The impact of Covid-19 vaccination in Aotearoa New Zealand: A modelling study

Aotearoa New Zealand implemented a Covid-19 elimination strategy in 2020 and 2021, which enabled a large majority of the population to be vaccinated before being exposed to the virus. This strategy delivered one of the lowest pandemic mortality rates in the world. However, quantitative estimates of the population-level health benefits of vaccination are lacking. Here, we use a validated mathematical model of Covid-19 in New Zealand to investigate counterfactual scenarios with differing levels of vaccine coverage in different age and ethnicity groups. The model builds on earlier research by adding age- and time-dependent case ascertainment, the effect of antiviral medications, improved hospitalisation rate estimates, and the impact of relaxing control measures. The model was used for scenario analysis and policy advice for the New Zealand Government in 2022 and 2023. We compare the number of Covid-19 hospitalisations, deaths, and years of life lost in each counterfactual scenario to a baseline scenario that is fitted to epidemiological data between January 2022 and June 2023. Our results estimate that vaccines saved 6650 (95% credible interval [4424, 10180]) lives, and prevented 74500 [51000, 115400] years of life lost and 45100 [34400, 55600] hospitalisations during this 18-month period. Making the same comparison before the benefit of antiviral medications is accounted for, the estimated number of lives saved by vaccines increases to 7604 [5080, 11942]. Due to inequities in the vaccine rollout, vaccination rates among Māori were lower than in people of European ethnicity. Our results show that, if vaccination rates had been equitable, an estimated 11%-26% of the 292 Māori Covid-19 deaths that were recorded in this time period could have been prevented. We conclude that Covid-19 vaccination greatly reduced health burden in New Zealand and that equity needs to be a key focus of future vaccination programmes.

Selective under-representation of Pacific peoples in population estimates for health indicator measurements in Aotearoa New Zealand misinforms policy making

BACKGROUND

The Census of Populations and Dwellings' is the five yearly population count of Aotearoa New Zealand. Best available populations (BAP) are subnational projections based on census data and demographic assumptions developed for healthcare planning and funding allocation but are also used as the denominator for health indicator monitoring. Pacific people are systematically undercounted, but the impact on health statistics is not well studied. For COVID-19 vaccination coverage, health service user (HSU) data were considered a more reliable denominator than BAP but introduced new biases. We aimed to understand how the choice of denominator population impacts estimates of population size and health system performance for Pacific people at a local level.

METHODS

We described how declining census response rates affected population data quality. We compared BAP and HSU data at district level. For the indicators 'access to primary care' and 'cervical cancer screening uptake' we replaced currently used BAP denominators with HSU and examined the impact for different ethnic groups in different geographic districts.

RESULTS

Overall Census 2018 response declined by 10%, but for Māori and Pacific people by 21% and 23%, respectively. This inequitably affected BAP accuracy. Census undercount was highest in the district with the largest Pacific populations, where HSU exceeded BAP most. Notably, 'access to primary care' for Pacific people in this district consistently exceeds 100%. Using BAP, both health indicators are currently estimated as highest for Pacific people compared to other ethnic groups, but when based on HSU, they dropped to lowest. Similar, but less pronounced trends occurred in other districts. Changes in trends over time for both indicators coincided mostly with adjustments in BAP, rather than changes in the numerators.

CONCLUSIONS

The current use of BAP denominators for health statistics does not enable reliable monitoring of key health indicators for Pacific people. HSU denominators are also unsuitable for monitoring health. Exploring the feasibility of a real-time population register is strongly recommended as a new, transparent, way of obtaining more reliable, timely population data to guide policymaking and underpin a more equitable health system under the health reforms. Meanwhile, reporting of ethnic specific outcomes need to include a clear assessment of the potential for bias due to inaccurate population estimates.

Mortality risk among Autistic children and young people: A nationwide birth cohort study

LAY ABSTRACT

Existing literature indicates that Autistic people have shorter life expectancy, but little is known about the mortality risk among Autistic children and young people (0-24 years). We used a 15-year nationwide birth cohort study to estimate the mortality risk among Autistic children and young people in Aotearoa/New Zealand. The study included 895,707 children and 11,919 (1.4%) were Autistic. We found that autism was associated with a significantly higher mortality risk compared to the non-Autistic population. In addition, we found that this risk was significantly higher among females compared to males and for those with a co-occurring intellectual disability. Increased efforts are required to better meet the health needs of this population.

