Bayesian versus frequentist statistical inference for investi gating a one-off cancer cluster reported to a health department

Background The problem of silent multiple comparisons is one of the most difficult statistical problems faced by scientists. It is a particular problem for investigating a one-off cancer cluster reported to a health department because any one of hundreds, or possibly thousands, of neighbourhoods, schools, or workplaces could have reported a cluster, which could have been for any one of several types of cancer or any one of several time periods. Methods This paper contrasts the frequentist approach with a Bayesian approach for dealing with silent multiple comparisons in the context of a one-off cluster reported to a health department. Two published cluster investigations were re-analysed using the Dunn-Sidak method to adjust frequentist p-values and confidence intervals for silent multiple comparisons. Bayesian methods were based on the Gamma distribution. Results Bayesian analysis with non-informative priors produced results similar to the frequentist analysis, and suggested that both clusters represented a statistical excess. In the frequentist framework, the statistical significance of both clusters was extremely sensitive to the number of silent multiple comparisons, which can only ever be a subjective "guesstimate". The Bayesian approach is also subjective: whether there is an apparent statistical excess depends on the specified prior. Conclusion In cluster investigations, the frequentist approach is just as subjective as the Bayesian approach, but the Bayesian approach is less ambitious in that it treats the analysis as a synthesis of data and personal judgements (possibly poor ones), rather than objective reality. Bayesian analysis is (arguably) a useful tool to support complicated decision-making, because it makes the uncertainty associated with silent multiple comparisons explicit.

Safety culture research, lead indicators, and the development of safety effectiveness indicators in the construction sector

Construction sector application of Lead Indicators generally and Positive Performance Indicators (PPIs) particularly, are largely seen by the sector as not providing generalizable indicators of safety effectiveness. Similarly, safety culture is often cited as an essential factor in improving safety performance, yet there is no known reliable way of measuring safety culture. This paper proposes that the accurate measurement of safety effectiveness and safety culture is a requirement for assessing safe behaviours, safety knowledge, effective communication and safety performance. Currently there are no standard national or international safety effectiveness indicators (SEIs) that are accepted by the construction industry. The challenge is that quantitative survey instruments developed for measuring safety culture and/ or safety climate are inherently flawed methodologically and do not produce reliable and representative data concerning attitudes to safety. Measures that combine quantitative and qualitative components are needed to provide a clear utility for safety effectiveness indicators.

The effectiveness of designated driver programs

Designated driver programs aim to reduce alcohol related crashes by encouraging and facilitating a safe means of transport for those who have been drinking and by influencing attitudes and knowledge. This review discusses the use and effectiveness of designated driver programs in preventing drink driving and ultimately reducing alcohol related road trauma. The limitations of studies examining designated driver programs and recommendations for further research are also discussed. The available evidence suggests that while designated driver campaigns can successfully increase the awareness and use of designated drivers, it is less clear whether these programs lead to a reduction in drink driving and/or alcohol related crashes. Differences in the way that designated driver programs have historically been implemented may account for the inconsistent evidence for their effectiveness in reducing drink driving. There are also a variety of methodological problems relating to the evaluation of designated driver programs which need to be addressed by future research.

Passive control of a bi-ventricular assist device : an experimental and numerical investigation

