This epidemiological thesis firstly reviews the disease Multiple Sclerosis (MS): its history, pathology, clinical expression, and the current views on immunopathogenesis, aetiology and treatment. A separate review on ultraviolet radiation (UVR) and MS indicates that recent work in photoimmunology provides evidence that UVR can attenuate T helper 1 cell mediated processes through several mechanisms, and that epidemiological features of MS, such as the striking latitudinal gradient and seasonal variation in month of birth, MS onset and disease activity, are at least in part consistent with the hypothesis that UVR exposure may reduce the risk of MS. An ecological analysis was conducted as part of the PhD to demonstrate that regional variation in MS prevalence in the continent of Australia could be closely predicted by regional UVR levels, but analytical epidemiological studies are required to further investigate the UVR hypothesis. The project central to this thesis was a population based case-control study on Multiple Sclerosis, conducted in Tasmania, Australia. It examined: (i) whether high past sun exposure was associated with a reduced risk of MS, (ii) whether sibship structure and past infections influenced the risk of MS and (iii) whether having had children and differences in prevalence and strength of MS risk factors between men and women could explain the sex difference in MS. Interviews were conducted with 136 cases with MS and 272 controls randomly drawn from the community and matched on sex and birth year. In one of the methodology chapters, a measure-retest and method comparison was conducted to examine aspects of reliability of the sun exposure measures used in the case-control study. A separate study on 104 healthy volunteers was carried out to examine the effect of seasonal variation and body hair on melanin density estimates based on skin reflectance. The case-control study showed that higher past sun exposure, particularly during childhood and early adolescence, was associated with a reduced risk of MS, which is compatible with UVR having a protective role against MS. Having younger siblings, but not older siblings, was also associated with a reduced risk of MS, while having had glandular fever or having high antibody titers against the Epstein-Barr virus was associated with an increased risk of MS. Among women, a negative association was found between having had children and MS. The finding of an inverse association between sun exposure during childhood and early adolescence and MS, if confirmed in future work, will have important public health implications.

No description available.

No description available.

The research presented in this thesis arose out of work done by the Māori Asthma Review (Pomare et al, 1991). The Māori Asthma Review was undertaken because of concern regarding the excessive number of deaths and hospitalisations from asthma among Māori people, even though evidence at that time, was that asthma prevalence was similar between Māori and non-Māori children. One of the key findings from the review was that there were a combination of barriers for Māori when accessing asthma services, which were almost certainly reflected in more severe asthma and higher hospital admission rates. This thesis has involved conducting three pieces of new research: (i) a series of reviews and analyses of descriptive data on asthma prevalence, hospitalisations and mortality in Māori and non-Māori; (ii) analyses of the ethnicity data from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III Wellington survey; and (iii) a follow-up study of Māori adolescents with asthma examining factors affecting asthma severity, access to health care and asthma quality of life in this adolescent population. The mortality analyses showed that Māori were disproportionately affected by the asthma epidemics during the 1960s and 1970s and that while the asthma mortality rates have declined now, they remain higher in Māori than in non-Māori. Asthma hospitalisation rates continue to be higher in Māori compared to non-Māori across all age groups. Hospital admission rates are generally higher in rural areas for Māori whereas those for non-Māori are higher in urban areas. Analyses of the ISAAC Phase III data show that Māori children are experiencing both greater asthma symptom prevalence and increased asthma severity compared with non-Māori children and that this is not explained by risk factors such as smoking. In the follow-up study of Māori adolescents, baseline asthma severity and frequency of wheeze were important determinants of subsequent morbidity. Having an asthma action plan, a peak flow meter and having routine visits to the general practitioner were all associated with small improvements in asthma quality of life during the one year follow-up. The only significant predictor of access problems during the one year follow-up was having had access problems at baseline. Cost was the most significant barrier to accessing care for these families. Asthma continues to be a significant health problem for Māori. The research conducted for this thesis supports and extends previous research indicating that asthma is more severe in Māori, because of problems of access to health care. It also indicates that differences in asthma prevalence between Māori and non-Māori are now being seen in children as well as adults, and that management and treatment issues underlie the emerging increase in asthma prevalence among Māori. Attention to access issues across mainstream health structures along with support for Māori provider organisations should continue. Additonally, active approaches to monitor differential treatment and barriers to effective interventions are needed.

