1,720,985 research outputs found
Evaluating the impact of social housing remediation and regeneration on tenants’ wellbeing: Health, social connections and safety
No full textBackground – Adequate housing is a basic human right. Despite this, much of New Zealand’s housing stock is in poor condition. Notably, there has been a substantial underinvestment in renewing New Zealand’s social housing infrastructure. In part this is because the contribution of good quality social housing to tenants’ wellbeing has been undervalued. There is a need to remediate the social housing stock in New Zealand and address inequalities in quality housing.
Against a general trend, internationally and nationally, Wellington City Council and Tāmaki Regeneration Company invested in their social housing stock. Evaluating the impact of these initiatives on tenants’ wellbeing is important, to build a robust evidence base and improve knowledge about the benefits of social housing.
Wellbeing refers to a person’s welfare, quality of life, or utility, at the individual, community and societal level. It encapsulates elements of life that people value and the degree to which people can live consistently with their desires and aspirations. Various domains influence wellbeing, as outlined in wellbeing frameworks developed by the Organisation for Economic Co-operation and Development and New Zealand Treasury. This thesis focuses on a subset of domains: housing, health, social connections and safety.
Aim – The aim of this thesis was to provide a framework for measuring the impact of social housing remediation on tenants’ wellbeing at three levels:
1. Housing level: interventions made to the indoor environment of discrete units, e.g. draft stopping intervention at Marshall Court, an already upgraded Wellington City Council housing complex with 27 units
2. Complex level: interventions include changes to the physical fabric/infrastructure of units and/or environment, e.g. rebuild of a section of Arlington, Wellington City Council’s largest social housing complex, with 269 units
3. Community level: interventions include changes to the environment/urban landscape of the neighbourhood, social services for general use and social systems, e.g. remediation of 2,500 social units in three suburbs of Tāmaki, Auckland, by Tāmaki Regeneration Company.
This thesis also aimed to test the application of the frameworks and inform the debate around the New Zealand Healthy Homes Guarantee Act 2017, which proposed a minimum temperature for rental properties. Therefore, indoor temperature was a particular focus.
Methods – This thesis developed robust evaluation frameworks, informed by literature, which can be generalised and utilised across the three levels of intervention. To evaluate the natural experiment at each level and promote causal attribution, I proposed a quasi-experimental before-and-after approach using control groups.
The housing level evaluation provided a field test of the initial framework, which proved the viability of the approach. The framework was expanded for the complex level evaluation and baseline data were collected. An even larger framework was developed for the community level intervention, which has a 15–25 year construction estimate; baseline data collection is ongoing at present. Frameworks were refined and contextualised in consultation with stakeholders. Follow-up, post-intervention data collection and analysis of the complex and community levels are anticipated to be undertaken as part of a future research programme.
As the level of intervention increases in scale, an expanding range of methods and tools are recommended to evaluate the impact. At a minimum this includes surveying tenants and monitoring the physical performance of housing including temperature, humidity and energy use. Administrative data are useful to obtain health and safety information on health care utilisation, victimisation and injuries. Site specific reports such as crime prevention through environmental design, urban design and maintenance reports are also useful sources to provide context, especially with respect to understanding social connections and safety.
Results – A literature review was conducted on evaluations of physical social housing interventions. This indicated that interventions generally led to tenants having increased satisfaction with their home, improved indoor conditions, health, social connections and safety. However, it was difficult to compare project evaluations. While they had a common goal, there was no consistent framework utilised.
For this thesis, cohesive evaluation frameworks and methodologies are presented across all three levels of intervention of interest at the housing, complex and community level. In practice a number of challenges were confronted when undertaking the evaluations, particularly at the complex and community level. This thesis also addresses how these were handled.
Key results from the housing level intervention showed meaningful indoor temperature increase was possible through minor interventions. Units were 1.36°C warmer on average after the draught stopping intervention, adjusting for outdoor temperature. Tenants’ diary entries also claimed units were warmer and more comfortable post-intervention.
Baseline results from the complex and community level showed a real need for warmer units, as pre-intervention units were on average 14.9°C and 16.7°C respectively; colder than the World Health Organization recommended minimum indoor temperature of 18°C.
