Applied Epidemiology in Cardiovascular Disease and in COVID-19 in Queensland, Australia

Between February 2017 and June 2021, I undertook the Master of Philosophy in Applied Epidemiology at the Australian National University. During this period, I was employed as a cardiologist at the Sunshine Coast University Hospital in Queensland Health. My thesis presents the results of the four required field research projects. Acute Public Health Problem: The ATHENA COVID-19 Study: Part 1 - data linkage study of outcomes in people diagnosed with COVID-19 in Queensland 1 January to 31 December 2020. Part 2: linkage of general practitioner (GP) data and consent-to-recontact. The aim of Part 1 was to describe health outcomes and investigate predictors of outcomes for all people diagnosed with COVID-19 in Queensland by linking COVID-19 notification, hospital, general practice and death registry data. The aim of Part 2 was to establish a readily available and ongoing resource for access to COVID-19 patients' health care data and to the patient themselves, enabling biospecimen-related research including the study of long-COVID. The findings from Part 1 were consistent with what is known about COVID-19. This work reinforced the value of linking multiple data sources to enhance reporting of outcomes for people diagnosed with COVID-19 and provide a platform for longer term follow up. Part 2 demonstrated that the majority of COVID-19 patients are willing have their health care data, including that from general practices, used for research. They are also agreeable to being recontacted to discuss participation in COVID-19 related research. The ATHENA COVID-19 database will form a valuable future resource for research into COVID-19. Evaluation of a Surveillance System: The evaluation of Pen Computing System Population Aggregation Tool as a potential surveillance system for monitoring cardiovascular disease risk scores and appropriateness of treatment, for the Australian population. The Population Aggregation Tool Clinical Audit Tool (PAT CAT) produced by Pen Computing Systems, is widely available to Primary Health Networks across Australia, and has the capability to monitor cardiovascular disease (CVD) risk scores and treatment undertaken by GPs. This work 1) evaluated whether PAT CAT could be used as a surveillance system for monitoring absolute CVD risk scores and appropriateness of treatment 2) provided recommendations for improvement and 3) initiated actions to enable improvements. Epidemiological Project: A cross-sectional survey describing general practitioners' absolute cardiovascular disease risk assessment practices and their relationship to knowledge, attitudes and beliefs about cardiovascular disease risk in Queensland, Australia. This study described GPs absolute cardiovascular disease risk (ACVDR) self-reported assessment practices and their relationship to knowledge, attitudes and beliefs about ACVDR. The findings were although the majority of GPs report using the ACVDR calculator when undertaking an ACVDR assessment, there is a need to increase the actual proportion of eligible patients undergoing ACVDR assessment. This may be achieved by improving GP assessment practices such as GP and patient knowledge of cardiovascular disease risk, providing sufficient time and nurse-led assessment. Data Analysis: Prevalence of coronary microvascular dysfunction (CMD) in patients being investigated for chest pain in an outpatient setting, and association with typical angina symptoms: a cross-sectional study. This project demonstrated that a third of patients referred to clinics with chest pain and normal coronary arteries have CMD. Global (whole of myocardium) CMD was not associated with typical angina but the presence of CMD in the right coronary artery territory was associated with angina in both males and females. This strength of this association was similar in men and women. In the thesis I also provide evidence of presentations conducted at national conferences and teaching exercises to colleagues

The Problem of Confirmation in the Everett Interpretation

I argue that the Oxford school Everett interpretation is internally incoherent, because we cannot claim that in an Everettian universe the kinds of reasoning we have used to arrive at our beliefs about quantum mechanics would lead us to form true beliefs. I show that in an Everettian context, the experimental evidence that we have available could not provide empirical confirmation for quantum mechanics, and moreover that we would not even be able to establish reference to the theoretical entities of quantum mechanics. I then consider a range of existing Everettian approaches to the probability problem and show that they do not succeed in overcoming this incoherence

"Chest Pain Typicality" in Suspected Acute Coronary Syndromes and the Impact of Clinical Experience

BACKGROUND: Physicians rely upon chest pain history to make management decisions in patients with suspected acute coronary syndromes, particularly where the diagnosis is not immediately apparent through ECG and troponin testing. OBJECTIVE: To establish the discriminatory value of 'typicality of chest pain' and the effect of clinician experience, for the prediction of acute myocardial infarction and presence of significant coronary artery disease. METHODS: Prospective single-center observational study undertaken in a U.K. General Hospital emergency department. We recruited consecutive adults with chest pain and a non-diagnostic ECG, for whom the treating physician determined delayed troponin testing was necessary. Using their own clinical judgment, physicians recorded whether the chest pain described was typical or atypical for acute coronary syndrome. Physicians were defined as "experienced" or "novice" according to postgraduate experience. Acute myocardial infarction was adjudicated using a high-sensitivity troponin (hs-cTn) assay, while coronary artery disease was adjudicated angiographically. RESULTS: Overall, 912 patients had typicality of chest pain assessed, of whom 114/912 (12.5%) had an acute myocardial infarction and 157/912 (17.2%) underwent angiography. In patients undergoing angiography, 90/157 (57.3%) had hs-cTn elevation, of whom 60 (66.7%) had significant coronary artery disease. 67/157 (42.7%) patients had angiography without hs-cTn elevation, of these 31 (46.2%) had significant coronary artery disease. For the diagnosis of acute myocardial infarction, chest pain typicality had an area under the curve (AUC) of 0.54 (95%CI 0.49-0.60). For the prediction of significant coronary artery disease with hs-cTn elevation AUC: 0.54 (0.40-0.67), and without hs-cTn elevation AUC: 0.45 (0.31-0.59). When assessed by experienced physicians, specificity for the diagnosis of acute myocardial infarction was higher at 65.8% (63.1%-68.7%) vs. 55.4% (53.9%-56.8%) for novices. CONCLUSIONS: Subjective interpretation of 'typicality of chest pain' is of limited discriminatory value in the assessment of suspected acute coronary syndromes, in the context of a non-diagnostic ECG. Greater clinical experience improves accuracy as a rule-in tool but does not improve overall discriminatory ability

