Melbourne School of Population and Global Health - Theses
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ItemEpidemiology of obstructive sleep apnoea: diagnosis, prevalence, comorbiditis, and risk factors( 2019)Obstructive sleep apnoea (OSA) occurs due to repetitive partial or complete upper airway obstruction during sleep and may lead to generalised hypoxia and/or arousals from sleep. OSA has both direct and indirect health and economic costs. However, design of public health interventions to control OSA is constrained by some critical gaps in knowledge. OSA is widely regarded to be highly prevalent but the reported prevalence estimates vary widely. The last population prevalence study in Australia was performed nearly twenty-five years ago. New estimates on population prevalence and the comorbidities associated with OSA would help better understand the burden of disease. Several OSA-screening questionnaires have been recommended for use in primary care settings in Australia, but these questionnaires have not been validated in the Australian primary-care population. Although OSA is seemingly associated with some chronic disorders such as cardiovascular and cerebrovascular disorders, metabolic disorders, respiratory disorders and psychiatric disorders, evidence for some associations are limited. Furthermore, the currently known modifiable risk factors for OSA are limited and rarely based on longitudinal evidence. No childhood risk factors are known for OSA. Given these knowledge gaps, during my doctoral work I aimed (1) to determine the validity of commonly known OSA-screening-questionnaires, (2) to describe the prevalence of OSA and its co-morbidities in the general population, and (3) to describe some potential early-life and lifetime risk factors for OSA. My specific objectives were (a) to systematically summarise the current evidence on the validity of the common OSA questionnaires for which such systematically synthesised evidence was unavailable, (b) to determine the validity of some common OSA-screening-questionnaires to detect OSA among middle-aged Australian adults, (c) to systematically summarise the available evidence on the prevalence of OSA in the adult general population including in age and sex- specific subgroups, (d) to describe the prevalence and associated chronic co-morbidities of OSA in middle-aged Australian adults, (e) to determine the role of lifetime lung function trajectories on OSA in adult life, and (f) to determine the role of childhood respiratory risk factors on OSA in adult life. To achieve the first aim, I systematically synthesised the literature on the validity of the Berlin questionnaire (Chapter 3). The evidence on the validity of the other questionnaires were already synthesised at the time I commenced this work. The included studies reported varied sensitivity and specificity based on the OSA assessment method used. I then used the data from the Tasmanian Longitudinal Health Study (TAHS) to validate the Berlin (BQ), STOP-Bang and OSA-50 questionnaires against type-4 sleep studies (Chapter 6). To determine if the flow-based AHI or ODI is more suitable as the reference standard, I investigated their agreement in detecting and classifying OSA (Chapter 6 [6.1]). I found that ODI identified more clinically significant OSA than flow-based AHI. Unlike in the previous studies that relied only on conventional AHI/ respiratory disturbance index (RDI)/oxygen desaturation index (ODI) cut-off levels for the reference test, I derived and used a new reference standard, namely, ‘clinically-relevant OSA’ that included moderate-severe OSA (ODI≥15) and mild (ODI≥5) OSA with symptoms as a combined group, as this is the group that needs to be captured for clinical management. I found that all three questionnaires were not clinically useful on their own (sub-optimal sensitivity and specificity) in a simulated primary-care sample but could be used to rule-in OSA (high specificity) when combined with Epworth sleepiness scale (Chapter 6 [6.2]). I also found that OSA-50 and STOP-Bang had a moderate sensitivity and low specificity and BQ had low sensitivity and moderate specificity, at the recommended thresholds, in the general population (Chapter 6 [6.3]). The trade-off between sensitivity and specificity remain a limitation of their practical use. To achieve the second aim, I systematically synthesised the literature on the prevalence of OSA (Chapter 4). I found that the prevalence of OSA varied between population subgroups and the OSA assessment methods. I then used the data from the Ten to Men study to determine the prevalence of doctor diagnosed OSA in Australian men and its co-morbidities (Chapter 7 [7.1]). I found that the prevalence increased from 2% in younger adults to 8% in the middle-age and that OSA was associated with several chronic cardiovascular, metabolic, respiratory and psychiatric disorders. Using data from the TAHS, I found the prevalence of medically-confirmed OSA to be 5% and probable OSA as determined by the STOP-Bang questionnaire to be 15% (Chapter 7 [7.2]). Medically-confirmed OSA as well as probable OSA were associated with several co-morbidities as seen in the Ten to Men study. Furthermore, I