Diagnostics For Mixture Regression Models: Applications To Public Health
Funder
National Health and Medical Research Council
Funding Amount
$128,250.00
Summary
In many public health studies, finite mixture regression models are often used to analyse data arising from heterogeneous populations. It is important to assess the stability of parameter estimates and the validity of statistical inferences when the underlying assumptions appear to be violated, but appropriate diagnostics are lacking in the literature. This research aims to develop effective diagnostic methods for assessing the adequacy of mixture regression models and the sensitivity of accompa ....In many public health studies, finite mixture regression models are often used to analyse data arising from heterogeneous populations. It is important to assess the stability of parameter estimates and the validity of statistical inferences when the underlying assumptions appear to be violated, but appropriate diagnostics are lacking in the literature. This research aims to develop effective diagnostic methods for assessing the adequacy of mixture regression models and the sensitivity of accompanying test statistics. The methodology developed will enable health care professionals to focus on substantive issues and to draw accurate and valid conclusions inferred from correlated and over-dispersed outcomes. In the presence of anomalous observations, the influence diagnostics can provide insights into the source of heterogeneity and the apparent over-dispersion, while accommodating the inherent correlation due to the longitudinal study design or nested data structure. Significance of the research lies in its scientific novelty and the breadth of its practical applications. The benefits to public health will accrue both nationally and internationally. For the empirical studies that motivated and are linked to this research, evaluation of health outcomes has significant implications in the prevention and control of recurrent urinary tract infections, hospital strategic planning, and post-stroke care and rehabilitation management. Moreover, appropriate assessment of a physical activity intervention for older adults is pertinent to falls prevention and reduction of musculoskeletal disorders among sedentary seniors.Read moreRead less
Hierarchical Finite Mixture Modelling Of Health Outcomes: A Risk-adjusted Random Effects Approach
Funder
National Health and Medical Research Council
Funding Amount
$117,000.00
Summary
In medical and health studies, finite mixture regression models have been used to analyze data arising from heterogeneous populations. Traditionally, the application of mixture models is mainly concerned with finite normal mixtures. Recent computational advances and methodological developments have enhanced the extension of the method to non-normal finite mixtures, such as the modelling of discrete responses in finite mixture of generalized linear models and overlapping phases of failure time da ....In medical and health studies, finite mixture regression models have been used to analyze data arising from heterogeneous populations. Traditionally, the application of mixture models is mainly concerned with finite normal mixtures. Recent computational advances and methodological developments have enhanced the extension of the method to non-normal finite mixtures, such as the modelling of discrete responses in finite mixture of generalized linear models and overlapping phases of failure time data in the context of survival analysis. However, due to the hierarchical study design or the data collection procedure, the inherent correlation structure and-or clustering effects present may contribute to extra variations and violation of the independence assumption, resulting in spurious associations and misleading inferences based on the finite mixture model. This project aims to present a unified approach to accommodate both heterogeneity and dependency of observations, by incorporating random effects into finite mixture regression models. The new methodology will provide an integrated framework to analyze heterogeneous and correlated health outcomes. Three empirical studies are considered, namely, evaluation of an occupational injury reduction intervention, length of hospital stay modeling, and analysis of survival times of patients after cardiac surgery. The long term benefits to bioscience are accurate and valid conclusions inferred from medical and health studies, as well as the correct identification of high-risk subgroups. For the three application areas of this project, the improved analyses will specifically enable the evaluation of a participatory ergonomics intervention, the assessment of hospital efficiency and factors influencing length of hospitalization, and the determination of effectiveness of treatments prescribed pre- and post- operation, respectively.Read moreRead less
PSA Testing: A Population-based Longitudinal Study Of Decision Making, Psychological Effects And Patterns Of Care
Funder
National Health and Medical Research Council
Funding Amount
$576,977.00
Summary
Prostate cancer is the most commonly diagnosed cancer in Australian men and the second most common cancer- related cause of death. Since being introduced into Australia in 1988 the Prostate Specific Antigen (PSA) blood test has been widely adopted as a method for detecting early-stage asymptomatic prostate cancer. However there is controversy about the potential benefits and harms of testing for prostate cancer. Little has been documented in Australia about the information men receive when consi ....Prostate cancer is the most commonly diagnosed cancer in Australian men and the second most common cancer- related cause of death. Since being introduced into Australia in 1988 the Prostate Specific Antigen (PSA) blood test has been widely adopted as a method for detecting early-stage asymptomatic prostate cancer. However there is controversy about the potential benefits and harms of testing for prostate cancer. Little has been documented in Australia about the information men receive when considering a PSA test, what happens to men after having an abnormal PSA test and the consequences of PSA testing (including physical and psychological effects). The aim of this study is to interview a representative community sample of men aged 50 to 84 years and resident in NSW to describe: (1) the decision-making process regarding PSA testing; (2) the psychological consequences of men's PSA testing experiences; and (3) patterns of care for men who have had an abnormal PSA test. The main outcomes from this study will include substantial information on the experiences of men regarding patterns of PSA participation (frequency of, and reasons for, testing), the clinical management of men who have had an abnormal PSA test, the psychological effects of PSA testing (both positive and negative) and how decisions about testing are being made. This will provide important information to assist GPs, urologists and Australian men make decisions about PSA testing. It will highlight areas of need regarding the information required by men for informed decision-making and the support they require when undergoing PSA testing to ensure positive psychological outcomes.Read moreRead less
SNAC1:A Randomised Trial Of Sentinel Node Based Management Versus Axillary Clearance For Women With Small Breast Cancers
Funder
National Health and Medical Research Council
Funding Amount
$1,338,436.00
Summary
SNAC1 compares two operations for assessing cancer spread to the lymph nodes in women with early breast cancer: 1) axillary clearance and 2)sentinel node biopsy. Axillary clearance involves removal of most lymph nodes in the armpit. In sentinel node biopsy only a few lymph nodes most closely related to the breast cancer are removed. The trial will determine if sentinel node biopsy reduces lymphoedema and gives equivalent cure rates. If it does, then it should become standard practice.