Measuring Māori Health, Wellbeing, and Disability in Aotearoa Using a Web-Based Survey Methodology

High-quality evidence on the prevalence and impact of health, wellbeing, and disability among Māori, and other Indigenous peoples, is crucial for mitigating health inequities. Current surveys are predominantly centred within a biomedical paradigm, with the constructs mismatched with Indigenous worldviews. We aimed to develop and deploy an accessible and culturally grounded survey exploring Māori health, wellbeing, and disability using a Kaupapa Māori Research methodology. An extensive codesign process with Māori community partners interrogated all aspects of the design to ensure the process and outcomes met the needs of Māori. A large-scale, nationally representative survey of people of Māori descent was conducted. We used a multi-modal deployment approach that included online and alternate methods of completion. Our analysis included a novel dual-weighting system to ensure generalisability of results to the national Māori population. This achieved a survey of 7230 participants, a sample size comparable with government-administered surveys. The response rate was 11.1%, with 7.3% opting for alternate methods. A high completion rate of 93.4% was observed. This approach demonstrated a high level of engagement, resulting in an unprecedented collection of Māori health, wellbeing, and disability data. This highlights the importance of Indigenous codesign for ensuring accessible and culturally appropriate survey methods.

The August 2020 COVID-19 outbreak in Aotearoa, New Zealand: Delayed contact tracing for Pacific people contributes to widening health disparities

Background

After COVID-19 arrived in New Zealand, a national system was developed to improve the efficiency of contact tracing. The first outbreak was followed by a period of 'COVID-19 elimination', until a community outbreak occurred in August 2020. We describe the characteristics of cases and their contacts during this outbreak, focused on the results of contact tracing.

Methods

COVID-19 case data from the national surveillance database were linked to contacts from the national contact tracing database. Demographic and clinical characteristics of cases, number of contacts, and timeliness of contact tracing were analysed by ethnicity.

Findings

Most of the 179 cases were Pacific people (59%) or Māori (25%), living in areas of high socioeconomic deprivation, who had higher rates of comorbidity and accounted for almost all (21/22) hospitalisations, all 8 ICU admissions and all 3 deaths. Only 6% belonged to the European majority ethnic group. Of 2,528 registered contacts, 46% were Pacific, 14% Māori and 19% European. Only contacts that were reached were registered. Overall, 41% of contacts were reached within 4 days of onset of disease of the case, which was significantly lower for Pacific (31%) than for other ethnic groups.

Interpretation

Our findings confirm the greater health burden that ethnic minorities face from COVID-19. The significant delay in the timeliness of care for Pacific people shows that the public health response was inequitable for those at highest risk. Tailored public health responses and better registration of marginalised groups are necessary to provide better access to services and to improve insights for optimal future outbreak management.

Māori and Linked Administrative Data: A Critical Review of the Literature and Suggestions to Realise Māori Data Aspirations

Linked data presents different social and ethical issues for different contexts and communities. The Statistics New Zealand Integrated Data Infrastructure (IDI) is a collection of de-identified whole-population administrative datasets that researchers are increasingly using to answer pressing social and policy research questions. Our work seeks to provide an overview of the IDI, associated issues for Māori (the Indigenous peoples of New Zealand), and steps to realise Māori data aspirations. In this paper, we first introduce the IDI including what it is and how it developed. We then move to an overview of Māori Data Sovereignty. Our paper then turns to examples of organisations, agreements, and frameworks which seek to make the IDI and data better for Māori communities. We then discuss the main issues with the IDI for Māori including technical issues, deficit-framed work, involvement from communities, consent, social license, further data linkage, and barriers to access for Māori. We finish with a set of recommendations around how to improve the IDI for Māori, making sure that Māori can get the most out of administrative data for our communities. These include the need to build data researcher capacity and capability for Māori, Māori data co-governance and accountability, reducing practical and skill barriers for access by Māori and Māori organisations, providing robust, consistent and transparent practice exemplars for best practice, and potentially even abolishing the IDI and starting again. These issues are being worked through via Indigenous engagement and co-governance processes that could provide useful exemplars for Indigenous and community engagement with linked data resources.

Assessment of Ethnic Inequities and Subpopulation Estimates in COVID-19 Vaccination in New Zealand

This cross-sectional study investigates the outcomes of different population estimate methodologies on relative gaps in COVID-19 vaccination between ethnic groups and the resulting population risk among people in New Zealand.