investigated how nocturnal-asthma-like symptoms and bronchial hyper-reactivity (BHR) contribute to the association between OSA-risk and current-asthma using the data from TAHS. I found no evidence for any role of BHR in this association but found some evidence for some nocturnal asthma symptoms to be suggestive of undiagnosed OSA. To achieve the third aim, I investigated how OSA is related to lifetime lung function trajectories and childhood respiratory risk factors using longitudinal data from the TAHS. I found that three trajectories were associated with both probable OSA (defined using STOP-Bang questionnaire) and medically-confirmed OSA (Chapter 8 [8.1]). Frequent childhood lower respiratory tract infection, asthma and lung function trajectories were associated with probable OSA (Chapter 8 [8.2]). Overall, my findings have significant public health, clinical and research implications and significantly advanced the current knowledge in this area. My assessment between ODI and flow-based AHI is the first such evidence and suggest that ODI should be preferred in clinical practice. Current OSA screening-questionnaires could be useful in epidemiological research but not as clinical tools. This calls for development of better screening methods. My findings challenge the current recommendations for OSA screening at primary-care and I make suggestions as to how this process could be improved. The high prevalence of OSA in general, and in males and elderly, and its association with other priority chronic disorders provide public health foci for interventions. The demonstrated role of nocturnal respiratory symptoms in the OSA-asthma association suggests the need for clinical vigilance for undiagnosed OSA in patients with nocturnal symptoms. Furthermore, the evidence for association of lung function trajectories and childhood risk factors with OSA advances the current knowledge and provides platforms for future research to delineate the seemingly complex pathophysiology and natural history of OSA.
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ItemHIV care decentralization in lower- and middle-income countries: outcomes, costs, and cost effectiveness( 2018)Decentralized provision of HIV care continuum – from diagnosis to chronic antiretroviral treatment (ART) – at primary health care facilities (PHCFs) is a critical step towards realizing optimal care coverage in national programs of lower- and middle-income countries (LMICs). Whether such a model of provision is justified depends on considerations of effectiveness, program costs, and cost-effectiveness. This research project aims to: a) examine the effectiveness of decentralized provision of HIV testing and counseling (HTC), pre-ART (ART initiation), and long-term ART care relative to hospital provision with the following outcomes: • Cascade of service receipt in HIV testing and counseling (HTC); • The timeliness of ART initiation by baseline CD4 count and clinical stage; • Treatment adherence during ART care. b) estimate and compare ART program costs of decentralized care at PHCFs and those of hospital care; c) estimate the cost-effectiveness of decentralized provision of routine, chronic ART care relative to hospital (centralized) provision. Data from national surveys and reviews of published studies in Indonesia and sub-Saharan Africa were analyzed using multivariate statistics, meta-analysis, and model-based cost-effectiveness analysis. In HTC, pregnant women were equally likely to receive a full HTC procedure, up to post-test counseling, at both hospitals and PHCFs in four high-prevalence countries (Lesotho, Malawi, Zambia, and Zimbabwe), with a positive implication for motivating regular HTC. In pre-ART care; CD4 counts at ART initiation increased over the calendar time for both hospital and PHCF patients, with fewer patients experiencing a late HIV stage. In ART care, hospital and PHCF patients exhibited at least similar adherence to ART, indicating a non-inferior performance of decentralized provision in Indonesia. In program costs, the average cost of providing ART care for PHCF patients was not lower than hospital provision in four sub-Saharan African countries (Rwanda, Malawi, Zambia, and Ethiopia), except in Ethiopia. Cost differences were largely attributable to differential prescribing of ART regimens between facility types and minimized with a switch to the recommended regimens. In terms of cost-effectiveness, decentralizing stable ART patients from hospitals to PHCFs for routine care (down-referral) was found to be cost-effective in Ethiopia. Economically, the extra program cost represents an affordable investment to advance the performance of the existing decentralization programming and population health. HIV care decentralization redistributes the care burden across the health system without compromising patient outcomes and favorable cost-effectiveness implications. Program expansion beyond decentralization and facility-based provision may be necessary to attain optimal coverage of HIV care in many LMICs. Identifying the optimal model of decentralization for given set of program characteristics is a key research area in the direction of optimizing program outcomes and efficiency.