Conclusion – The frameworks developed in this thesis can be applied when evaluating social housing interventions with respect to tenants’ wellbeing. The importance of housing interventions, with particular regard to indoor temperature, was demonstrated, and evidence developed was used in the development of the guidelines under the Healthy Homes Guarantee Act 2017. This will ideally be used to identify effective interventions, improve wellbeing and address inequalities going forward
Surveillance gaps and System Cracks: An investigation of possible ways to improve rheumatic fever surveillance in New Zealand
No full textBackground: Rheumatic fever (RF) and its sequela rheumatic heart disease (RHD) occur at unusually high levels in New Zealand. A disease of social deprivation, RF now almost exclusively affects Māori and Pacific peoples. In 2011, the Government announced a goal to reduce the incidence of RF by two-thirds to 1.4 per 100,000 and make RF a rare occurrence for all by June 2017. The Ministry of Health identified improving RF surveillance as a major task to support this goal and consequently commissioned this project. This project aimed to describe the existing RF surveillance systems and identify potential surveillance improvements which would support more effective control and prevention of RF. It also aimed to estimate the likely true incidence and distribution of RF. A third aim was to assess the impact of certain factors on the extent and accuracy of case diagnosis, with a focus on echocardiography as a screening tool.
Methods: A surveillance sector review framework was used to describe existing RF surveillance systems (the surveillance sector) and perform a gap analysis. Interviews with key informants were an important part of this process. Key informants were also asked about factors affecting the extent and accuracy of case diagnosis. A literature review was performed, describing RF surveillance systems and screening strategies throughout the world.
Hospitalisation and notification data were obtained. Capture-recapture statistical analyses were performed to estimate the likely true incidence and distribution of RF. Data from four registers as well as Auckland register statistics were obtained and used to refine the estimates of RF incidence. The likelihood of matching individuals from one dataset to other datasets was calculated.
Results: Intensive RF surveillance is rarely performed in developed countries outside of New Zealand and parts of Australia, mainly because RF is now very rare in these other countries. New Zealand needs a single, complete RF dataset from which accurate data can be obtained. A national register is likely to be extremely useful, both for strategy-focused surveillance (for example evaluating the impact of RF prevention programs) and control-focused surveillance (case management). As the notification database, EpiSurv, has most of the required features and is supported by the legal requirement to notify RF, it could be modified to act as a national register. It could also collect information about cases’ exposures to known risk-factors. Increasing surveillance of intermediate outcomes and upstream hazards would also be beneficial. Over the period 1997-2011, it is likely there were between 2235-2337 new cases of RF, an average of 149 to 156 per year. Due to inconstant diagnostic procedures, the extent and accuracy of case diagnosis is likely to vary considerably.
Conclusions: This thesis contains a set of recommendations to improve RF surveillance. Several of these would be relatively simple extensions of the existing systems and are likely to greatly increase the quality and usefulness of the surveillance data. Steps to address other important gaps could be approached as short-to-medium term goals. While the current RF surveillance sector is flawed, its gaps are not insurmountable
Evaluating the impact of social housing remediation and regeneration on tenants’ wellbeing: Health, social connections and safety
No full textBackground – Adequate housing is a basic human right. Despite this, much of New Zealand’s housing stock is in poor condition. Notably, there has been a substantial underinvestment in renewing New Zealand’s social housing infrastructure. In part this is because the contribution of good quality social housing to tenants’ wellbeing has been undervalued. There is a need to remediate the social housing stock in New Zealand and address inequalities in quality housing.
Against a general trend, internationally and nationally, Wellington City Council and Tāmaki Regeneration Company invested in their social housing stock. Evaluating the impact of these initiatives on tenants’ wellbeing is important, to build a robust evidence base and improve knowledge about the benefits of social housing.
Wellbeing refers to a person’s welfare, quality of life, or utility, at the individual, community and societal level. It encapsulates elements of life that people value and the degree to which people can live consistently with their desires and aspirations. Various domains influence wellbeing, as outlined in wellbeing frameworks developed by the Organisation for Economic Co-operation and Development and New Zealand Treasury. This thesis focuses on a subset of domains: housing, health, social connections and safety.