Genomic discrimination in New Zealand health and life insurance. AGenDA: Against Genomic Discrimination in Aotearoa

Nil.

Patient perspectives on the use of health information

AIM

This survey aimed to investigate patient perspectives, including preferences, needs and concerns, on the use of, and access to, individual healthcare information.

METHOD

A mixed-methods cross-sectional survey of adult patients (n=1,377) in Waitematā District Health Board inpatient and outpatient services during November-December 2020. The survey was online and on paper and available in 10 languages.

RESULTS

Over 80% of participants were comfortable with their health information being used across the scenarios presented (range: 81-89%). Māori were significantly more likely than non-Māori to be comfortable with their health information being combined with the health information of others to better understand population needs (p=0.006). The level of comfort with the use of individual health information was related to assurances that its use was for public good, data were stored securely, individual privacy was maintained, the information was accurate and there was communication on how it was used.

DISCUSSION

This study has shown that most healthcare consumers are comfortable with the health service using their de-identified health information beyond their care if it benefits others.

Māori and Pacific people in New Zealand have a higher risk of hospitalisation for COVID-19

AIMS

We aim to quantify differences in clinical outcomes from COVID-19 infection in Aotearoa New Zealand by ethnicity and with a focus on risk of hospitalisation.

METHODS

We used data on age, ethnicity, deprivation index, pre-existing health conditions and clinical outcomes on 1,829 COVID-19 cases reported in New Zealand. We used a logistic regression model to calculate odds ratios for the risk of hospitalisation by ethnicity. We also considered length of hospital stay and risk of fatality.

RESULTS

After controlling for age and pre-existing conditions, we found that Māori have 2.50 times greater odds of hospitalisation (95% CI 1.39-4.51) than non-Māori non-Pacific people. Pacific people have three times greater odds (95% CI 1.75-5.33).

CONCLUSIONS

Structural inequities and systemic racism in the healthcare system mean that Māori and Pacific communities face a much greater health burden from COVID-19. Older people and those with pre-existing health conditions are also at greater risk. This should inform future policy decisions including prioritising groups for vaccination.

Use of Genomics to Track Coronavirus Disease Outbreaks, New Zealand

Real-time genomic sequencing has played a major role in tracking the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), contributing greatly to disease mitigation strategies. In August 2020, after having eliminated the virus, New Zealand experienced a second outbreak. During that outbreak, New Zealand used genomic sequencing in a primary role, leading to a second elimination of the virus. We generated genomes from 78% of the laboratory-confirmed samples of SARS-CoV-2 from the second outbreak and compared them with the available global genomic data. Genomic sequencing rapidly identified that virus causing the second outbreak in New Zealand belonged to a single cluster, thus resulting from a single introduction. However, successful identification of the origin of this outbreak was impeded by substantial biases and gaps in global sequencing data. Access to a broader and more heterogenous sample of global genomic data would strengthen efforts to locate the source of any new outbreaks.

The relationship between income poverty and child hospitalisations in New Zealand: Evidence from longitudinal household panel data and Census data

Background

Very little high quality evidence exists on the causal relationship between income poverty and childhood health. We provide a comprehensive overview of the association between household income poverty and hospitalisations for children.

Methods

We used New Zealand’s Integrated Data Infrastructure (IDI) to link income poverty data from the Survey of Family, Income and Employment (SoFIE; n = 21,759 households) and the 2013 New Zealand Census (n = 523,302 households) to publicly funded hospital records of children aged 0–17 (SoFIE: n = 39,459; Census, n = 986,901). Poverty was defined as equivalised household income below 60% of the median income, calculated both before and after housing costs, and using both self-reported and tax-recorded income.

Results

Correlations for the association between income poverty and hospitalisation were small (ranging from 0.02 to 0.05) and risk ratios were less than 1.35 for all but the rarest outcome—oral health hospitalisation. Weak or absent associations were apparent across age groups, waves of data collection, cumulative effects, and for estimates generated from fixed effects models and random effect models adjusted for age and ethnicity. Alternative measures of deprivation (area-level deprivation and material deprivation) showed stronger associations with hospitalisations (risk ratios ranged from 1.27–2.55) than income-based poverty measures.