Mechanical properties of mesoporous ceria nanoarchitectures

Architectural constructs are engineered to impart desirable mechanical properties facilitating bridges spanning a thousand meters and buildings nearly 1 km in height. However, do the same 'engineering-rules' translate to the nanoscale, where the architectural features are less than 0.0001 mm in size? Here, we calculate the mechanical properties of a porous ceramic functional material, ceria, as a function of its nanoarchitecture using molecular dynamics simulation and predict its yield strength to be almost two orders of magnitude higher than the parent bulk material. In particular, we generate models of nanoporous ceria with either a hexagonal or cubic array of one-dimensional pores and simulate their responses to mechanical load. We find that the mechanical properties are critically dependent upon the orientation between the crystal structure (symmetry, direction) and the pore structure (symmetry, direction). This journal i

The ATHENA COVID-19 Study: Cohort profile and first findings for people diagnosed with COVID-19 in Queensland, 1 January to 31 December 2020

Background : To date, there are limited Australian data on characteristics of people diagnosed with COVID-19 and on how these characteristics relate to outcomes. The ATHENA COVID-19 Study was established to describe health outcomes and investigate predictors of outcomes for all people diagnosed with COVID-19 in Queensland by linking COVID-19 notification, hospital, general practice and death registry data. This paper reports on the establishment and first findings for the ATHENA COVID-19 Study. Methods : Part 1 of the ATHENA COVID-19 Study used Notifiable Conditions System data from 1 January 2020 to 31 December 2020, linked to: Emergency Department Collection data for the same period; Queensland Health Admitted Patient Data Collections (from 1 January 2010 to 30 January 2021); and Deaths Registrations data (from 1 January 2020 to 17 January 2021). Results : To 31 December 2020, a total of 1,254 people had been diagnosed with SARS-CoV-2 infection in Queensland: half were female (49.8%); two-thirds (67.7%) were aged 20–59 years; and there was an over-representation of people living in less-disadvantaged areas. More than half of people diagnosed (57.6%) presented to an emergency department (ED); 21.2% were admitted to hospital as an inpatient (median length of stay 11 days); 1.4% were admitted to an intensive care unit (82.4% of these required ventilation); and there were six deaths. Analysis of factors associated with these outcomes was limited due to small case numbers: people living in less-disadvantaged areas had a lower risk of being admitted to hospital (test for trend, p < 0.001), while those living in more remote areas were less likely than people living in major cities to present to an ED (test for trend: p=0.007), which may reflect differential health care access rather than health outcomes per se. Increasing age (test for trend, p < 0.001) and being a current/recent smoker (age-sex-adjusted relative risk: 1.61; 95% confidence interval: 1.00, 2.61) were associated with a higher risk of being admitted to hospital. Conclusion : Despite uncertainty in our estimates due to small numbers, our findings are consistent with what is known about COVID-19. Our findings reinforce the value of linking multiple data sources to enhance reporting of outcomes for people diagnosed with COVID-19 and provide a platform for longer term follow-up.This project was funded by Health Innovation, Investment and Research Office (HIIRO), Queensland Healt

The alignment of molecular cloud magnetic fields with the spiral arms in M33

The formation of molecular clouds, which serve as stellar nurseries in galaxies, is poorly understood. A class of cloud formation models suggests that a large-scale galactic magnetic field is irrelevant at the scale of individual clouds, because the turbulence and rotation of a cloud may randomize the orientation of its magnetic field. Alternatively, galactic fields could be strong enough to impose their direction upon individual clouds, thereby regulating cloud accumulation and fragmentation, and affecting the rate and efficiency of star formation. Our location in the disk of the Galaxy makes an assessment of the situation difficult. Here we report observations of the magnetic field orientation of six giant molecular cloud complexes in the nearby, almost face-on, galaxy M33. The fields are aligned with the spiral arms, suggesting that the large-scale field in M33 anchors the clouds.Comment: to appear in Natur

Debris Disks: Seeing Dust, Thinking of Planetesimals and Planets

Debris disks are optically thin, almost gas-free dusty disks observed around a significant fraction of main-sequence stars older than about 10 Myr. Since the circumstellar dust is short-lived, the very existence of these disks is considered as evidence that dust-producing planetesimals are still present in mature systems, in which planets have formed - or failed to form - a long time ago. It is inferred that these planetesimals orbit their host stars at asteroid to Kuiper-belt distances and continually supply fresh dust through mutual collisions. This review outlines observational techniques and results on debris disks, summarizes their essential physics and theoretical models, and then places them into the general context of planetary systems, uncovering interrelations between the disks, dust parent bodies, and planets. It is shown that debris disks can serve as tracers of planetesimals and planets and shed light on the planetesimal and planet formation processes that operated in these systems in the past.Comment: Review paper, accepted for publication in "Research in Astronomy and Astrophysics