For the last two decades heart disease has been the highest single cause of death for the human population. With an alarming number of patients requiring heart transplant, and donations not able to satisfy the demand, treatment looks to mechanical alternatives. Rotary Ventricular Assist Devices, VADs, are miniature pumps which can be implanted alongside the heart to assist its pumping function. These constant flow devices are smaller, more efficient and promise a longer operational life than more traditional pulsatile VADs. The development of rotary VADs has focused on single pumps assisting the left ventricle only to supply blood for the body. In many patients however, failure of both ventricles demands that an additional pulsatile device be used to support the failing right ventricle. This condition renders them hospital bound while they wait for an unlikely heart donation. Reported attempts to use two rotary pumps to support both ventricles concurrently have warned of inherent haemodynamic instability. Poor balancing of the pumps’ flow rates quickly leads to vascular congestion increasing the risk of oedema and ventricular ‘suckdown’ occluding the inlet to the pump. This thesis introduces a novel Bi-Ventricular Assist Device (BiVAD) configuration where the pump outputs are passively balanced by vascular pressure. The BiVAD consists of two rotary pumps straddling the mechanical passive controller. Fluctuations in vascular pressure induce small deflections within both pumps adjusting their outputs allowing them to maintain arterial pressure. To optimise the passive controller’s interaction with the circulation, the controller’s dynamic response is optimised with a spring, mass, damper arrangement. This two part study presents a comprehensive assessment of the prototype’s ‘viability’ as a support device. Its ‘viability’ was considered based on its sensitivity to pathogenic haemodynamics and the ability of the passive response to maintain healthy circulation. The first part of the study is an experimental investigation where a prototype device was designed and built, and then tested in a pulsatile mock circulation loop. The BiVAD was subjected to a range of haemodynamic imbalances as well as a dynamic analysis to assess the functionality of the mechanical damper. The second part introduces the development of a numerical program to simulate human circulation supported by the passively controlled BiVAD. Both investigations showed that the prototype was able to mimic the native baroreceptor response. Simulating hypertension, poor flow balancing and subsequent ventricular failure during BiVAD support allowed the passive controller’s response to be assessed. Triggered by the resulting pressure imbalance, the controller responded by passively adjusting the VAD outputs in order to maintain healthy arterial pressures. This baroreceptor-like response demonstrated the inherent stability of the auto regulating BiVAD prototype. Simulating pulmonary hypertension in the more observable numerical model, however, revealed a serious issue with the passive response. The subsequent decrease in venous return into the left heart went unnoticed by the passive controller. Meanwhile the coupled nature of the passive response not only decreased RVAD output to reduce pulmonary arterial pressure, but it also increased LVAD output. Consequently, the LVAD increased fluid evacuation from the left ventricle, LV, and so actually accelerated the onset of LV collapse. It was concluded that despite the inherently stable baroreceptor-like response of the passive controller, its lack of sensitivity to venous return made it unviable in its present configuration. The study revealed a number of other important findings. Perhaps the most significant was that the reduced pulse experienced during constant flow support unbalanced the ratio of effective resistances of both vascular circuits. Even during steady rotary support therefore, the resulting ventricle volume imbalance increased the likelihood of suckdown. Additionally, mechanical damping of the passive controller’s response successfully filtered out pressure fluctuations from residual ventricular function. Finally, the importance of recognising inertial contributions to blood flow in the atria and ventricles in a numerical simulation were highlighted. This thesis documents the first attempt to create a fully auto regulated rotary cardiac assist device. Initial results encourage development of an inlet configuration sensitive to low flow such as collapsible inlet cannulae. Combining this with the existing baroreceptor-like response of the passive controller will render a highly stable passively controlled BiVAD configuration. The prototype controller’s passive interaction with the vasculature is a significant step towards a highly stable new generation of artificial heart.

Schools' guide : How to select providers of road safety education programs for senior school students

Road safety education is not just about safe driving. Best practice road safety education seeks to improve knowledge and change attitudes relating to being safe, and making sure others are safe on the road. Typical topics might include: • Strengthening attitudes toward safe road use behaviours and avoiding risks • Supporting behaviours to ensure others are safe • Promoting knowledge of traffic rules.

The Impact of Experiential Learning in Enhancing Palliative Care Knowledge and Skills among Nurses

Nurses working in community settings are increasingly required to care for people with chronic, life limiting conditions. Innovative educational programs are required to ensure nurses are equipped to deal with this challenging area of practice. The Program of Experience in the Palliative Approach (PEPA) started in 2003 as an initiative of the Australian Government, Department of Health and Ageing. The overall aim of PEPA is to improve the quality, availability and access to palliative care for people who are dying, and their families, by improving the skills and expertise of health practitioners, and enhancing collaboration between primary and specialist palliative care services. PEPA provides nurses with an opportunity to develop knowledge and skills in the palliative approach to care through funded clinical workforce placements or workshops.

