Melbourne School of Population and Global Health - Theses
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ItemA Desire to Flourish: The Social and Cultural Factors Shaping the Health and Identity of Queer Indigenous Australians( 2021)This thesis is an investigation of the perceptions of gay Aboriginal men in Victoria of their experiences in the health system with the aim of understanding their situation and improving their life outcomes. The research was conducted between 2015 to 2019 and involved qualitative interviews, focus groups and other research engagements such as participant observation. Employing methodologies of medical anthropology, and research approaches from the health social sciences and history, the research has resulted in a detailed picture of the encounters of queer Indigenous Australians in their efforts to be healthy and thrive. Racism and homophobia emerged as critical obstacles they faced. A multifactorial analysis of these and other themes were developed to model an approach based on social and cultural determinants of health to broaden our understandings of the health status of queer Indigenous Australians. Overall, the factors that shape the health and identity of queer Indigenous Australians are complex and dynamic because of the impact of colonisation and heteronormative imperialistic strategies. The social, cultural, and historical factors resulting from these impacts have shaped the identities of queer Indigenous people in Australia and has contributed to a significant shift in the socio-cultural practices of gender and sexual identities within this Indigenous population. This thesis provides an analysis of these factors and how a heteronormative dominant culture continues to impact queer Indigenous people’s equity to services and their health and wellbeing. Despite the discrimination faced by the queer Indigenous people interviewed in this thesis project, the findings of this thesis suggest they are health literate and proactively seek equity in health services as a desire to flourish.
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ItemExploring alcohol and other drug use among people from migrant and ethnic minority backgrounds in Australia( 2021)Evidence suggests the prevalence of alcohol and other drug (AOD) use is lower among migrant and ethnic minority groups than the wider Australian population. Although studies indicate these groups experience AOD-related harms and are under-represented in treatment, due to stigma and other barriers, our understanding of their perceptions and experiences of these issues is poor. This PhD research sought to improve understanding of the social-ecological factors that shape AOD use, enhance understanding of stigma associated with AOD use, and inform the development of interventions among migrant and ethnic minority communities in Australia. This research was based on interviews and a focus group with 21 young people from migrant and ethnic minority backgrounds, interviews with 15 service providers, and a systematic review of qualitative studies. Findings generated from young participants and service providers suggest that multiple social-ecological factors interact to shape AOD-related perceptions and experiences among migrant and ethnic minority groups. Age, gender, religion, knowledge, stress and anxiety were identified as important individual factors. Within peer groups, AOD use was a normal part of identity and facilitated feelings of belonging. However, within families and communities, AOD use was stereotyped as failure to uphold responsibilities and bad parenting. Young participants preferred seeking information and solving AOD-related problems within their friendship groups, rather than seeking professional support. This finding was echoed by service providers, who described difficulties engaging with migrant and ethnic minority groups due to the stigma attached to AOD use. Service providers recognised the need for long-term engagement and outreach to build relationships with communities but claimed that short-term and precarious funding arrangements hindered this work. The systematic review identified that stigma associated with AOD use is driven and facilitated by stereotypes, prejudice, laws and policies, socio-cultural norms, and precarious lived experiences including insecure employment, housing instability and social exclusion. Stigma attached to AOD use intersects with gender, citizenship, race and ethnicity, leading to poorer outcomes for people with multiple stigmatised identities. Treatment and harm reduction settings are considered risk environments for identification and negative labelling. Stigma manifests through exclusion, avoidance, gossip and discrimination in treatment and employment settings. Fear of stigmatisation encourages people from migrant and ethnic minority backgrounds to hide their AOD use and avoid seeking support to protect themselves and their families. Stigma has negative impacts including emotional distress, broken relationships, low self-esteem, isolation and loneliness. The findings of this body of work suggest that AOD use among migrant and ethnic minority groups is shaped by individual factors, peer groups and the risk of stigma within families, communities and services. Youth-friendly and culturally responsive interventions are needed to address AOD use, including the negative outcomes and impacts of stigma, among migrant and ethnic minority groups. Interventions should capitalise on the existing protective practices of young people and respond to the complexities that arise from precarious lived experiences and multiple stigmatised characteristics. Partnerships between service providers, researchers and communities are required to develop and evaluate programmes that meet the needs of migrant and ethnic minority groups in Australia.