Aim – The aim of this thesis was to provide a framework for measuring the impact of social housing remediation on tenants’ wellbeing at three levels:
1. Housing level: interventions made to the indoor environment of discrete units, e.g. draft stopping intervention at Marshall Court, an already upgraded Wellington City Council housing complex with 27 units
2. Complex level: interventions include changes to the physical fabric/infrastructure of units and/or environment, e.g. rebuild of a section of Arlington, Wellington City Council’s largest social housing complex, with 269 units
3. Community level: interventions include changes to the environment/urban landscape of the neighbourhood, social services for general use and social systems, e.g. remediation of 2,500 social units in three suburbs of Tāmaki, Auckland, by Tāmaki Regeneration Company.
This thesis also aimed to test the application of the frameworks and inform the debate around the New Zealand Healthy Homes Guarantee Act 2017, which proposed a minimum temperature for rental properties. Therefore, indoor temperature was a particular focus.
Methods – This thesis developed robust evaluation frameworks, informed by literature, which can be generalised and utilised across the three levels of intervention. To evaluate the natural experiment at each level and promote causal attribution, I proposed a quasi-experimental before-and-after approach using control groups.
The housing level evaluation provided a field test of the initial framework, which proved the viability of the approach. The framework was expanded for the complex level evaluation and baseline data were collected. An even larger framework was developed for the community level intervention, which has a 15–25 year construction estimate; baseline data collection is ongoing at present. Frameworks were refined and contextualised in consultation with stakeholders. Follow-up, post-intervention data collection and analysis of the complex and community levels are anticipated to be undertaken as part of a future research programme.
As the level of intervention increases in scale, an expanding range of methods and tools are recommended to evaluate the impact. At a minimum this includes surveying tenants and monitoring the physical performance of housing including temperature, humidity and energy use. Administrative data are useful to obtain health and safety information on health care utilisation, victimisation and injuries. Site specific reports such as crime prevention through environmental design, urban design and maintenance reports are also useful sources to provide context, especially with respect to understanding social connections and safety.
Results – A literature review was conducted on evaluations of physical social housing interventions. This indicated that interventions generally led to tenants having increased satisfaction with their home, improved indoor conditions, health, social connections and safety. However, it was difficult to compare project evaluations. While they had a common goal, there was no consistent framework utilised.
For this thesis, cohesive evaluation frameworks and methodologies are presented across all three levels of intervention of interest at the housing, complex and community level. In practice a number of challenges were confronted when undertaking the evaluations, particularly at the complex and community level. This thesis also addresses how these were handled.
Key results from the housing level intervention showed meaningful indoor temperature increase was possible through minor interventions. Units were 1.36°C warmer on average after the draught stopping intervention, adjusting for outdoor temperature. Tenants’ diary entries also claimed units were warmer and more comfortable post-intervention.
Baseline results from the complex and community level showed a real need for warmer units, as pre-intervention units were on average 14.9°C and 16.7°C respectively; colder than the World Health Organization recommended minimum indoor temperature of 18°C.
Conclusion – The frameworks developed in this thesis can be applied when evaluating social housing interventions with respect to tenants’ wellbeing. The importance of housing interventions, with particular regard to indoor temperature, was demonstrated, and evidence developed was used in the development of the guidelines under the Healthy Homes Guarantee Act 2017. This will ideally be used to identify effective interventions, improve wellbeing and address inequalities going forward
Acute rheumatic fever and group A Streptococcus in New Zealand: A descriptive epidemiological study
No full textAcute rheumatic fever (ARF) is a preventable immune mediated condition triggered in response to Group A Streptococcus (GAS) pharyngitis. Rheumatic heart disease (RHD) can result from a single episode of ARF and is particularly likely to occur following recurrent episodes. RHD is a serious condition which can lead to cardiac failure, stroke and early death. ARF is highly topical in New Zealand (NZ). Despite being almost eradicated from the NZ European population, ARF continues to impose an important and inequitable burden of disease in Māori and Pacific peoples. An ambitious national ARF prevention programme (RFPP) was recently implemented, with the aim of substantially reducing ARF incidence rates. Gaps in knowledge around ARF risk factors and pathogenesis impair the ability to implement prevention and control programmes that effectively reduce the burden of disease, however. Consequently the University of Otago (NZ) has recently started work on an ARF case-control study (‘RFRF study’) which aims to identify potentially modifiable risk factors and shed light into important pathogenic pathways.
