Paediatrics (RCH) - Theses
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ItemPrevalence, risk factors and outcomes of hearing loss in Australian children and adults: growing up in Australia’s child health CheckPoint study( 2019)Background Hearing loss of ageing is being reframed as a lifecourse problem with childhood origins. Supporting this theory, recent studies suggest a possible role of obesity, inflammation and telomere shortening in the pathogenesis of hearing loss in older adults. However, whether and when these associations emerge in populations is not known. Unlike clinical hearing loss requiring hearing aids and cochlear implantation, less is known about the outcomes of milder losses, which is a requisite for evidence-based hearing policy. Aims In 1485 child-parent dyads at child age 11-12 years, this thesis aimed to: 1) describe the current prevalence of hearing loss in Australian children and mid-life adults; 2) examine associations of obesity, inflammation and telomere length with hearing acuity in children and mid-life adults; 3) investigate child outcomes of slight-mild hearing loss. Methods Design & Participants: Children and parents in the national population-based cross-sectional Child Health CheckPoint sub-study nested within the Longitudinal Study of Australian Children (LSAC). LSAC recruited 5107 infants aged 3 to 19 months in 2004, following them across 8 biennial waves. Measures (all CheckPoint unless specified): Pure-tone audiometry; anthropometry (body mass index (BMI, kg/m2), fat/fat-free mass indices, waist-to-height ratio; LSAC waves 2-6 - BMI); plasma Glycoprotein A (GlycA, a biomarker of chronic inflammation); relative telomere length (T/S ratio); and child outcomes (health-related quality of life; academic and behavioural outcomes from LSAC wave 6). Analysis: We calculated prevalence of hearing loss with 95% Confidence Intervals (CIs). Linear/logistic regression quantified associations of body composition/trajectories (derived from latent class analysis), GlycA and telomere length with hearing threshold/loss. Linear regression quantified associations of hearing threshold/loss with outcomes. Results Aim 1: In children (n=1485, mean age 11.4 (standard deviation (SD) 0.5) years) and adults (n=1485, mean age 42.9 (SD 5.1) years), the prevalence of bilateral hearing loss >15 dB HL (slight or worse) was 9.3% and 27.3% respectively within speech frequencies. Prevalence in children rose substantively since 1990. Aim 2: Concurrent obesity, decade-long BMI trajectories and GlycA (but not telomere length) showed small associations with poorer hearing, particularly in lower frequencies. Associations evident by age 11-12 years were generally stronger in mid-life. Compared with those of normal weight, women with persistent severe obesity showed three times the odds of hearing loss. For every SD rise in GlycA, the odds of hearing loss rose by around 10% for children and 20% for adults. Aim 3: Scores of children with slight-mild bilateral hearing loss were 0.2-0.3 SD lower for sentence repetition, teacher-reported learning and physical PedsQL, but not other outcomes (e.g. receptive vocabulary, mathematical thinking, behaviour, psychosocial PedsQL). Conclusion Slight or worse hearing loss in childhood is prevalent and may be increasing. This may presage the profound later burden of age-related hearing loss. Like other age-related diseases, hearing loss may have adipose and inflammatory antecedents. Replication and mechanistic studies could inform causal inference and early prevention efforts. Slight-mild hearing loss showed small associations with some child outcomes; future research should investigate longitudinal and indirect effects, and the cost-benefit of identification and management strategies by age.