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ItemAn examination of community health worker roles and program design for urban, low- and middle-income country settings( 2021)Urbanization presents new health and development challenges and opportunities for low and middle-income countries (LMICs). Effective strategies for reaching the urban poor and addressing urban determinants of health and inequities are needed. While community health workers (CHWs) are commonly employed in rural LMIC settings to reach the underserved, there has been little examination of the role of CHWs in urban settings. The aim of this study is to understand what roles CHWs could perform in the context of an urbanizing LMIC landscape and how CHW programs might be structured to operate effectively and responsively in urban contexts. This thesis utilized data from a scoping review and a case study from Ethiopia (a fast-urbanizing LMIC with an exemplar CHW program) to provide insight into the following three research questions: 1. What roles do urban CHWs perform and what evidence is there of their effectiveness and suitability in performing those roles? 2. What adaptations to urban CHW roles and program design could enhance performance? 3. How should urban CHWs be managed to support them in effectively performing their roles? My findings from the first comprehensive review of urban CHW programs demonstrate that urban CHWs are effective in many LMIC contexts and fill gaps in services not well-served by other providers. At the same time, the findings suggest that adaptations are needed to improve their suitability and performance. Following the review, I examined two adaptations intended to enhance urban CHW performance in Ethiopia - inclusion of urban CHWs as members of primary care teams and shifting from community-based to health centre-based management. I found significant opportunities and challenges associated with expanding the clinical functions of urban CHW roles. While the establishment of the primary care teams presented significant job-related advantages for CHWs and better care for clients, the program experienced significant implementation challenges. Resource gaps related to staffing, medicines, and diagnostic equipment contributed to poor implementation readiness and low willingness among clinicians and health centre managers to support the teams. The shift to health centre-led management of CHWs helped strengthen health centre linkages and supportive supervision, which in turn contributed to short-term improvements in performance; yet health centre leadership failed to sustain commitment and support for the CHWs. In contrast, local government officials provided limited technical support but were highly vested in managing the CHWs as part of the local government workforce. However, participation in non-health-related work affected CHW performance through decreased job motivation, work evasion, and poorer community receptivity. The findings demonstrate that more technical and clinical roles for urban CHWs may be important for improving client and CHW satisfaction, but expanding such roles presents significant resourcing and management challenges. Ethiopia’s strategic modifications to urban CHW roles and management arrangements highlight the importance of matching urban CHW roles with resourcing and organizational capacity, and the need for change management strategies to accompany evolution in urban CHW roles. The challenges and tensions faced by Ethiopia raise the need for more research on how to optimize urban CHW performance in LMICs.
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ItemSafewards in Victoria: A mixed methods, real-world evaluation of process, impacts, and outcomes( 2021)In Australia and internationally the ongoing use of restrictive practices in inpatient mental health services and concerns for peoples’ human rights has attracted a great deal of attention. The occurrence of conflict events, such as aggressive incidents and the use of restrictive practices, such as seclusion, to manage these events have been the source of contention. Restrictive practices result in consumers often experiencing inpatient care as custodial, unsafe, and lacking therapeutic relationships. Contemporary mental health policy and legislation focus on both the delivery of recovery-oriented care and the need to maintain safety for consumers, staff, and visitors to inpatient mental health services. Mental health professionals working in inpatient mental health services are caught between providing recovery-oriented care and a risk management culture that tolerates the use of restrictive practice. This is further complicated by the personal drive of many staff to deliver person-centered care. Over the past two decades, there has been a focus on reducing the use of restrictive practices in inpatient mental health services. Research has been conducted to understand the impact of restrictive practices on consumers and staff, the events that precede the use of restrictive practices and interventions to reduce the use of them. ‘Safewards’ has emerged as a model of care to address these issues. It includes 10 interventions designed to reduce conflict and containment in inpatient mental health wards. Beginning in the United Kingdom, modest evidence supports the implementation of Safewards to significantly reduced conflict and containment events in acute adult inpatient units, yet studies show there are challenges to achieving high fidelity implementation. The research presented in this thesis was conducted to evaluate the trial of Safewards in