This thesis contains four major aims, addressed in four parts (A-D). These aims are:
Aim 1. To assess the population exposure to GAS pharyngitis, its importance as an initiator of ARF, and risk factors for progression to ARF in NZ (addressed in parts B and C);
Aim 2. To assess the likely true incidence of ARF and identify potential risk factors for this disease in NZ (addressed in parts A and D);
Aim 3. To identify factors influencing progression from ARF to RHD (addressed in Part D);
Aim 4. To identify opportunities for reducing the incidence, inequities and impact of ARF in NZ and identify improvements to surveillance, evaluation and research to support these processes (addressed throughout the thesis).
Part A collates existing knowledge of ARF risk factors and systematically describes the epidemiology of ARF in NZ. A wide array of risk factors have been identified in the international literature, albeit fairly inconsistently. Evidence for these risk factors is grouped according to which aspect of the causal pathway it relates to. This work helped identify hypotheses which the RFRF study went on to test in the NZ population. National epidemiological analyses emphasize the dramatic ethnic and socioeconomic inequities in occurrence rates. Highlighting which NZ populations are most affected by ARF has clear indications for RFRF study case recruitment methods.
Part B investigates the role of GAS pharyngitis as the main initiator of ARF. If this was the sole initiator of ARF, then one would expect its distribution to reflect that of ARF (albeit on a much larger scale, as ARF occurs far less frequently than GAS pharyngitis). Part B investigates this hypothesis using a review of the international literature and in-depth analyses to describe the epidemiology of GAS pharyngitis key area of NZ (Auckland). It appears that around half of all children presenting to primary healthcare with sore throat symptoms and a GAS culture-positive (GAS+ve) throat swab actually have GAS pharyngitis (as opposed to GAS carriage with coincidental viral infection). Inequities in the burden of GAS pharyngitis do not reflect the astounding ethnic inequities in the occurrence of ARF. This implies that other factors may play key roles in promoting disease progression to ARF, which Parts C and D explore. These are important lessons to be learnt from the RFPP regarding the refinement of future prevention interventions, particularly around the need to target high-risk children appropriately.
Part C uses linked data to investigate the association between GAS pharyngitis and ARF, with the emphasis on potential interventions that could stop disease progression. GAS+ve pharyngitis is firmly associated with the development of ARF. By contrast, pharyngitis with Group C or Group G Streptococcus is not. The clear association between GAS pharyngitis and ARF further highlights the need for primary prevention strategies to appropriately target high-risk children.
Part D first describes the epidemiology of ARF in NZ with a view to improving national surveillance, and secondly considers ARF through a public health policy and prevention lens, again with an emphasis on lessons from the RFPP. Despite recent surveillance improvements, under-notification of cases and misdiagnoses continue to present problems. A national case register could provide standardised surveillance information and perform critical case management functions. The RFRF study pilot is described here, which showed that poor living conditions very commonly preceded ARF in the study sample. Interventions that improve housing conditions and reduce home crowding have potential to reduce rates of ARF and avert a significant burden of other preventable child morbidity and early death. This approach was not a key strategy of the RFPP, but may be important for future interventions. Disease progression, from initial hospitalisation for ARF through to ARF recurrence, RHD and death, is also explored in Part D. Māori and Pacific ARF cases are especially at risk of these outcomes. This indicates that failures in the delivery of secondary prophylaxis is an issue affecting known ARF cases. Around 65% of recently diagnosed RHD cases had no history of prior hospitalisation for ARF. This indicates that improved approaches to case finding are needed, or that broader approaches to ARF prevention are required.
