Blood pressure and albuminuria among Australian children

Abstract

There is a progressive and substantial shift in the global burden of disease towards non-communicable diseases, of which high blood pressure is one of the most important. While the relationship between blood pressure and risk is a continuous one, modified by individual- and population-level risk factors, the term hypertension is often applied to denote a blood pressure threshold associated with increased mortality that might justify intervention. Hypertension is a lifecourse disease with risk-factors that begin in early life playing an important role in establishing adverse risk trajectories. Kidney disease is another important non-communicable disease with an increasing global and Australian prevalence. Hypertension and kidney disease are linked, each may lead or exacerbate the other, and both are associated with albuminuria. This thesis, by publication, examines the prevalence and correlates of hypertension and albuminuria among Australian children. Chapter 1 is an introduction, including aims and a thesis overview. Chapters 2 and 3 are narrative reviews of hypertension and proteinuria respectively. Chapters 4 to 6 examine the prevalence and correlates of hypertension among Australian children. Chapter 4 uses data from children participating in the Australian Health Survey, and was the first nationwide, population-based estimate of the prevalence of hypertension among Australian children. Chapter 5 is a sub-study of 657 children from the Study of Environment on Aboriginal Resilience and Child Health, which is investigating the health of urban Aboriginal Australian children. Chapter 6 re-visits the national prevalence of hypertension among Australian children using data from the Longitudinal Study of Australian Children at 10 to 12 years of age. This study included 7139 children and captured a wide range of known and possible factors associated with hypertension in children, allowing for a more detailed examination of the predictors of hypertension in this population. Chapters 7 and 8 examine the prevalence of albuminuria among Australian children, also using data from the Australian Health Survey and Longitudinal Study of Australian Children. Given the lack of previous population-based research, we focus on the prevalence of albuminuria using the most widely used threshold of an albumin-to-creatinine (ACR) > 3.4 mg/mmol. We also examine the distribution of the urine ACR and its components among children to examine the validity of this threshold. Chapter 9 is a methods paper reviewing the handling of missing data and modern statistical methods that minimise bias where data are missing, as is common among survey and longitudinal data, and applied to the studies presented. Chapter 10 is a summation of this body of work and explores potential directions for future research.