Victorian inpatient mental health services. In Victoria, Australia, 18 inpatient mental health wards participated in a trial of Safewards. Over a 15-month period, staff of the wards were provided Safewards training, there was a 12-week implementation period and a further 12 months of embedding Safewards in practice. The overarching aim of the research outlined in this thesis was to determine the feasibility, acceptability, impact, and outcomes of Safewards in Victoria and to identify the barriers to, and enablers of, its implementation. This research aim is addressed in five interrelated studies with a mixed methods design that are incorporated into this thesis. The findings of the studies indicate the importance of providing appropriate training to staff, which resulted in staff feeling knowledgeable, confident, and motivated to implement Safewards in their practice. The results of the studies also reveal that consumers and staff found that Safewards was both feasible and acceptable. Both consumers and staff highlight positive outcomes in terms of improved sense of safety on the wards and better consumer-staff relationships. In addition, the results presented in this thesis demonstrate that after the implementation of Safewards, rates of seclusion were significantly reduced. Applying the Consolidated Framework for Implementation Research to triangulate the results from all sources of data enabled a detailed analysis of the implementation process. The findings highlight that a number of factors can impact upon the successful implementation of Safewards and the need to develop a culture that values the potential of Safewards and prioritises and enables its implementation.
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ItemDevelopmental Origins of Cardiometabolic Health in Twins( 2021)Background Cardiometabolic diseases are the leading cause of death and disability in Australia and may have origins in early life. Unique insights into the developmental origins of health and disease (DOHaD) can be obtained from twin studies due to matching for shared genetic and environmental factors. As such, twin studies can provide greater insight into causes of disease, including genetic and environmental contributions, and are usually generalisable to non-twin populations. Despite these benefits, few twin studies have comprehensively explored the developmental origins of cardiometabolic health. Therefore, I aimed to better understand the developmental origins of cardiometabolic health in twins, by carefully and comprehensively exploring associations of gestational and birth exposures with childhood markers of cardiometabolic health. Methods To comprehensively evaluate the current knowledge of the developmental origins of cardiometabolic health in twins, I conducted three systematic reviews (Chapters 3, 10.2 and 11.2). I used the knowledge gained from these reviews to guide original data analyses using data from the Peri/Postnatal Epigenetic Twins Study (PETS, described in Chapter 5). Twin-specific regression models (described in Chapter 6) were fitted to assess the twins-as-individuals and within-between associations of birthweight (Chapter 12.2), gestational weight gain (GWG, Chapter 10.4), and gestational nutrition (Chapter 11.3) with childhood markers of cardiometabolic health. A mixed-effects model was then fitted to determine the genetic and environmental contributions to the variance of twin anthropometric measures (Chapter 12.3). Results My systematic reviews identified several limitations of previous twin studies: 1) DOHaD exposures are often limited to birthweight; 2) typically, only blood pressure or BMI are used as cardiometabolic outcomes; 3) most studies have failed to appropriately adjust for gestational age; 4) few studies used the extra information contained in data from twins; 5) twin-specific GWG recommendations are limited to women who deliver twins at greater than or equal to 37 weeks’ gestation and/or with a birthweight of at greater than or equal to 2500 grams. To address limitation #1, I explored the associations of GWG and gestational nutrition with twin cardiometabolic health, and found that GWG was associated with birth size, for example, birthweight z-scores (Beta: 0:32, 95%CI: 0:19, 0:45), and childhood growth in the PETS. Maternal macronutrient intake was also associated with birth size, for example, protein intake with birthweight z-scores (Beta: 0:25, 95%CI: 0:09, 0:41), but not with childhood markers of cardiometabolic health. To address limitations #3 and #4, I found that birthweight-for-gestational-age z-scores were associated with twins-as-individuals, within- and between-pair childhood anthropometrics, but not with blood pressure. This contradicts results from previous studies which have not adjusted for gestational age. The within-between models showed evidence for potentially causal associations of birthweight with childhood markers of cardiometabolic health. Genetic factors contributed most strongly to the variance of childhood height, weight and BMI in the PETS. Conclusion These results have improved our knowledge of the developmental origins of cardiometabolic health in twins by demonstrating that multiple early-life exposures, and not just birthweight, are associated with a range of childhood markers of cardiometabolic health. Further, these results demonstrate the value of twin studies in DOHaD research, highlight the importance of adjusting for gestational age when studying gestational exposures and birthweight, and illustrate the need for improved, twin-specific GWG and nutrition guidelines.