Major findings of this thesis are that firstly, GAS pharyngitis does appear to be the major initiator of ARF in NZ. Secondly, ARF primary prevention interventions must be appropriately targeted to groups likely to benefit the most, and thirdly, potentially modifiable environmental risk factors may have a key role in promoting GAS pharyngitis and disease progression to ARF. There are two major themes running throughout this doctoral thesis: 1) Lessons learnt from the RFPP, and 2) Preparing for the RFRF study. The ultimate goal of this thesis is to provide high quality evidence to support policies, programmes and practices to reduce rates and inequities in the incidence and impact of ARF in NZ. A number of recommendations for improved ARF control and prevention are made based on findings from this thesis and are supported by international literature.
Acute rheumatic fever and group A Streptococcus in New Zealand: A descriptive epidemiological study
No full textAcute rheumatic fever (ARF) is a preventable immune mediated condition triggered in response to Group A Streptococcus (GAS) pharyngitis. Rheumatic heart disease (RHD) can result from a single episode of ARF and is particularly likely to occur following recurrent episodes. RHD is a serious condition which can lead to cardiac failure, stroke and early death. ARF is highly topical in New Zealand (NZ). Despite being almost eradicated from the NZ European population, ARF continues to impose an important and inequitable burden of disease in Māori and Pacific peoples. An ambitious national ARF prevention programme (RFPP) was recently implemented, with the aim of substantially reducing ARF incidence rates. Gaps in knowledge around ARF risk factors and pathogenesis impair the ability to implement prevention and control programmes that effectively reduce the burden of disease, however. Consequently the University of Otago (NZ) has recently started work on an ARF case-control study (‘RFRF study’) which aims to identify potentially modifiable risk factors and shed light into important pathogenic pathways.
This thesis contains four major aims, addressed in four parts (A-D). These aims are:
Aim 1. To assess the population exposure to GAS pharyngitis, its importance as an initiator of ARF, and risk factors for progression to ARF in NZ (addressed in parts B and C);
Aim 2. To assess the likely true incidence of ARF and identify potential risk factors for this disease in NZ (addressed in parts A and D);
Aim 3. To identify factors influencing progression from ARF to RHD (addressed in Part D);
Aim 4. To identify opportunities for reducing the incidence, inequities and impact of ARF in NZ and identify improvements to surveillance, evaluation and research to support these processes (addressed throughout the thesis).
Part A collates existing knowledge of ARF risk factors and systematically describes the epidemiology of ARF in NZ. A wide array of risk factors have been identified in the international literature, albeit fairly inconsistently. Evidence for these risk factors is grouped according to which aspect of the causal pathway it relates to. This work helped identify hypotheses which the RFRF study went on to test in the NZ population. National epidemiological analyses emphasize the dramatic ethnic and socioeconomic inequities in occurrence rates. Highlighting which NZ populations are most affected by ARF has clear indications for RFRF study case recruitment methods.
Part B investigates the role of GAS pharyngitis as the main initiator of ARF. If this was the sole initiator of ARF, then one would expect its distribution to reflect that of ARF (albeit on a much larger scale, as ARF occurs far less frequently than GAS pharyngitis). Part B investigates this hypothesis using a review of the international literature and in-depth analyses to describe the epidemiology of GAS pharyngitis key area of NZ (Auckland). It appears that around half of all children presenting to primary healthcare with sore throat symptoms and a GAS culture-positive (GAS+ve) throat swab actually have GAS pharyngitis (as opposed to GAS carriage with coincidental viral infection). Inequities in the burden of GAS pharyngitis do not reflect the astounding ethnic inequities in the occurrence of ARF. This implies that other factors may play key roles in promoting disease progression to ARF, which Parts C and D explore. These are important lessons to be learnt from the RFPP regarding the refinement of future prevention interventions, particularly around the need to target high-risk children appropriately.
Part C uses linked data to investigate the association between GAS pharyngitis and ARF, with the emphasis on potential interventions that could stop disease progression. GAS+ve pharyngitis is firmly associated with the development of ARF. By contrast, pharyngitis with Group C or Group G Streptococcus is not. The clear association between GAS pharyngitis and ARF further highlights the need for primary prevention strategies to appropriately target high-risk children.