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ItemMental health of primary care attendees in Kota Kinabalu, Sabah( 2018)This PhD thesis aims to investigate the mental health problems, care and service among the government clinics in Sabah, Malaysia, focusing on one of the most densely populated districts of Kota Kinabalu. Background behind undertaking of this project was based on existing epidemiological facts and studies from Sabah and peninsular Malaysia is presented. The lack of adequate mental health services, mental health research, poverty, immigration and other specific issues that are discussed in the literature review. This is a cross-sectional, general health clinic-based study among primary care attendees in the Kota Kinabalu district of Sabah. Aim: The study was designed to determine the prevalence of common mental disorders among primary care attendees in Kota Kinabalu and to identify the associated factors. It also determined the treatment gap, disability and perceived need for psychiatric treatment and care and mental health service utilization among primary care attendees with probable common mental disorder. Method: Simple random sampling method was used to select patients at three government general outpatient clinics. A total of four hundred and eighty-one patients were invited to participate. Four hundred and thirty agreed and fifty-one patients (10.6%) refused. Respondents were further interviewed by trained interviewers using a standard proforma to obtain socio-demographic data and clinical profile, Patient Health Questionnaire (PHQ), Work and Social Adjustment Scale (WSAS), General Practitioner User Perceived Need Questionnaire and Mental Health Service Utilization Questionnaire. Results: The prevalence of common mental disorders among primary care attendees were 52.1%, with 224 out of 430 respondents having a probable common mental disorder. This was higher than the previous two studies done in West Malaysia, where the prevalence of mental disorder in the primary care setting was found to be 24.7% and 26.7% respectively. Ninety-five respondents (22.1%) had more than one psychiatric diagnosis. Using univariate analysis: young age, female, monthly income less than RM1000 (1AUD=RM2.97), unemployment, student, secondary/tertiary education and recent stressors were all significantly associated with common mental disorder (PHQ positive). Using a logistic regression method, five factors were significantly predictive of common mental disorders. These were young age (18-29 years of age), female gender, higher education, income less than RM1000 and history of being physically or sexually victimized. Two hundred and nineteen (97.8%) out of two hundred and twenty-four respondents with common mental disorder had some form of disability. One hundred and sixty-three (72.8%) were slightly disabled, thirty-seven respondents (16.5%) were moderately disabled and nineteen (8.5%) were severely disabled. There was a significant and consistent positive association between the moderate disability and co-morbid common mental disorder in nearly all items of disability. The severely disabled group was shown to have a positive association with co-morbidity in two of five items of disability. These were private leisure activities and family relationship. Two hundred and five, out of two hundred and twenty-four respondents with a common mental disorder were not receiving any treatment. This was a treatment gap of 91.5%. Twenty-four respondents sought help from a traditional healer, twelve went to other professional mental health services and only three were seen by psychiatrist. Only four patients had been admitted to a psychiatric ward. The most sought out mental health services in this population were counselling (49.1%) and mental health information (41.1%). The least common mental health service provided was for medication (20.5%). The most common reason given for not accessing mental health services or treatment was “I preferred to manage myself the problem”.