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ItemSustainability in chronic disease: Evaluating the factors that contribute to sustaining evidence-based health recommendations( 2021)Background Sustaining implemented evidence-based recommendations in health care has received increasing attention over recent years; however, little is still known about the factors that contribute to sustainability. This presents a challenge for researchers, program planners and policy makers planning sustainable implementation interventions to improve health care for individuals. The factors that contribute to sustaining implemented evidence-based recommendations in the chronic disease field of stroke care forms the focus of this thesis. Stroke management has undergone major advancements in recent years. The establishment of specialist stroke teams in hospital has reduced mortality and disability. As part of supporting improved access to best practice stroke care the Victorian Government funded the implementation of several evidence-based recommendations to improve care for patients across eight selected Victorian hospitals in regional and urban areas. The sustainability of three priority recommendations was evaluated for this research including the establishment of specialist stroke units, transient ischaemic attack clinics, and swallow screening programs. Aim The aim of this research was to evaluate factors that contributed to the sustainability of the three priority evidence-based stroke recommendations 2 years after financial support from the Victorian government ceased. Evaluating the factors across the eight hospitals was intended to provide an in-depth appreciation of the way the factors manifested differently in relation to particular aspects of context. Method This research followed a mixed methods multi-site (pre-post) cohort based design to evaluate the factors of sustainability related to evidence-based care delivery for acute stroke across the selected hospitals in Victoria. A sequential qualitative, quantitative, qualitative approach following method triangulation was employed. Qualitative data collection involved narrative review and in-depth one on one interviews over separate time periods to explore factors that contributed to sustainability of the implemented recommendations. Adherence to delivery of the evidence-based recommendations and in-hospital patient outcomes were evaluated using Stroke Foundation audit data. Data from the various phases were triangulated to gain insight into the overall achievement of sustainability or not and the factors that contributed to this. Results Sustained adherence was apparent for over half of the evidence-based recommendations. Improved access to stroke unit care (OR 2.2; p < 0.05; 95% CI 1.1 – 4.2) and dysphagia screening (67%, OR 2.2; p < 0.05; 95% CI 1.5 – 3.2) was sustained two years after implementation. TIA clinics were not successfully implemented or sustained. Patient outcomes did not improve from implementation to sustainability – morbidity (OR 0.55; P = < 0.05; 95% CI 0.38 – 0.82) and malnutrition incidence (OR 5.9; P = < 0.05; 95% CI 1.8 – 19.2) worsened and mortality (OR 2.10; P = > 0.05; 95% CI 0.92 – 4.8) and aspiration (OR 1.2; P = > 0.05; 95% CI 0.60 – 2.4) did not significantly change. Fifteen factors were identified as important for overall sustainability. These factors manifested differently over time across contexts and the cultural climates of the selected hospitals. Conclusion The combination of qualitative and quantitative research undertaken as part of this doctoral research provides insight into the way the factors influenced sustainability. It also provides guidance for future program planners and researchers developing sustainable implementation initiatives in the field of chronic disease.