Part D first describes the epidemiology of ARF in NZ with a view to improving national surveillance, and secondly considers ARF through a public health policy and prevention lens, again with an emphasis on lessons from the RFPP. Despite recent surveillance improvements, under-notification of cases and misdiagnoses continue to present problems. A national case register could provide standardised surveillance information and perform critical case management functions. The RFRF study pilot is described here, which showed that poor living conditions very commonly preceded ARF in the study sample. Interventions that improve housing conditions and reduce home crowding have potential to reduce rates of ARF and avert a significant burden of other preventable child morbidity and early death. This approach was not a key strategy of the RFPP, but may be important for future interventions. Disease progression, from initial hospitalisation for ARF through to ARF recurrence, RHD and death, is also explored in Part D. Māori and Pacific ARF cases are especially at risk of these outcomes. This indicates that failures in the delivery of secondary prophylaxis is an issue affecting known ARF cases. Around 65% of recently diagnosed RHD cases had no history of prior hospitalisation for ARF. This indicates that improved approaches to case finding are needed, or that broader approaches to ARF prevention are required.
Major findings of this thesis are that firstly, GAS pharyngitis does appear to be the major initiator of ARF in NZ. Secondly, ARF primary prevention interventions must be appropriately targeted to groups likely to benefit the most, and thirdly, potentially modifiable environmental risk factors may have a key role in promoting GAS pharyngitis and disease progression to ARF. There are two major themes running throughout this doctoral thesis: 1) Lessons learnt from the RFPP, and 2) Preparing for the RFRF study. The ultimate goal of this thesis is to provide high quality evidence to support policies, programmes and practices to reduce rates and inequities in the incidence and impact of ARF in NZ. A number of recommendations for improved ARF control and prevention are made based on findings from this thesis and are supported by international literature.
“We can’t find a safe or secure environment to be ourselves”: Takatāpui/LGBTIQ+ homelessness in Aotearoa New Zealand
No full textInternationally, people who identify as Lesbian, Gay, Bisexual, Transgender, Intersex, Queer, and other minority gender and sexual orientation identities (LGBTIQ+) experience disproportionately high levels of homelessness. Despite this, no research has been undertaken on Takatāpui/LGBTIQ+ homelessness in Aotearoa New Zealand. This thesis addresses this knowledge gap by utilising qualitative and quantitative methods, however, it is not an explicitly mixed methods PhD. The qualitative and quantitative strands remain separate; however, they can be used to create a more comprehensive understanding of LGBTIQ+ homelessness than if only one type of research method was used.
For the qualitative strand, constructivist grounded theory was used to analyse eight semi-structured interviews; proposing that “Experiences of Takatāpui/LGBTIQ+ homelessness are shaped by: multiple failures of support and intervention points; the necessity of survival restricting choice and agency; and the long-term effect of concealing identities and coping with shame, stigma, and trauma. Understanding experiences of Takatāpui/LGBTIQ+ homelessness demands a focus on and across systems and institutions.” Learnings from an ultimately unsuccessful attempt at participatory video with the interview participants also contribute to the grounded theory.
The quantitative strand uses the New Zealand Integrated Data Infrastructure to analyse the government service usage of a cohort of formerly homeless women. It highlights the ways in which government support systems fail vulnerable people. Despite high rates of interactions with government services, these women still became homeless and needed Housing First support. These findings demonstrate how a similarly under-researched group of women experience poverty and homelessness, and provides an intersectional understanding of how LGBTIQ+ women can potentially experience homelessness.
Experiences of Takatāpui/LGBTIQ+ homelessness are diverse and multi-faceted. The phenomenon is produced by multiple systems of oppression and failures of government support systems. These experiences were characterised by; poverty, shame, stigma, instability, and poor mental wellbeing. There is a need for targeted support for Takatāpui/LGBTIQ+ homelessness in Aotearoa New Zealand. Furthermore, this thesis highlights the importance of focusing on addressing the structural, systemic, causes of Takatāpui/LGBTIQ+ homelessness—over problematising the individual and their actions—to understand and address the phenomenon
Estimating the health burden of influenza in New Zealand
No full textBackground
Influenza causes a large number of hospitalisations and deaths each year. This thesis is the first study to use modelling in a single country to estimate the health burden of influenza across demographic characteristics (age, sex, and ethnicity) and socioeconomic status; the proportion of influenza deaths occurring inside and outside hospital; the proportions with respiratory causes compared with cardiovascular disease and other medical illnesses; and to validate modelled estimates using observations of influenza incidence and distribution.