Evaluation of polycaprolactone scaffold degradation for 6 months in vitro and in vivo

The use of polycaprolactone (PCL) as a biomaterial, especially in the fields of drug delivery and tissue engineering, has enjoyed significant growth. Understanding how such a device or scaffold eventually degrades in vivo is paramount as the defect site regenerates and remodels. Degradation studies of three-dimensional PCL and PCL-based composite scaffolds were conducted in vitro (in phosphate buffered saline) and in vivo (rabbit model). Results up to 6 months are reported. All samples recorded virtually no molecular weight changes after 6 months, with a maximum mass loss of only about 7% from the PCL-composite scaffolds degraded in vivo, and a minimum of 1% from PCL scaffolds. Overall, crystallinity increased slightly because of the effects of polymer recrystallization. This was also a contributory factor for the observed stiffness increment in some of the samples, while only the PCL-composite scaffold registered a decrease. Histological examination of the in vivo samples revealed good biocompatibility, with no adverse host tissue reactions up to 6 months. Preliminary results of medical-grade PCL scaffolds, which were implanted for 2 years in a critical-sized rabbit calvarial defect site, are also reported here and support our scaffold design goal for gradual and late molecular weight decreases combined with excellent long-term biocompatibility and bone regeneration. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 90A: 906-919, 2009

A naturally shaped silicone ventricle evaluated in a mock circulation loop : a preliminary study

Mock circulation loops are used to evaluate the performance of cardiac assist devices prior to animal and clinical testing. A compressible, translucent silicone ventricle chamber that mimics the exact size, shape and motion of a failing heart is desired to assist in flow visualization studies around inflow cannulae during VAD support. The aim of this study was therefore to design and construct a naturally shaped flexible left ventricle and evaluate its performance in a mock circulation loop. The ventricle shape was constructed by the use of CT images taken from a patient experiencing cardiomyopathic heart failure and used to create a 3D image and subsequent mould to produce a silicone ventricle. Different cardiac conditions were successfully simulated to validate the ventricle performance, including rest, left heart failure and VAD support.

A review of non-traditional occupational therapy practice placement education : a focus on role-emerging and project placements

Practice placement education has been recognised as an integral and critical component of the training of occupational therapy students. Although there is an extensive body of literature on clinical education and traditional practice placement education models, there has been limited research on alternative placements.-------- This paper reviews the literature on various practice placement education models and presents a contemporary view on how it is currently delivered. The literature is examined with a particular focus on the increasing range of practice placement education opportunities, such as project and role-emerging placements. The drivers for non-traditional practice placement education include shortages of traditional placement options, health reform and changing work practices, potential for role development and influence on practice choice. The benefits and challenges of non-traditional practice placement education are discussed, including supervision issues, student evaluation, professional and personal development and the opportunity to practise clinical skills.--------- Further research is recommended to investigate occupational therapy graduates' perceptions of role-emerging and project placements in order to identify the benefits or otherwise of these placements and to contribute to the limited body of knowledge of emerging education opportunities.

Prevalence and correlates of low back pain among occupational therapy students in Northern Queensland

Background: Although low back pain (LBP) is an important issue for the health profession, few studies have examined LBP among occupational therapy students. Purpose. To investigate the prevalence and distribution of LBP, its adverse sequelae; and to identify potential risk factors.----------- Methods: In 2005, a self-reported questionnaire was administered to occupational therapy students in Northern Queensland.----------- Findings: The 12-month period-prevalence of LBP was 64.6%. Nearly half (46.9%) had experienced pain for over 2 days, 38.8% suffered LBP that affected their daily lives, and 24.5% had sought medical treatment. The prevalence of LBP ranged from 45.5 to 77.1% (p=0.004), while the prevalence of LBP symptoms persisting longer than two days was 34.1 to 62.5% (p=0.020). Logistic regression analysis indicated that year of study and weekly computer usage were statistically-significant LBP risk factors.----------- Implications: The occupational therapy profession will need to further investigate the high prevalence of student LBP identified in this study.

Implementation of a driving diary intervention to reduce aberrant driving behaviours

Crash data involving taxis indicates that such drivers are over represented in crashes and are one to two times more likely to be involved in a fatality crash. This study reports on the pre intervention survey to provide a baseline measure of the self-reported attitudes and corresponding driving behaviours of a sample of taxi drivers. Results indicate that some taxi drivers willingly admit to engaging in unsafe driving practices. In addition, preliminary results of a post intervention survey revealed that taxi drivers’ safety perceptions, attitude and behaviours improved after completing a Driving Diary intervention.

Identifying influences of driving behaviour : could the Australian work driving setting be unique?

Work-related driving safety is an emerging concern for Australian and overseas organisations. An in depth investigation was undertaken into a group of fleet drivers’ attitudes regarding what personal and environment factors have the greatest impact upon driving behaviours. A number of new and unique factors not previously identified were found including: vehicle features, vehicle ownership, road conditions, weather, etc. The major findings of the study are discussed in regards to practical solutions to improve fleet safety.