SNAC1:A Randomised Trial Of Sentinel Node Based Management Versus Axillary Clearance For Women With Small Breast Cancers
Funder
National Health and Medical Research Council
Funding Amount
$240,187.00
Summary
Over 13,000 ANZ women are diagnosed with breast cancer each year. Most need surgery to remove the cancer and determine if it has spead to glands in the armpit (axillary lymph nodes). Knowing whether the cancer has spread to the axillary lymph nodes helps determine prognosis and plan treatment. Surgical removal is the most reliable way to assess the axillary lymph nodes. SNAC1 compares two operations for assessing cancer spread to the lymph nodes in women with early breast cancer: 1) axillary cle ....Over 13,000 ANZ women are diagnosed with breast cancer each year. Most need surgery to remove the cancer and determine if it has spead to glands in the armpit (axillary lymph nodes). Knowing whether the cancer has spread to the axillary lymph nodes helps determine prognosis and plan treatment. Surgical removal is the most reliable way to assess the axillary lymph nodes. SNAC1 compares two operations for assessing cancer spread to the lymph nodes in women with early breast cancer: 1) axillary clearance and 2) sentinel node biopsy. Axillary clearance involves removal of most lymph nodes in the armpit. In sentinel node biopsy only a few lymph nodes most closely related to the breast cancer are removed. Axillary clearance is the current standard operation. However, it is associated with risks including infection, pain, stiffness, numbness and lymphoedema (arm swelling). Lymphoedema may occur in 5-50% of women treated for breast cancer and can cause major suffering and disability. In many women their breast cancer has not spread to the lymph nodes, and axillary clearance is unnecessary. Recent studies suggest sentinel node biopsy may provide as much information as axillary clearance. Scans and dye are used to help locate the sentinel nodes. Minimising the amount of surgery to the armpit should reduce the side effects. However, the long term safety and effectiveness of removing only a few nodes is unknown. The trial will determine if sentinel node biopsy reduces lymohoedema and gives equivalent cure rates. If it does, then it should become standard practice. The study complements comparable studies being done in US, UK and Europe by providing unique information about arm symptoms and quality of life. SNAC1 recruited 1,088 women in 4 years. This application is for the work needed to report on outcomes after all women have been followed for 5 years.Read moreRead less
Economic Evaluation And Health Outcomes Of Arthritis And Its Treatments
Funder
National Health and Medical Research Council
Funding Amount
$360,660.00
Summary
Musculoskeletal diseases are the most common single cause of chronic disability in Australia and total joint replacement is rapidly becoming one of the most commonly performed operations. This burden of illness is likely to increase with our ageing population and there is an urgent need to obtain data relating to the costs and outcomes in the Australian context so that appropriate planning of health services and resources can be carried out. The WHO (World Health Organisation) has declared 2000 ....Musculoskeletal diseases are the most common single cause of chronic disability in Australia and total joint replacement is rapidly becoming one of the most commonly performed operations. This burden of illness is likely to increase with our ageing population and there is an urgent need to obtain data relating to the costs and outcomes in the Australian context so that appropriate planning of health services and resources can be carried out. The WHO (World Health Organisation) has declared 2000 to 2010 the Bone and Joint Decade, recommending that research into musculoskeletal disorders be a priority. We have been recruiting and following a unique cohort of osteoarthritis and rheumatoid arthritis patients, from both the public and private health sectors, who have been carefully documenting their health outcomes, health care costs (including primary, revision and bilateral hip and knee joint replacement surgery), out-of-pocket and indirect costs related to their arthritis. Long-term follow-up is now essential to obtain a clear picture of the impact of living with arthritis over time and the cost-effectiveness and predictors of good and bad outcomes of joint replacement surgery. The information derived from this study will be useful for patients and doctors in making their decisions about treatments, as well as for health care providers in planning of health services for arthritis sufferers. Given that the cohorts are already established, the study is in a unique position to provide ongoing important longer-term data for relatively low cost.Read moreRead less
Determinants Of Successfully Living With Aphasia After Stroke: A Prospective Cohort Mixed Methods Study
Funder
National Health and Medical Research Council
Funding Amount
$469,003.00
Summary
People with the communication disability of aphasia following stroke are critical of rehabilitation services. This project seeks to determine what it takes to live successfully with aphasia so that aphasia rehabilitation can be improved. Participants will be interviewed over the first 12 months following the stroke. The most important factors contributing to success will be identified and barriers and facilitators described. The most important factors can then be targeted in rehabilitation.