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ItemEconomic evaluation of intensive hand rehabilitation in patients with recent traumatic tetraplegia( 2020)Background This thesis investigated the cost-effectiveness of an innovative 8-week intensive functional electrical stimulation (FES)-assisted hand therapy program for people with recent traumatic tetraplegia that was conducted alongside a pragmatic assessor-blinded phase 3 randomised controlled trial (‘SCIPA Hands On’) at seven sites across Australia and New Zealand, and the issues that emerged during the trial regarding its two multi-attribute utility instruments, Health Utility Index Mark 3 (HUI-3) and Assessment of Quality of Life-8 (AQoL-8). Methods The economic evaluation was an intention-to-treat cost-utility analysis from a third-party payer perspective over a six-month time horizon. Costs were expressed in Australian dollars (AU$); the price year was 2015. In-depth analyses of sample- and participant-level HUI-3 and AQoL-8 responses were undertaken from a subgroup of SCIPA Hands On participants with complete utility data (80% of total sample) to identify factors that may have affected the utility results. Results Irrespective of instrument, the probability of the SCIPA Hands On intervention being cost-effective was above 75% and 78% for willingness-to-pay thresholds of AU$50,000 and AU$100,000 per quality-adjusted life-year respectively. Exploratory sub-group analyses found that for the more severe AIS A or B motor complete injuries, the intervention’s cost-effectiveness probability was unlikely to be more than 55%; for less severe AIS C or D motor incomplete injuries however, it dominated standard care hand therapy alone. In-depth analyses of HUI-3 and AQoL-8 found that while there were significant improvements in some of the expected instrument attributes/items over time as hypothesised (HUI-3 dexterity and ambulation, AQoL-8 household tasks and mobility, but not family role) and significant associations between them and change in summary utility, there were some unexpected associations between change in HUI-3 summary utility and changes in HUI-3 emotion and pain, and change in AQoL-8 summary utility and changes in AQoL-8 general feeling and pain. Instrument responses appear to have been affected by secondary health conditions, hospital discharge, post-injury recovery and psychosocial adjustment. There was also evidence of potential respondent error, possibly linked to confusing or vague items and/or linked to other factors such as cognitive difficulties or fatigue, which may have underestimated the intervention’s effect. Additionally, AQoL-8 was unable to adequately capture important mobility improvement in people with incomplete injuries, and family role responses may have been affected by inconsistent conceptualisation of health with respect to inclusion/exclusion of participants’ physical limitations. Conclusion Although traumatic spinal cord injury is comparatively rare, its impact is devastating with respect to health-related quality of life (HRQoL) and high care costs over an individual’s lifetime. With life expectancy now approaching non-injured populations, full economic evaluations of interventions designed to improve physical function and HRQoL are highly desirable to assist decisions regarding the translation of these interventions into usual practice. The unique opportunity to undertake a full economic evaluation of the SCIPA Hands On intervention and to conduct in-depth analyses of the two multi-attribute utility instruments is therefore timely in view of new interventions that are under development. The findings reported in this thesis provide an important benchmark for future economic evaluations involving spinal cord injured populations, and have the potential to influence the conduct of future trials in this group.
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ItemUnderstanding factors influencing health outcomes of drug-resistant tuberculosis (DR-TB) patients attending the Programmatic Management of Drug-Resistant Tuberculosis (PMDT) model of care in Pakistan( 2021)Background: Drug-Resistant tuberculosis (DR-TB) is a complex form of TB that develops when the causative bacteria (Mycobacterium tuberculosis) become resistant to anti-TB drugs used for the treatment of primary TB. A rise in DR-TB reflects a weak health system's response to primary TB. Pakistan is ranked fifth for primary TB and fourth for DR-TB incidence in the world. In response, the national TB program (NTP) in Pakistan launched the Programmatic Management of Drug-Resistant Tuberculosis (PMDT) model of care in 2010. This model provides free healthcare services and a financial support package to DR-TB patients through specialised PMDT clinics established across the country. Despite this dedicated model of care, health outcomes of DR-TB patients remain suboptimal, with consistently low treatment success rates (TSR) and high lost-to-follow up (LTFU) and high mortality rates compared to the intended targets. The NTP, amongst other published literature, pointed towards several 'environmental' factors such as travel and its associated costs and 'treatment-related' factors such as side-effects of the drugs as being responsible for these suboptimal health outcomes. Aim: To contribute to a better understanding of factors influencing health outcomes of DR-TB patients attending PMDT clinics in Pakistan. Methods: A Practice Theory informed ethnographic study was conducted at three PMDT clinics in the Khyber-Pakhtunkhwa province in Pakistan. The analysis drew on nine months of participant observation, semi-structured in-depth interviews with the study participants, and a quantitative survey. The study participants consisted of DR-TB patients registered at the three study sites, PMDT staff, and the DR-TB managers. In total, 61 in-depth interviews were conducted with patients on-treatment, and there were 22 interviews with patients who were LTFU, describing their healthcare experiences. Thirteen interviews were conducted with the PMDT staff, examining healthcare as they understood and practiced it. At the end of the data collection at the three study sites, four in-depth interviews were conducted with the DR-TB managers to help understand the PMDT model as envisioned and prioritised at the policy level. A total of 152 patients completed the survey. Findings: The PMDT clinic staff had a disproportionate emphasis on performing only a few activities. These were collecting patients' sputum samples, sending patients for laboratory tests, and dispensing them DR-TB medicines. The staff were mostly oblivious to other essential health systems' inputs