Parkinson’s disease (PD) is a progressive, degenerative, neurological disease. The progressive disability associated with PD results in substantial burdens for those with the condition, their families and society in terms of increased health resource use, earnings loss of affected individuals and family caregivers, poorer quality of life, caregiver burden, disrupted family relationships, decreased social and leisure activities, and deteriorating emotional well-being. Currently, no cure is available and the efficacy of available treatments, such as medication and surgical interventions, decreases with longer duration of the disease. Whilst the cause of PD is unknown, genetic and environmental factors are believed to contribute to its aetiology. Descriptive and analytical epidemiological studies have been conducted in a number of countries in an effort to elucidate the cause, or causes, of PD. Rural residency, farming, well water consumption, pesticide exposure, metals and solvents have been implicated as potential risk factors for PD in some previous epidemiological studies. However, there is substantial disagreement between the results of existing studies. Therefore, the role of environmental exposures in the aetiology of PD remains unclear. The main component of this thesis consists of a case-control study that assessed the contribution of environmental exposures to the risk of developing PD. An existing, previously unanalysed, dataset from a local case-control study was analysed to inform the design of the new case-control study. The analysis results suggested that regular exposure to pesticides and head injury were important risk factors for PD. However, due to the substantial limitations of this existing study, further confirmation of these results was desirable with a more robustly designed epidemiological study. A new exposure measurement instrument (a structured interviewer-delivered questionnaire) was developed for the new case-control study to obtain data on demographic, lifestyle, environmental and medical factors. Prior to its use in the case-control study, the questionnaire was assessed for test-retest repeatability in a series of 32 PD cases and 29 healthy sex-, age- and residential suburb-matched electoral roll controls. High repeatability was demonstrated for lifestyle exposures, such as smoking and coffee/tea consumption (kappas 0.70-1.00). The majority of environmental exposures, including use of pesticides, solvents and exposure to metal dusts and fumes, also showed high repeatability (kappas >0.78). A consecutive series of 163 PD case participants was recruited from a neurology clinic in Brisbane. One hundred and fifty-one (151) control participants were randomly selected from the Australian Commonwealth Electoral Roll and individually matched to the PD cases on age (± 2 years), sex and current residential suburb. Participants ranged in age from 40-89 years (mean age 67 years). Exposure data were collected in face-to-face interviews. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression for matched sets in SAS version 9.1. Consistent with previous studies, ever having been a regular smoker or coffee drinker was inversely associated with PD with dose-response relationships evident for packyears smoked and number of cups of coffee drunk per day. Passive smoking from ever having lived with a smoker or worked in a smoky workplace was also inversely related to PD. Ever having been a regular tea drinker was associated with decreased odds of PD. Hobby gardening was inversely associated with PD. However, use of fungicides in the home garden or occupationally was associated with increased odds of PD. Exposure to welding fumes, cleaning solvents, or thinners occupationally was associated with increased odds of PD. Ever having resided in a rural or remote area was inversely associated with PD. Ever having resided on a farm was only associated with moderately increased odds of PD. Whilst the current study’s results suggest that environmental exposures on their own are only modest contributors to overall PD risk, the possibility that interaction with genetic factors may additively or synergistically increase risk should be considered. The results of this research support the theory that PD has a multifactorial aetiology and that environmental exposures are some of a number of factors to contribute to PD risk. There was also evidence of interaction between some factors (eg smoking and welding) to moderate PD risk.

No description available.

No description available.