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ItemCalling for the doctor: an evaluation of an after hours GP helpline in Australia( 2016)In Australia and other developed countries, the provision of after hours primary care is a challenging policy area. Limited access to after hours services, geographic inequities in provision of services, burden on hospital emergency departments, and workload for general practitioners (GPs) have prompted governments to implement after hours primary care reforms. Telephone triage and advice services have been introduced in many countries to help to improve patient access and better manage demand for both in hours and after hours health services. In Australia such developments have provoked controversy. In 2011 an after hours GP telephone advice and referral service was introduced as a supplement to existing nurse-provided telephone triage and advice services in Australian states and territories. This thesis examines the recent evolution of after hours primary care policy in Australia with a particular focus on the quality, effectiveness, and provider and consumer experience of the after hours GP helpline (the helpline) in the context of Australian primary care. Four layers of the health system - policy, service, GP provider and consumer perspectives are explored using a mixed methods realist evaluation framework. The thesis aims to identify the critical characteristics and contextual factors required to embed a GP telephone advice service in an integrated after hours healthcare system. Ten studies were conducted investigating stakeholder views, consumer utilisation, safety and quality in adult and paediatric population groups, impact on emergency department utilisation, cost considerations and GP provider and consumer experience of the helpline. Together these studies provide an in-depth portrayal of the way in which the service was conceptualised, implemented, used and experienced. The research found that the helpline was not wholly successful in integrating with or adding value to the after hours primary care system in Australia during its first two years of operation (2011-2013). Multiple theories of action were developed, identifying current and possible pathways for helpline interaction at multiple levels in the health system. These theories of the way the world works identified contextual factors and causal mechanisms that can be modified to improve the helpline’s contribution to the Australian health system. At the policy level, supportive settings that reframe the policy narrative around the helpline as a service that assists the GP workforce, as well as consumers, will increase stakeholder acceptance and consolidate political support for its continuation. Service characteristics that promote continuity of care and greater uptake by community-based GPs and high need consumers will increase reach with consumers and the acceptability of the service to GPs. Continuation of quality improvement processes that support safe and appropriate advice will increase confidence in the helpline and improve demand management in the after hours period. Recognition of a new telephone GP provider role will lead to employment opportunities and professional recognition of GPs, young and old, seeking work-life balance in a telephone clinician role. Effective communication in telephone GP advice that reduces consumer dependency and empowers consumers to make appropriate health care choices may contribute to improved health literacy in the population. With these modifications to the context and characteristics of the service, the AGPH could both contribute to, and be part of, better integrated after hours care in Australia.
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ItemMechanisms of effect: a health systems analysis of the impact of introducing treatment services for human immunodeficiency virus (HIV) into four public primary health centres in Zambia( 2013)Between 1996 and 2008 global funding for the treatment of human immuno-deficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) increased from US$300 million to an estimated US$15.6 billion. Much of this money was directed to a small number of countries such as Zambia in sub-Saharan Africa, where HIV/AIDS constitutes a major health, social and economic threat. Although the necessity and urgency of responding to the HIV epidemics in these countries was not in question, the exceptional levels of HIV funding and the rapidity of the scale-up of HIV- services did reignite a debate regarding the impact of disease-specific programs on recipient countries’ health systems. Notwithstanding the high profile nature of this debate, little empirical research exists to inform policy makers or programmers in their efforts to meet the dual aims of improving disease-specific health outcomes and simultaneously strengthening health systems. Meeting a gap in the literature, this study examines the impact of introducing donor-funded HIV services into the Zambian health system, focusing specifically on the impact on primary health ‘micro-systems’. The conceptual framework for this study draws from theory developed in the application of complexity science and systems thinking to health systems analysis, which suggests that health systems are characterised by the interconnectedness of their component parts. The multi-disciplinary framework theorises that interactions between system ‘hardware’ and system ‘software’ influence mechanisms of accountability and trust, and through these, the quality and responsiveness of service delivery within health micro-systems. This approach challenges the implicit assumptions of more reductionist frameworks, which suggest that health systems – and particularly micro-level systems – are a simple composite of individual ‘building blocks’. This study adopted a multi-case study design, with four Zambian health centres purposefully selected based on the presence of an established HIV department (more than 3 years old), and urban, peri-urban and rural characteristics. Case data collected in each facility included facility audits, direct observation of facility operations and interviews with patients, staff, and District and non-government officials. Data were triangulated and analysed for each case first, and cross-case analysis subsequently carried out to improve the analytical generalisability of the findings. The findings from this study demonstrate that the rapid scale-up of HIV services in Zambia, which focused predominantly on investing in health system hardware, acted unevenly on mechanisms of accountability and trust and had mixed outcomes on the four health centres’ overall functionality. It was revealed, for example, that the short-term gains in health worker performance achieved through investment in system hardware for HIV services were difficult to sustain, as the lack of investment in underlying mechanisms of accountability such as improved answerability and enforceability or stronger patient-provider trust, enabled perverse work norms to flourish in ways that undermined quality and responsiveness of care. The study points to the critical importance of accounting for the ideas, values and norms of actors in the health system (system software) in order to plan and deliver disease-specific interventions that achieve both their programmatic aims as well as producing long-term, system-strengthening effects. The study constitutes an important contribution to the field of health policy and systems research providing empirical evidence of the complex, social and adaptive nature of health micro-systems and demonstrating the critical value of the hardware-software construct for analysing mechanisms of effect in this domain.
