Skip to content
|City||Sydney, New South Wales|
|University||University of Sydney|
|Thesis type||Doctor of Philosophy|
The link between ill-health has been appreciated for some time. The extremely high rates of persistent and sever otitis media, rhinosinusitis and bronchitis seen in rural and remote Aboriginal children are another striking illustration. Previous research by the Menzies school of Health Research has indicated that, in the case of otitis media, disease begins in the first few weeks of life and that the impact of poverty is mediated through early and heavy colonisation of the nasopharynx with potential respiratory pathogens. This is consistent with data from other populations with high rates of respiratory bacterial disease.
The role of medical care and medical research in improving health outcomes for rural and remote Aboriginal children has a controversial history. Most of the debate revolves around the importance of medical care given in the underlying socioeconomic causes of disease, and whether medical researchers have benefited at the expense of their Aboriginal participants. Chapters 2 and 3 present the theoretical reasons why improved medical care could have enormous health benefits in this population, but advises that maximum benefit will only be achieved if there is a commitment to more applied clinical research. The systematic review of randomised controlled trials addressing the Aboriginal health problems (Chapter 4) shows that Aboriginal Australians are disadvantaged by the lack of well designed clinical research. While not addressing the motives and intentions of the research community, it supports the need to orientate researchers toward intervention studies.
Chapters 5 and 6 continue with the "evidence-based medicine" theme and suggest potential area where medical practice might be improved. A comprehensive and explicit review of the available medical literature is used to address the following clinical issues: 1) clarification of the diagnostic criteria; 2) the anticipated prognosis 3) provision of effective therapy. These systematic reviews emphasise the lack of research evidence addressing many fundamental aspects of clinical care for respiratory mucosal infections in rural and remote Aboriginal children.
Chapter 7 provides the first description of the diagnostic features of otitis media, rhinosinusitis and bronchitits for infants living in a remote Aboriginal community. For otitis media, asymptomatic bulging of the tympanic membrane is the best predictor of subsequent disease. The differences in clinical presentation compared with other populations emphasise the need for local data when the generalisability of research evidence is questioned. The concept of "pus producing" infections appears to be useful in distinguishing low-risk from very high-risk groups. A study examining the consistency of diagnosis using video images of pneumatic otoscopy identified considerable variability between six independent experts. The analysis suggests that even experts may underestimate the severity of disease in high-risk populations. Chapter 8 contributes to the unique longitudinal data already collected by the Menzies School of Health Research. Children enrolled in the first published prospective study involving remote Aboriginal children documented frequent attendances at the local health clinic (on average 38 by 1 year of age). "Sick" visits are most commonly for respiratory tract infections (5 per year), skin infections (2 per year), and diarrhoea (2 per year). Infants rarely present with ear infections. Failure to thrive also affects more than 50% of infants but is rarely described until the child is malnourished.
Chapter 8 also describes the changes in tympanic membrane appearance over time. The persistence of suppurative disease, even within a randomised controlled trial where 50% of infants are receiving long term antibiotic therapy and additional antibiotic use is common, is remarkable. Most severe disease starts in the first 18 months of life and improvement prior to 5 years of age is unusual. A study of school children conducted in another otitis-prone community documents that there are a small portion of children who change "ear states" over a four to six month period. However, this could result in considerable differences over longer periods, especially considering the relative lack of medical interventions applied within this age group.
Chapter 9 describes the available data from 2 randomised controlled trials of antibiotic. In COMIT 1 (Chronic Otitis Media Intervention Trial 1), children are randomised to amoxycillin or placebo when asymptomatic OME is present and this continues for up to 6 months. Fifty children have completed the study (required sample size of 120) but the results already have important implications for clinical practice. Only one child had aerated middle ears at the completion of the study. Antibiotics appear to have a limited effect on OME even in high risk populations. However, there has been a dramatic improvement in rates of AOM and perforation in infants within the community. It is not clear whether this is due to this research program, or other factors. The advantages of the randomised design in assessing specific interventions in these circumstances are clear.
In COMIT 2 children with CSOM were treated with standard therapy (topical framycetin-gramicidin-dexamethasone drops) and randomised to high or low compliance strategies with or without amoxycillin. The effect of amoxycillin was measured by its impact on the amount of nasal discharge. Fifty children completed the study. After six weeks of intensive therapy, only 5% of ears were dry. This is considerably less than the cure rates usually reported in the literature. The effect of amoxycillin on nasal discharge was not statistically significant, but there was a trend toward improvement. If these children do represent important transmitters of infection then modest benefits are worth pursuing. Further work examining these issues is currently in progress.
In summary, systematic reviews and the original research in this thesis support the view that chronic suppurative respiratory disease is a vicious circle of inflammation which promotes a state of persistent bacterial infection. Affected individuals may be important transmitters of infection. Medical interventions able to limit either severity of disease or spread of infection have enormous implications for disadvantaged children throughout the world. For otitis media, suppurative disease first presents as an asymptomatic bulging tympanic membrane. This is a chronic condition hat rarely resolves spontaneously. The preliminary clinical trial results have described the potential benefits and limitations of antibiotic therapy. Further trials are urgently required if we are to maximise the impact of effective medical therapy in high risk populations.
Australian Indigenous HealthInfoNet abstract