for better health outcomes such as responding to patients' queries and doubts, building trusting relationships, and creating compassionate interactions between treating staff and patients. These healthcare practices were shaped by the PMDT indicators and monitoring focus of the DR-TB managers, where achieving outputs such as dispensing medicines to patients or dispatching sputum samples to laboratories were prioritised and valued more than building patients' competencies to understand and adhere well to their treatment. Consequently, patients were often confused and overwhelmed with the demands of their long and complex treatment course. Many were taking their medicines incorrectly or not at all, while others were discontinuing treatment believing that they were wrongly diagnosed or because they were being mistreated by the PMDT staff. A further examination of the PMDT model, using the World Health Organisation's (WHO) endorsed three health system goals framework, revealed the influence of the conventional healthcare practices and the broader sociocultural environment in Pakistan in reducing this otherwise comprehensive healthcare model to only a small set of activities with potentially negative consequences for patients' health outcomes. Conclusions: There is currently limited recognition in the PMDT model of the significance of the user experience and respectful care in improving health outcomes. These limitations in the PMDT model have their origins in Pakistan's broader health system and culture where treating 'disease' is considered a priority and where patients' rights as human beings are less valued. Consequently, despite receiving quality medicines, and having access to free healthcare, patients had many grievances and mistrust in the health system, which in turn led to their suboptimal health outcomes. By developing appropriate indicators that examine the health system's responsiveness to patients' expectations and by better tailoring the monitoring and evaluation processes with these indicators, the performance of this model of care can be improved.
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ItemRegulation by Competition and health-seeking behaviour for a range of women’s and children’s health services among informal providers in Bangladesh( 2021)Although Bangladesh has achieved significant progress in health in the past decades, excess morbidity and mortality persist. Informal providers are widespread; they remain the primary source of health care for many Bangladeshi, despite an inadequate knowledge base to provide care that meets the minimum quality standard of a modern health service. Profit-making orientation often prompts them to deliver unnecessary or even harmful care. On the other hand, the public health sector is perceived to be of low quality, hindering people from using this formal sector. A suitable policy response to address the challenges posed by informal providers is hypothesised to involve the provision of effectively subsidised public health services that users can recognise as being of adequate quality, a process called Regulation by Competition. Indeed, evidence demonstrates that a key determinant of acceptable and sustained use of health services is the users’ own views on the quality of services. This PhD research aims to test the Regulation by Competition hypothesis in Bangladesh for a range of women’s and children’s health services, by assessing whether user-perceived quality of care in the publicly subsidised sector in a given market reduces the use of informal providers in that market. The analyses were undertaken in three parts. The first part was the assessment of the quality of health services for a range of women’s and children’s health services in the public sector in Bangladesh from the users’ perspective. As the initial step, we reviewed previous Discrete Choice Experiment studies (DCEs). We identified relevant studies from Bangladesh and India which present the health service attributes that are important to women when they decide to seek care. These attributes formed the basis to create quality domains and to select the quality indicators from the 2014 Bangladesh Health Facility Survey (2014 BHFS). The quality was measured by creating a user-weighted quality index, whereby the domains of the index were given weights derived from the coefficients of the conditional logit model in the Bangladesh and Indian DCEs. The indices from all included facilities were then summarised at the district level. The second part focused on assessing the pattern of informal provider utilisation for women’s and children’s health services in Bangladesh at the district level. This was done using the data from the 2014 Bangladesh Demographic and Health Survey (2014 BDHS). The final and the main part of the analyses tested the hypothesis by assessing the correlation between informal provider utilisation against user-weighted quality summaries. The study found some significant supporting evidence for the Regulation by Competition hypothesis for acute childhood illness care. The expected association between quality and informal provider use appeared and maintained when informal provider utilisation for acute childhood illness care was assessed against the highest-quality index scores at the district level in unadjusted and adjusted-for-community level characteristics models. The highest-quality score represents the best service quality that users can get from the respective district. The major policy implication of this research is that investing in the public sector is a viable strategy, not only for ensuring that everyone in the population has equal access to better quality care at a more affordable cost, but also to manage the worst quality components of the health system which largely sit in the informal private sector. Ensuring positive user experiences is likewise fundamental, through preserving respectful care aligned with cultural norms and values. It will maintain users’ high expectation of care, leading to a more active health-seeking behaviour. The current research also opens the avenue for future studies, especially around choice in health-seeking behaviour, including understanding whether and how users make choices, the patient flow and the role of information in facilitating a more active decision making. Finally, Bangladesh has given a great deal of commitment and efforts to improve the quality of care in the country through the creation of the Quality Improvement Secretariat (QIS) and many important quality standards and guidelines. It is time for Bangladesh to use the momentum it has created to harness the enthusiasm into action.