Conclusion

Income poverty is at best weakly associated with hospitalisation in childhood. Measures of deprivation may have a stronger association. Income measures alone may not be sufficient to capture the diversity of household economic circumstances when assessing the poverty-health relationship.

Genomic Evidence of In-Flight Transmission of SARS-CoV-2 Despite Predeparture Testing

Since the first wave of coronavirus disease in March 2020, citizens and permanent residents returning to New Zealand have been required to undergo managed isolation and quarantine (MIQ) for 14 days and mandatory testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of October 20, 2020, of 62,698 arrivals, testing of persons in MIQ had identified 215 cases of SARS-CoV-2 infection. Among 86 passengers on a flight from Dubai, United Arab Emirates, that arrived in New Zealand on September 29, test results were positive for 7 persons in MIQ. These passengers originated from 5 different countries before a layover in Dubai; 5 had negative predeparture SARS-CoV-2 test results. To assess possible points of infection, we analyzed information about their journeys, disease progression, and virus genomic data. All 7 SARS-CoV-2 genomes were genetically identical, except for a single mutation in 1 sample. Despite predeparture testing, multiple instances of in-flight SARS-CoV-2 transmission are likely.

Estimated inequities in COVID-19 infection fatality rates by ethnicity for Aotearoa New Zealand

AIMS

There is limited evidence as to how clinical outcomes of COVID-19 including fatality rates may vary by ethnicity. We aim to estimate inequities in infection fatality rates (IFR) in New Zealand by ethnicity.

METHODS

We combine existing demographic and health data for ethnic groups in New Zealand with international data on COVID-19 IFR for different age groups. We adjust age-specific IFRs for differences in unmet healthcare need, and comorbidities by ethnicity. We also adjust for life expectancy reflecting evidence that COVID-19 amplifies the existing mortality risk of different groups.

RESULTS

The IFR for Māori is estimated to be 50% higher than that of non-Māori, and could be even higher depending on the relative contributions of age and underlying health conditions to mortality risk.

CONCLUSIONS

There are likely to be significant inequities in the health burden from COVID-19 in New Zealand by ethnicity. These will be exacerbated by racism within the healthcare system and other inequities not reflected in official data. Highest risk communities include those with elderly populations, and Māori and Pacific communities. These factors should be included in future disease incidence and impact modelling.

Hereditary diffuse gastric cancer: updated clinical practice guidelines

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome that is characterised by a high prevalence of diffuse gastric cancer and lobular breast cancer. It is largely caused by inactivating germline mutations in the tumour suppressor gene CDH1, although pathogenic variants in CTNNA1 occur in a minority of families with HDGC. In this Policy Review, we present updated clinical practice guidelines for HDGC from the International Gastric Cancer Linkage Consortium (IGCLC), which recognise the emerging evidence of variability in gastric cancer risk between families with HDGC, the growing capability of endoscopic and histological surveillance in HDGC, and increased experience of managing long-term sequelae of total gastrectomy in young patients. To redress the balance between the accessibility, cost, and acceptance of genetic testing and the increased identification of pathogenic variant carriers, the HDGC genetic testing criteria have been relaxed, mainly through less restrictive age limits. Prophylactic total gastrectomy remains the recommended option for gastric cancer risk management in pathogenic CDH1 variant carriers. However, there is increasing confidence from the IGCLC that endoscopic surveillance in expert centres can be safely offered to patients who wish to postpone surgery, or to those whose risk of developing gastric cancer is not well defined.

Chemical Composition of the Rectal Gland and Volatiles Released by Female Queensland Fruit Fly, Bactrocera tryoni (Diptera: Tephritidae)