The aptitudes of allied health professionals working in remote communities

This study aimed to identify the aptitudes required in allied health professionals working in three different service delivery models serving remote locations in Northern tropical Australia. Eighteen allied health professionals including," dietetics, diabetes educators, occupational therapy, physiotherapy, psychology, podiatry, social work and speech pathology participated in this exploratory study using a narrative approach. A range of aptitudes were identified and themed under the following headings: (1) being organized but flexible, (2) cooperation and mediation, (3) culturally aware and accepting communicators, (4) knowing the community (5) resourcefulness and resilience and (6) reflectivity. Limiting factors were also deduced. Three of the themes are discussed in this paper. The study found that allied health professionals working in remote settings identified as important personal attributes not necessarily valued in metropolitan settings. Recruitment processes and education programs need to recognize the importance of personal attributes as well as professional skills.

Health professional partnerships and their impact on Aboriginal health : an occupational therapist's and Aboriginal health worker's perspective

Objective: To describe the extent and nature of demonstrated professional partnerships between occupational therapists and Aboriginal health workers in rural and remote communities of North Queensland. The study identifies ways in which professional partnerships improve client services and enhance occupational therapy outcomes through exploring the aspects of communication, collaboration and bridging cultural boundaries.---------- Design: Data collected via in-depth, semistructured telephone interviews. ---------- Setting: Aboriginal and mainstream health and human service organisations in rural and remote North Queensland. Rural and remote areas were identified using the Accessibility and Remoteness Index of Australia codes. ---------- Participants: Seven participants working in rural and remote areas of North Queensland, comprising four occupational therapists and three Aboriginal health workers. All participants were female. ---------- Results: Participants identified five core themes when describing the extent and nature of professional partnerships between occupational therapists and Aboriginal health workers. Themes include: professional interaction; perception of professional roles; benefits to the client; professional interdependence; and significance of Aboriginal culture. According to participants, when partnerships between occupational therapists and Aboriginal health workers were formed, clients received a more culturally appropriate service, were more comfortable in the presence of the occupational therapist, obtained a greater understanding of occupational therapy assessment and intervention, and felt valued in the health care process. ---------- Conclusions: This study substantiates the necessity for the formation of professional partnerships between occupational therapists and Aboriginal health workers. The findings suggest that participation in professional partnerships has positive implications for occupational therapists working with Aboriginal clients and Aboriginal health workers in rural and remote regions of North Queensland.

Upper body musculoskeletal disorders among Australian occupational therapy students

Although upper body musculoskeletal disorders (MSDs) represent an increasingly important issue for university students, few if any studies have targeted the occupational therapy faculty. Given this dearth of information, it was considered necessary to investigate a cross-section of Australian occupational therapy students by means of an established questionnaire survey. Completed replies were obtained from 95.7%, 100% and 97.7% (n = 44, 55 and 48) of students in the first, second and fourth years of a large occupational therapy school in northern Queensland, Australia.---------- The 12-month period prevalence of MSDs was as follows: neck (67.4%), shoulder (46.3%) and upper back (39.5%). Three-quarters of all students (75.5%) reported an MSD occurring in at least one of these body regions. Over half (56.5%) reported an MSD over 2 days' duration in the past year. Almost 40% (39.5%) reported an MSD that had affected their daily life, while one-quarter (25.2%) needed some type of treatment.---------- Logistic regression indicated that students aged over 21 years were almost four times more likely to report shoulder-related MSD (OR 3.7, 95%CI: 1.4-10.2). Year of study in the occupational therapy course was another important MSD correlate, with adjusted odds ratios ranging from 3.3 at the upper back (OR 3.3, 95%CI: 1.2-9.6) to 10.9 at the neck (OR 10.9, 95%CI: 3.2-43.8). Computer usage also incurred a certain degree of risk, with students who spent over 5 hours per week on the computer having an increased risk of MSD at the neck (OR 5.0, 95%CI: 1.3-21.5) and shoulder (OR 4.7, 95%CI: 1.4-18.3).---------- Overall, this study suggests that Australian occupational therapy students have a large burden from MSDs in the upper body region, even more so than other student groups and some working populations. Since the distribution of MSD risk is not uniform among them, interventions to help reduce these conditions need to be carefully targeted. Further longitudinal investigations would also be useful in determining the mechanisms and contributory factors for MSDs among this unique student population.