Aims
This thesis aims to
1. Estimate the contribution of seasonal influenza to hospitalisations in New Zealand and its sociodemographic distribution.
2. Estimate the contribution of seasonal influenza to mortality in New Zealand and its sociodemographic distribution.
3. Validate modelled estimates of influenza incidence and distribution using observed influenza hospitalisation data.
4. Investigate how and where influenza kills people by major health settings and illness categories.
Methods
The main analyses used a total of over 200 quasi-Poisson and negative binomial regression models with weekly counts of hospitalisations, deaths or isolates of influenza A, B and respiratory syncytial virus. It focused on the period 1994-2008, except for the validation Chapter, in which the study period was extended to 2015 to match the observational data. The virus’ contribution to hospitalisations and deaths coded as pneumonia and influenza (P&I), respiratory, circulatory, medical illness, and all causes were modelled.
Results
The contribution of influenza to total hospitalisations and mortality was about 9 and 23 times, respectively, larger than indicated by routine coded data. Respiratory illness was the major contributor (77%) to hospitalisations attributed to influenza whereas circulatory illness made a negligible contribution. By contrast, influenza mortality included a large (37%) contribution from circulatory illness.
The elderly (80 years of age and older) had the highest influenza-attributable hospitalisation rate (327.8 per 100,000) and mortality (214.0 per 100,000). Infants also had high rates of influenza hospitalisation (245.5 per 100,000). Influenza hospitalisation and mortality also varied markedly by ethnicity and socioeconomic status.
Direct measurement and modelling produced similar rates of influenza-associated respiratory hospitalisation across sex, ethnicity and deprivation. However, modelling found the highest rates of influenza hospitalisation in the elderly (538.2 per 100,000 in those aged 80 years plus) whereas directly measured rates were highest in children 1 to 4 years of age (262.9 per 100,000).
Overall 58.1% of influenza-associated deaths occurred in hospital. The majority of these influenza-associated deaths (66.4%) were associated with respiratory illness. By contrast, circulatory illness predominated in those dying in other places (57%). Using modelled mortality (numerator) and modelled hospitalisations (denominator) data, the case fatality risk (CFR) of influenza in hospital was 12.0%. CFR varied markedly by age, ranging from 3.8% for those 20-64 years of age to 41.3% for those aged 80 years and above.
Conclusions
These results provide strong evidence for applying modelling techniques to estimate the health burden of influenza. The marked inequalities of influenza deaths and hospitalisations by sociodemographic characteristics, illness categories and health setting support prioritised interventions (notably vaccination) for these vulnerable groups and further research to identify ways of reducing these inequalities
Estimating the health burden of influenza in New Zealand
Full text linkBackground
Influenza causes a large number of hospitalisations and deaths each year. This thesis is the first study to use modelling in a single country to estimate the health burden of influenza across demographic characteristics (age, sex, and ethnicity) and socioeconomic status; the proportion of influenza deaths occurring inside and outside hospital; the proportions with respiratory causes compared with cardiovascular disease and other medical illnesses; and to validate modelled estimates using observations of influenza incidence and distribution.
Aims
This thesis aims to
1. Estimate the contribution of seasonal influenza to hospitalisations in New Zealand and its sociodemographic distribution.
2. Estimate the contribution of seasonal influenza to mortality in New Zealand and its sociodemographic distribution.
3. Validate modelled estimates of influenza incidence and distribution using observed influenza hospitalisation data.
4. Investigate how and where influenza kills people by major health settings and illness categories.
Methods
The main analyses used a total of over 200 quasi-Poisson and negative binomial regression models with weekly counts of hospitalisations, deaths or isolates of influenza A, B and respiratory syncytial virus. It focused on the period 1994-2008, except for the validation Chapter, in which the study period was extended to 2015 to match the observational data. The virus’ contribution to hospitalisations and deaths coded as pneumonia and influenza (P&I), respiratory, circulatory, medical illness, and all causes were modelled.