The composition of the rectal gland secretion and volatiles emitted by female Queensland fruit fly, Bactrocera tryoni was investigated. Esters were found to be the main compounds in the gland extracts and headspace, while amides were the minor compounds in the gland extracts and headspace. Ethyl dodecanoate, ethyl tetradecanoate, ethyl (Z9)-hexadecenoate and ethyl palmitate were the main esters in the gland extracts, while ethyl dodecanoate and ethyl tetradecanoate were the main esters in the headspace. Four amides (N-(3-methylbutyl)acetamide), N-(2-methylbutyl)propanamide, N-(3-methylbutyl)propanamide, and N-(3-methylbutyl)-2-methylpropanamide were found in the gland extracts and the headspace. Among the amides, N-(3-methylbutyl)acetamide and N-(3-methylbutyl)propanamide were the main amides in the gland extracts and the headspace. Traces of three spiroacetals were found both in the gland extracts and in the headspace. (E,E)-2,8-Dimethyl-1,7-dioxaspiro[5.5]undecane, (E,E)-2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecane, (E,E)-2-propyl-8-methyl-1,7-dioxaspiro[5.5]undecane. All compounds found in the headspace were present in the extract of the rectal gland suggesting that the rectal gland is the main source of the headspace volatiles, whose function remains to be elucidated. This is the first comprehensive chemical analysis of the rectal gland secretions and volatiles of female B. tryoni, and further laboratory and field bioassays are required to determine the function of compounds identified in this study. Discovery of the same amides previously identified in the male rectal gland in the female rectal gland raises questions about the pheromonal role previously suggested for these compounds.

Leafroller-induced phenylacetonitrile and acetic acid attract adult Lobesia botrana in European vineyards

We recently identified unique caterpillar-induced plant volatile compounds emitted from apple leaves infested with the larvae of various leafroller species. In subsequent field tests, binary blends of phenylacetonitrile+acetic acid and 2-phenylethanol+acetic acid were found to be attractive to a range of tortricid leafroller species (Tortricidae: Tortricinae) in both the Southern and Northern Hemispheres. In this work, the caterpillar-induced plant volatiles from the apple-leafroller system were tested in two vineyards in Spain and Hungary for their attractiveness to the grape frugivore Lobesia botrana (Tortricidae: Olethreutinae). As seen for Tortricinae species, a binary blend of phenylacetonitrile+acetic acid attracted significantly more male and female L. botrana to traps than acetic acid or blank lures. Traps baited with other caterpillar-induced plant volatile compounds (benzyl alcohol, 2-phenylethanol, indole, and (E)-nerolidol, each as a binary blend with acetic acid) did not catch significantly more moths than traps containing acetic acid alone. The catches of male and female moths support an optimistic future for new products in female tortricid surveillance and control that are based on combinations of kairomone compounds released from larval-damaged foliage.

Germline CDH1 mutations are a significant contributor to the high frequency of early-onset diffuse gastric cancer cases in New Zealand Māori

New Zealand Māori have a considerably higher incidence of gastric cancer compared to non-Māori, and are one of the few populations worldwide with a higher prevalence of diffuse-type disease. Pathogenic germline CDH1 mutations are causative of hereditary diffuse gastric cancer, a cancer predisposition syndrome primarily characterised by an extreme lifetime risk of developing diffuse gastric cancer. Pathogenic CDH1 mutations are well described in Māori families in New Zealand. However, the contribution of these mutations to the high incidence of gastric cancer is unknown. We have used next-generation sequencing, Sanger sequencing, and Multiplex Ligation-dependent Probe Amplification to examine germline CDH1 in an unselected series of 94 Māori gastric cancer patients and 200 healthy matched controls. Overall, 18% of all cases, 34% of cases diagnosed with diffuse-type gastric cancer, and 67% of cases diagnosed aged less than 45 years carried pathogenic CDH1 mutations. After adjusting for the effect of screening known HDGC families, we estimate that 6% of all advanced gastric cancers and 13% of all advanced diffuse-type gastric cancers would carry germline CDH1 mutations. Our results demonstrate that germline CDH1 mutations are a significant contributor to the high frequency of diffuse gastric cancer in New Zealand Māori.

Genomic medicine must reduce, not compound, health inequities: the case for hauora-enhancing genomic resources for New Zealand

