and interrupted time series (ITS) approaches were used to model the impact of LRTIs and other risk factors on longitudinal trajectories. Well-established distributions were chosen within the GAMLSS framework to minimise overfitting and ensure robustness. Findings: PAM successfully identified four clinically distinct wheezing phenotypes: never, early transient, late-onset, and recurrent, outperforming LCA, which faced challenges with class separation. Random-effect LCA improved the modelling of recurrent wheezing trends but faced limitations with rare or sparse data patterns. While investigating phenotype-specific risk factors, cross-validation proved valuable to ensure the robustness and stability of variable sele…
abstract: Background & Purpose: Early life is a key period determining long-term health, particularly in low-income and middle-income countries (LMICs) where negative exposures are common. This thesis focuses on two key respiratory outcomes: childhood wheezing and lung function. It examines (1) the underlying heterogeneity of wheezing and lung function measurements through the derivation of latent phenotype classes and (2) the impact of early-life lower respiratory tract infections (LRTIs) and other predictors on wheezing and lung function. Methods: Data from the Drakenstein Child Health Study (DCHS) was used to critically evaluate various statistical approaches for identifying latent structures and modelling longitudinal trajectories, tracking 1143 children until school age. To identify wheezing phenotypes, partition around medoids (PAM) clustering tailored for longitudinal data, latent class analysis (LCA) and LCA with random effects were applied and evaluated. Lung function measurements were adjusted for height (as a proxy for body size) using a multiplicative model approach. Prior to employing latent class mixed effects models (LCMM) to identify latent classes in longitudinal lung function data, generalised additive models for location, scale, and shape (GAMLSS) and interrupted time series (ITS) approaches were used to model the impact of LRTIs and other risk factors on longitudinal trajectories. Well-established distributions were chosen within the GAMLSS framework to minimise overfitting and ensure robustness. Findings: PAM successfully identified four clinically distinct wheezing phenotypes: never, early transient, late-onset, and recurrent, outperforming LCA, which faced challenges with class separation. Random-effect LCA improved the modelling of recurrent wheezing trends but faced limitations with rare or sparse data patterns. While investigating phenotype-specific risk factors, cross-validation proved valuable to ensure the robustness and stability of variable sele…
author: Mccready, Carlyle
language: en
keywords: Respiratory syncytial virus (RSV), Drakenstein Child Health Study (DCHS), partition around medoids (PAM), latent class analysis (LCA), latent class mixed effect models (LCMM), generalised additive models for location, scale and shape (GAMLSS), interrupted time series (ITS), lower respiratory tract infections (LRTI)
date published: 2025
date modified: 2026-07-22T22:23:22Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Statistical Sciences

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/42486