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ItemExamining Victoria’s disaster mental health capacity: towards systematic disaster mental health workforce and service planning( 2013)Natural disasters increasingly impact on the Victorian population, resulting in greater calls on mental health services and providers of psychosocial support. However, little is known about Victoria’s capacity to respond to the mental health consequences of major natural disasters. It is therefore timely to examine key indicators of Victoria’s disaster mental health service and workforce capacity and to examine the strengths and limitations of current approaches to building such capacity in view of future natural disasters. To this end, the current thesis examined key indicators of, and current approaches to building, Victoria’s disaster mental health service and workforce capacity in the context of the response to Australia’s largest bushfire disaster, the Victorian Black Saturday Bushfires. Through a series of four studies, this thesis investigated strengths and limitations of novel service delivery models and capacity building approaches, and the profile and capacity of the Victorian disaster mental health workforce. Study findings will inform a more strategic approach to disaster mental health workforce and service planning, sustainable capacity building and enhanced provision of best practice mental health support to disaster-affected Victorians in the future.
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ItemThe role of the general practitioner in postnatal care: an early intervention study( 1997)This thesis deals with the role of the general practitioner (GP) in postnatal care, especially the provision of and the most appropriate timing for the traditional postnatal check-up. Chapter 1 discusses the origins of postnatal care, the common morbidities, the lack of formal research in the area and the opportunity that the routine postnatal check-up presents to general practitioners. Chapter 2 shows, by the analysis of routinely collected Medicare data, that a mother and baby will have 7.7 visits (on average) to a GP in the six months after birth and many women will attend a GP for their routine postnatal check-up. Given the frequent contacts that GPs have with mothers and babies a Statewide postal survey of 1104 general practitioners was used to obtain their views towards postnatal care. The main findings are presented in Chapter 3. Most GPs are involved in postnatal care. Female GPs have different views from male GPs as to what should take place at the routine postnatal check-up. Overall, GPs are placing too much emphasis on routine examination and neglecting many of the common problems, both physical and emotional. Many GPs lack confidence to deal with common postnatal problems. GPs provide many visits in the early weeks prior to the traditional check-up. Some GPs believed that an earlier timing for the traditional postnatal check-up might improve maternal health. Chapter 4 reports on a randomised controlled trial designed to test whether a visit to a GP one week after discharge resulted in improved maternal health, as measured by the Edinburgh Postnatal Depression Scale (EPDS), the Short Form 36 (SF 36) subscales, self-report items about physical and emotional health and items about satisfaction with the check-up. Whilst the change in timing of the check-up resulted in less routine examination and more time to talk there were no differences in maternal health between the groups. The survey of general practitioners and the randomised controlled trial of an early postnatal check-up revealed a number of problems with the current postnatal check-up. To explore these problems further the findings of the GP survey are compared with the experiences of women in the standard care group of the trial. These findings are reported in Chapter 5 and indicate that many women experience problems after childbirth and some may consult a GP about the problems. However, only the minority of women will rate the GP as 'very helpful'. Many women are dissatisfied with their postnatal check-up and the current postnatal check-up is not focussed on the common problems. Whilst the traditional postnatal check-up provides an opportunity for the general practitioner to improve maternal health, this is not likely at present. If GPs are to have a role in improving maternal health a new approach to the postnatal check-up is needed. Chapter 6 provides a framework for a postnatal check-up in general practice, which might make that difference.