In this thesis, I describe a series of studies of the prevalence, causes, and management of asthma in the Pacific. The core study of the thesis is Phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). The ISAAC study is the largest worldwide epidemiological study on asthma prevalence and was established partly in response to the increases in asthma prevalence in most parts of the world over the last two to three decades. The ISAAC Phase I study found large variations in asthma prevalence globally, but no Pacific countries were involved. Thus, the situation in the Pacific was relatively unknown due to lack of standardised studies on prevalence and time trends. The burden and impact of other non-communicable diseases such as cardiovascular and other metabolic disorder on the other hand have been the target of various studies in the Pacific for the past few decades The ISAAC Phase III study was therefore conducted in eight Pacific countries to address the above issues, as well as to enhance Pacific participation and contribution to international research on the causes and control of asthma. The collaboration also served the purpose of encouraging and strengthening health research capacity in the Pacific. The ISAAC Phase III study was followed by an asthma self-management intervention trial conducted in Tonga by the ISAAC Tonga study team. Methods The work presented in this thesis involved: (i) the conduct of the ISAAC Phase III study in the six Pacific islands of Tokelau, Samoa, Fiji Islands, Tonga, Niue and the Cook Islands, as well as the incorporation into the analysis of data that had already been collected in French Polynesia and New Caledonia; (ii) analysis of the data from an environmental asthma risk factor questionnaire which was included in the ISAAC survey in three countries (Samoa, Fiji and Tokelau); (iii) the conduct of the Tonga Asthma Self-management Study which was intended to assess whether the introduction of asthma education, including asthma self-management plans, would reduce morbidity from asthma. Results A total of 20,876 13-14 year olds, in the eight countries involved, participated in the ISAAC Phase III survey, with an overall response rate of 92%. The survey showed that there was considerable variation in the prevalence of asthma symptoms between the eight countries, ranging from 5.8% for current wheeze in Samoa to 16.2% in Tonga. Tokelau reported the highest prevalence (19.7%) for current wheeze, but the number of participants was relatively small. The prevalences of asthma symptoms among Pacific children in the Pacific were lower than those reported for Pacific, Māori and European children living in New Zealand from a previous study (ISAAC Phase I) conducted ten years earlier using the same methodology. The prevalence of 'asthma ever' in Pacific children living in the Pacific was also lower than that found among Pacific, Māaori and European children in New Zealand. The ISAAC Phase III environmental questionnaire data was collected in Samoa, Fiji and Tokelau. The analyses indicated that the major factors associated with current wheeze (across the three countries) were paracetamol use in the previous year (odds ratio (OR) = 1.36, 95% CI 1 15-1.61), the use of open fires for cooking (OR = 1.34,95% CI 1.13-1.58), lack of physical activity as indicated by television viewing more than 3 hours per day (OR = 1.24,95% CI 1.04-1.47), regular meat consumption (OR = 1.30,95% CI 1.09-1.54) and regular cereal consumption (OR = 1.29,95% CI 1.07-1.54). However, these risk factors were not particular strong, and did not account for a large proportion of asthma cases (i.e. they had relatively low population attributable risks). The asthma self-management plan intervention study resulted in significant improvements in asthma morbidity and the management of asthma among individuals and the service provision. The success of the introduction of the self-management plan, in the context of an asthma clinic, was reflected by improvement in measures of asthma morbidity, such as peak expiratory flow rates and nights woken with asthma or coughing. There was also a reduction in the requirement for acute medical treatment, indicated by a decrease in emergency department hospital visits for asthma and hospital admissions. The programme was so successful that the intervention study evolved into a full regular asthma clinic for the main island of Tonga. It is now intended that the asthma self-management programme will be extended throughout the rest of Tonga, through the primary health care system. Conclusions The ISAAC Phase IIII survey has shown that, although there is a significant level of morbidity, asthma prevalence in Pacific countries is lower than those among Pacific people in New Zealand. Together with the large variations in prevalence between the six Pacific countries that participated, this further lends support for the role of environmental risk factors in asthma. The availability of data on eight countries using a standardised methodology also provides useful information on the burden of asthma in the Pacific that is comparable to other countries regionally and internationally as well as forming a basis for ascertaining trends in the future. The crucial role of asthma self-management plans in asthma management is supported by the findings of the Tonga study, and its implementation is essential in the resource-scarce Pacific health setting. The collaborative nature of ISAAC in the Pacific has further raised awareness of the need for capacity building and creating networks and environments that enhance health research in areas other than asthma. The study has also nurtured an environment and network that encourages and strengthens the establishment of health research as one of the vital tools for achieving better health.