A Population-based Longitudinal Study Of Cancer Survivors' Psychosocial And Physical Well Being
Funder
National Health and Medical Research Council
Funding Amount
$454,600.00
Summary
Cancer control is a National Health Priority Area. About 345,000 new cases of cancer are diagnosed in Australia each year. It is the second highest cause of death accounting for 27% of all deaths in Australia each year. Improvements in diagnosis and treatment have resulted in a growing number of people living with a history of cancer and for longer periods. Many cancer survivors report experiencing negative effects of cancer such as fatigue, anxiety, depression, and disrupted family and social r ....Cancer control is a National Health Priority Area. About 345,000 new cases of cancer are diagnosed in Australia each year. It is the second highest cause of death accounting for 27% of all deaths in Australia each year. Improvements in diagnosis and treatment have resulted in a growing number of people living with a history of cancer and for longer periods. Many cancer survivors report experiencing negative effects of cancer such as fatigue, anxiety, depression, and disrupted family and social relationships well after treatment has finished. Despite the large burden of this disease, little is known about the later effects that cancer and its treatment has on cancer survivors, their ongoing concerns, how the issues they face change over time and the type of support they need. This will be the first population-based longitudinal survey of the physical and psychosocial effects that cancer has on adult cancer survivors to be undertaken in Australia. It will follow cancer survivors for the first five years from diagnosis to provide data on important outcomes including anxiety, depression, quality of life and unmet needs. It will also provide the first population-based data on the predictors of these outcomes, including social support, coping style and patient demographic, treatment and disease characteristics. Given the large-scale cancer survivorship initiatives underway internationally, it is timely for high quality and comprehensive Australian data to be obtained. These data will provide new information on how the physical, social and emotional impact of cancer changes with time since diagnosis and a better understanding of the support desired by cancer survivors at various stages of recovery or disease progression. This information will help guide the development of policies and services that are tailored to the needs of Australian cancer survivors.Read moreRead less
Sentinel Node Biopsy Versus Axillary Clearance In Early Breast Cancer: The SNAC Trial
Funder
National Health and Medical Research Council
Funding Amount
$1,257,525.00
Summary
Over 10,000 Australian women are diagnosed with breast cancer each year. Most need surgery to remove the cancer and determine if it has spread to glands in the armpit (axillary lymph nodes). Knowing whether the cancer has spread to the axillary lymph nodes helps determine prognosis and plan treatment. Surgical removal is the most reliable way to assess the axillary lymph nodes. This study compares two operations for assessing cancer spread to the lymph nodes in women with early breast cancer: 1) ....Over 10,000 Australian women are diagnosed with breast cancer each year. Most need surgery to remove the cancer and determine if it has spread to glands in the armpit (axillary lymph nodes). Knowing whether the cancer has spread to the axillary lymph nodes helps determine prognosis and plan treatment. Surgical removal is the most reliable way to assess the axillary lymph nodes. This study compares two operations for assessing cancer spread to the lymph nodes in women with early breast cancer: 1) axillary clearance and 2) sentinel node biopsy. Axillary clearance involves removal of most lymph nodes in the armpit. In sentinel node biopsy only a few lymph nodes most closely related to the breast cancer are removed. Axillary clearance is the current standard operation. However, it is associated with risks including infection, pain, stiffness, numbness and lymphoedema (arm swelling). Lymphoedema may occur in 5-50% of women treated for breast cancer and can cause major symptoms and disabilities. In many women the breast cancer has not spread to the lymph nodes, and axillary clearance is unnecessary. Recent studies suggest sentinel node biopsy may provide as much information as axillary clearance. Scans and dye are used to help locate the sentinel nodes. Minimising the amount of surgery to the armpit should reduce the side effects. However, the long term safety and effectiveness of removing only a few nodes is unknown. This trial will determine if sentinel node biopsy reduces lymphoedema and gives equivalent cure rates. If it does, then it should become standard practice. The study compliments comparable studies being done in US, UK and Europe by providing unique information about symptoms and quality of life from the women's perspective. One thousand Australian women will take part. The is study is being conducted by Australian breast surgeons under the auspices of the Royal Australasian College of Surgeons and the NHMRC Clinical Trials Centre.Read moreRead less