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ItemCT scan exposure and subsequent risk of cancer in the Australian Paediatric Exposure to Radiation Cohort (Aust-PERC)( 2021)While the carcinogenic effects of high-dose radiation are well-understood, there is still considerable debate about the effects at low doses. Computed tomography (CT) scans are a valuable diagnostic tool that have risen sharply in use since their introduction in the 1970s. CT scans involve low-dose radiation exposure of significantly higher dose than traditional radiography. This has raised concerns about potential radiation-attributable cancers, particularly among paediatric patients who are more susceptible to adverse radiation effects. There have been several large-scale retrospective cohort studies that have estimated the association between childhood CT scan exposure and cancer risk. However, there are remaining concerns of reverse causation and confounding. The aim of this thesis was to estimate excess cancer risks associated with CT scan exposure before age 20, using the Australian Paediatric Exposure to Radiation Cohort study (Aust-PERC). Aust-PERC is a large, retrospective, Australian cohort study that comprises more than 11 million individuals who were born after 1965 and enrolled in Medicare (Australia’s universal health insurance scheme) before the end of 2005. These individuals were probabilistically linked to national cancer and death registries to the end of 2012, giving 103,505 incident cancers and 105,124 deaths occurring between the years of 1985 and 2012. The final cohort contains all Medicare-funded services for patients under 20 years of age, including CT scans for 688,363 patients. Recently, organ doses were retrospectively estimated for CT scans. I performed a systematic review of epidemiologic studies that estimated the association between low-dose diagnostic radiation during childhood or adolescence and cancer risk. The review identified 45 articles published between 1 January 1990 and 12 February 2020. The review concluded that study quality and data findings varied by year of publication, diagnostic exposure type, and study design. I used inverse probability of treatment weighting to control for indication bias. Indications for scans were not available in Aust-PERC, so Medicare funded health care services were used as proxies for scan indicators. After weighting the cohort, CT scan exposure was associated with an increased cancer risk, with a hazard ratio (HR) of 1.06 (95% CI: 1.02, 1.10). Significantly elevated risks of brain cancer after head CT (HR= 1.52; 95% CI: 1.30, 1.76) and other solid cancer after body CT (HR= 1.09; 95% CI: 1.01, 1.18) were observed. However, no association was observed for leukaemia/myelodysplasia (HR= 1.04; 95% CI: 0.90, 1.20). Finally, I used flexible parametric models to estimate the association between increasing active marrow dose from CT exposure and excess leukaemia risk. Here, increasing cumulative active marrow dose was associated with an increase in risk of a leukaemia or myelodysplasia diagnosis (HR/100 mGy active marrow= 4.17; 95% CI: 2.31, 7.55). Positive associations were also observed for acute myeloid leukaemia and chronic myeloid leukaemia. However, increasing cumulative active marrow dose was not associated with increased risk of acute lymphoblastic leukaemia or chronic lymphoid leukaemia. The increased risk of cancer following childhood or adolescent CT scan exposure highlights the continued need for limit exposures wherever possible, and to optimise CT doses for young, radiosensitive patients.