No description available.

Parkinson’s disease (PD) is a progressive, degenerative, neurological disease. The progressive disability associated with PD results in substantial burdens for those with the condition, their families and society in terms of increased health resource use, earnings loss of affected individuals and family caregivers, poorer quality of life, caregiver burden, disrupted family relationships, decreased social and leisure activities, and deteriorating emotional well-being. Currently, no cure is available and the efficacy of available treatments, such as medication and surgical interventions, decreases with longer duration of the disease. Whilst the cause of PD is unknown, genetic and environmental factors are believed to contribute to its aetiology. Descriptive and analytical epidemiological studies have been conducted in a number of countries in an effort to elucidate the cause, or causes, of PD. Rural residency, farming, well water consumption, pesticide exposure, metals and solvents have been implicated as potential risk factors for PD in some previous epidemiological studies. However, there is substantial disagreement between the results of existing studies. Therefore, the role of environmental exposures in the aetiology of PD remains unclear. The main component of this thesis consists of a case-control study that assessed the contribution of environmental exposures to the risk of developing PD. An existing, previously unanalysed, dataset from a local case-control study was analysed to inform the design of the new case-control study. The analysis results suggested that regular exposure to pesticides and head injury were important risk factors for PD. However, due to the substantial limitations of this existing study, further confirmation of these results was desirable with a more robustly designed epidemiological study. A new exposure measurement instrument (a structured interviewer-delivered questionnaire) was developed for the new case-control study to obtain data on demographic, lifestyle, environmental and medical factors. Prior to its use in the case-control study, the questionnaire was assessed for test-retest repeatability in a series of 32 PD cases and 29 healthy sex-, age- and residential suburb-matched electoral roll controls. High repeatability was demonstrated for lifestyle exposures, such as smoking and coffee/tea consumption (kappas 0.70-1.00). The majority of environmental exposures, including use of pesticides, solvents and exposure to metal dusts and fumes, also showed high repeatability (kappas >0.78). A consecutive series of 163 PD case participants was recruited from a neurology clinic in Brisbane. One hundred and fifty-one (151) control participants were randomly selected from the Australian Commonwealth Electoral Roll and individually matched to the PD cases on age (± 2 years), sex and current residential suburb. Participants ranged in age from 40-89 years (mean age 67 years). Exposure data were collected in face-to-face interviews. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression for matched sets in SAS version 9.1. Consistent with previous studies, ever having been a regular smoker or coffee drinker was inversely associated with PD with dose-response relationships evident for packyears smoked and number of cups of coffee drunk per day. Passive smoking from ever having lived with a smoker or worked in a smoky workplace was also inversely related to PD. Ever having been a regular tea drinker was associated with decreased odds of PD. Hobby gardening was inversely associated with PD. However, use of fungicides in the home garden or occupationally was associated with increased odds of PD. Exposure to welding fumes, cleaning solvents, or thinners occupationally was associated with increased odds of PD. Ever having resided in a rural or remote area was inversely associated with PD. Ever having resided on a farm was only associated with moderately increased odds of PD. Whilst the current study’s results suggest that environmental exposures on their own are only modest contributors to overall PD risk, the possibility that interaction with genetic factors may additively or synergistically increase risk should be considered. The results of this research support the theory that PD has a multifactorial aetiology and that environmental exposures are some of a number of factors to contribute to PD risk. There was also evidence of interaction between some factors (eg smoking and welding) to moderate PD risk.