Precision medicine seeks to draw on data from both individuals and populations across disparate domains to influence and support diagnosis, management and prevention in healthcare at the level of the individual patient and their family/whānau. Central to this initiative is incorporating the effects of the inherent variation that lies within genomes and can influence health outcomes. Identifying and interpreting such variation requires an accurate, valid and representative dataset to firstly define what variants are present and then assess the potential relevance for the health of a person, their family/whānau and the wider community to which they belong. Globally the variation embedded within genomes differs enormously and has been shaped by the size, constitution, historical origins and evolutionary history of their source populations. Māori, and more broadly Pacific peoples, differ substantially in terms of genomic variation compared to the more closely studied European and Asian populations. In the absence of accurate genomic information from Māori and Pacific populations, the precise interpretation of genomic data and the success and benefits of genomic medicine will be disproportionately less for those Māori and Pacific peoples. In this viewpoint article we, as a group of healthcare professionals, researchers and scientists, present a case for assembling genomic resources that catalogue the characteristics of the genomes of New Zealanders, with an emphasis on peoples of Māori and Polynesian ancestry, as a healthcare imperative. In proposing the creation of these resources, we note that their governance and management must be led by iwi and Māori and Pacific representatives. Assembling a genomic resource must be informed by cultural concepts and values most especially understanding that, at a physical and spiritual level, whakapapa is embodied within the DNA of a person. Therefore DNA and genomic data that connects to whakapapa (genealogy) is considered a taonga (something precious and significant), and its storage, utilisation and interpretation is a culturally significant activity. Furthermore, such resources are not proposed to primarily enable comparisons between those with Māori and broader Pacific ancestries and other Aotearoa peoples but to place an understanding of the genetic contributors to their health outcomes in a valid context. Ongoing oversight and governance of such taonga by Māori and Pacific representatives will maximise hauora (health) while also minimising the risk of misuse of this information.

Risk of stomach cancer in Aotearoa/New Zealand: A Māori population based case-control study

Māori, the indigenous people of New Zealand, experience disproportionate rates of stomach cancer, compared to non-Māori. The overall aim of the study was to better understand the reasons for the considerable excess of stomach cancer in Māori and to identify priorities for prevention. Māori stomach cancer cases from the New Zealand Cancer Registry between 1 February 2009 and 31 October 2013 and Māori controls, randomly selected from the New Zealand electoral roll were matched by 5-year age bands to cases. Logistic regression was used to estimate odd ratios (OR) and 95% confidence intervals (CI) between exposures and stomach cancer risk. Post-stratification weighting of controls was used to account for differential non-response by deprivation category. The study comprised 165 cases and 480 controls. Nearly half (47.9%) of cases were of the diffuse subtype. There were differences in the distribution of risk factors between cases and controls. Of interest were the strong relationships seen with increased stomach risk and having >2 people sharing a bedroom in childhood (OR 3.30, 95%CI 1.95–5.59), testing for H pylori (OR 12.17, 95%CI 6.15–24.08), being an ex-smoker (OR 2.26, 95%CI 1.44–3.54) and exposure to environmental tobacco smoke in adulthood (OR 3.29, 95%CI 1.94–5.59). Some results were attenuated following post-stratification weighting. This is the first national study of stomach cancer in any indigenous population and the first Māori-only population-based study of stomach cancer undertaken in New Zealand. We emphasize caution in interpreting the findings given the possibility of selection bias. Population-level strategies to reduce the incidence of stomach cancer in Māori include expanding measures to screen and treat those infected with H pylori and a continued policy focus on reducing tobacco consumption and uptake.

Quality of hospital care for Māori patients in New Zealand: retrospective cross-sectional assessment

BACKGROUND

New Zealand has a substantial indigenous minority--the Māori--that has considerably worse health status than the majority population. We aimed to assess possible disparities in quality of hospital care for Māori with data on preventable adverse events as an indicator of suboptimum treatment.

METHODS

We undertook a nationally representative cross-sectional survey of admissions to general public hospitals with more than 100 beds providing acute care. A sample of 6579 patients admitted in 1998 to 13 hospitals was selected by stratified systematic list sample. We did a two-stage retrospective assessment of records by structured implicit review. Outcome measures were occurrence, effect, and preventability of adverse events.

FINDINGS

Māori accounted for just greater than 15% of admissions and were on average younger, were more likely to be from from deprived areas, had a different case mix, and were in hospital for a shorter stay compared with patients of non-Māori/non-Pacific origin. Overall, after age standardisation, 14% of admissions for Māori were associated with an adverse event, compared with 11% for non-Māori/non-Pacific patients (p=0.01 for difference between groups). For preventable, in-hospital events, this disparity persisted after controlling for age, other sociodemographic factors, and case mix (adjusted odds ratio 1.47; p=0.05). Analysis of potential causal factors showed no markedly or consistently different pattern between the groups.

INTERPRETATION

Despite a predominantly publicly funded hospital system, our findings suggest that hospital care received by Māori is marginally poorer than that received by New Zealand citizens of non-Māori/non-Pacific origin. Although no cause specific to Māori was evident, various policy and system issues can be addressed.