Results
The contribution of influenza to total hospitalisations and mortality was about 9 and 23 times, respectively, larger than indicated by routine coded data. Respiratory illness was the major contributor (77%) to hospitalisations attributed to influenza whereas circulatory illness made a negligible contribution. By contrast, influenza mortality included a large (37%) contribution from circulatory illness.
The elderly (80 years of age and older) had the highest influenza-attributable hospitalisation rate (327.8 per 100,000) and mortality (214.0 per 100,000). Infants also had high rates of influenza hospitalisation (245.5 per 100,000). Influenza hospitalisation and mortality also varied markedly by ethnicity and socioeconomic status.
Direct measurement and modelling produced similar rates of influenza-associated respiratory hospitalisation across sex, ethnicity and deprivation. However, modelling found the highest rates of influenza hospitalisation in the elderly (538.2 per 100,000 in those aged 80 years plus) whereas directly measured rates were highest in children 1 to 4 years of age (262.9 per 100,000).
Overall 58.1% of influenza-associated deaths occurred in hospital. The majority of these influenza-associated deaths (66.4%) were associated with respiratory illness. By contrast, circulatory illness predominated in those dying in other places (57%). Using modelled mortality (numerator) and modelled hospitalisations (denominator) data, the case fatality risk (CFR) of influenza in hospital was 12.0%. CFR varied markedly by age, ranging from 3.8% for those 20-64 years of age to 41.3% for those aged 80 years and above.
Conclusions
These results provide strong evidence for applying modelling techniques to estimate the health burden of influenza. The marked inequalities of influenza deaths and hospitalisations by sociodemographic characteristics, illness categories and health setting support prioritised interventions (notably vaccination) for these vulnerable groups and further research to identify ways of reducing these inequalities
Statistical Causality in participant unblinded randomised community trials.
No full textIntroduction: The double-blinded randomised control trial (RCT) has been developed in order to provide gold standard estimation of causal effects. However, in many circumstances it is impossible to design studies that meet this standard of blinding and hence this potentially introduces a placebo effect. One example of a study where it was impossible to blind the participants was the Heating Housing and Health Study (HHHS); the intervention was the installation of modern, efficient heaters in the participants’ homes. The statistical models used explicitly assume there is no placebo effect.
Method: In order to clarify the meaning of the placebo effect, we defined the contrast between the placebo effects from assignment to the treatment group and the placebo effects of assignment to the control group as the Assignment Effect. Using this definition we developed three approaches, which allow the explicit assumption of such an assignment effect.
Using the HHHS as a worked example, we explored three different approaches;
Dummy outcome variables, where the intervention is assumed to have no effect, but we assume that these variables have similar assignment effects. The observed changes in such variables are estimates of the assignment effect.
Secondly, we attempt to directly measure the susceptibility to this assignment effect by the use of proxy variables of assignment susceptibility.
Intermediate Variables. We measure the assignment effect by looking at the effects that are unexplained by changes in the intermediate variables. (In the HHHS example the direct effect of the intervention should be largely due to a rise in temperature, hence we estimate the assignment effect by health effects unexplained by temperature)
Results: We explore, through both simulated and real data, the implications of these approaches and then give recommendations on what is needed in order to use models with an assumption of an assignment effect. Combining these approaches in a Bayesian framework, we have calculated estimates of the assignment effect and updated the intervention effects in the HHHS. While the assignment effect itself was not significant with an OR (Odds Ratio) of 0.86 (0.63 to 1.20), there was little change in the size of the intervention effect for Dry Cough at night from OR= 0.50 (0.32 to 0.79) to OR= 0.53 (0.28 to 0.98), but a large reduction in the effect of the intervention on self-reported poor health from 0.46 (0.30 to 0.71) to 0.70 (0.30 to 1.63).
Conclusion: We recommend that analyses of single-blinded RCTs include a sensitivity analysis that assumes an assignment effect. We show how, with carefully chosen assumptions, it is possible to use data already collected, and a Bayesian modelling approach, to give informative estimates of the likely size of the assignment effect and hence provide a better estimate of the true effect of the intervention in participant unblinded RCTs
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