Compression, expansion, or dynamic equilibrium? The evolution of health expectancy in New Zealand

STUDY OBJECTIVE

To evaluate the New Zealand evidence for three theories of population health change: compression of morbidity, expansion of morbidity, and dynamic equilibrium.

DESIGN

Using the Sullivan method, repeated cross sectional survey information on functional limitation prevalence was combined with population mortality data and census information on the utilisation of institutional care to produce health expectancy indices for 1981 and 1996.

SETTING

The adult population of New Zealand in 1981 and 1996.

PARTICIPANTS

6891 respondents to the 1981 social indicators survey; 8262 respondents to the 1996 household disability survey.

MAIN RESULTS

As a proportion of overall life expectancy at age 15 the expectation of non-institutionalised mobility limitations increased from 3.5% to 6% for men, and from 4.5% to 8% for women; the expectation of agility limitation increased from 3% to 7.5% for men and from 4.5% to 8.5% for women, and the expectation of self care limitations increased from 2.0% to 4.5% for men and from 3.0% to 6.0% for women. These changes were primarily attributable to increases in the expectation of moderate functional limitation.

CONCLUSION

The dynamic equilibrium scenario provides the best fit to current New Zealand evidence on changes in population health. Although an aging population is likely to lead to an increase in demand for disability support services, the fiscal impact of this increase may be partially offset by a shift from major to moderate limitations, with a consequential reduction in the average levels of support required.

Maori responsiveness in health and medical research: key issues for researchers (part 1)

INTRODUCTION

Application for contestable government-research funding and ethical approval requires researchers to outline how their intended research project contributes to Maori development or advancement.

METHODS AND RESULTS

When formulating their research proposals, the key issues for researchers are research utility, defining Maori, informed consent, confidentiality, issues with human tissues and genetic material, participant remuneration and recognition (koha), intellectual property, and involvement of local Maori health or social services.

CONCLUSIONS

The most common Maori responsiveness issues in research applications can be readily approached by researchers who address straightforward methodological concerns, by working through precedents established by peers and colleagues, as well as by working with end-users of their research.

Maori responsiveness in health and medical research: clarifying the roles of the researcher and the institution (part 2)

INTRODUCTION

The combination of the Health Research Council's Guidelines for researchers on health research involving Maori and the 1998 revision of the National application form for ethical approval generated an expectation that all research development required consultation with Maori.

METHODS AND RESULTS

This paper clarifies issues of consultation for health researchers in two ways. Firstly, the historical development of the focus on the Maori research responsiveness is outlined. Secondly, we argue that research institutions, rather than researchers, need to take a lead role in consulting on research issues with Maori organisations.

CONCLUSIONS

Consultation with Maori at the institutional level could help clarify and address key ethical issues in research--while reducing the workload for researchers, Maori organisations, and host institutions alike.

The New Zealand Socio-economic Index of Occupational Status: methodological revision and imputation for missing data

OBJECTIVES

To revise and update the New Zealand Socio-economic Index (NZSEI) in the light of methodological issues in its construction, and to develop an imputation method for use where occupational information is not available.

METHODS

Data were drawn from the following New Zealand national surveys: 1996 Population Census; 1996/97 and 1997/98 Household Economic Surveys; 1996/97 Household Health Survey. Three sets of statistical analyses were applied: alternating least squares to generate socio-economic scores; cluster and discriminant function analyses to identify cut-points; and regression and logistic regression to develop and test imputation methods.

RESULTS

Socio-economic scores for the full-time workforce in 1996 showed a different distribution, but much the same occupational ordering, as in 1991. The introduction of part-time workers and income adjustment multipliers for self-employed workers significantly affected scores for management and agricultural titles. The application of cluster and discriminant function analyses generated six groupings that were relatively distinct occupationally. An imputation method based on an averaging of scores within age/qualification categories was found to achieve acceptable results.

CONCLUSIONS

Methodological improvements in the construction of the NZSEI have enhanced its empirical robustness, while a simple imputation technique has widened the potential application of the scale.

Genetics, race, ethnicity, and health

Genetics plays only a small part in ethnic differences in health, and other factors are often more amenable to change

Abdominal aortic aneurysms in the New Zealand Maori population

Background

Abdominal aortic aneurysm (AAA) is believed to be a rare disease in people of non-European descent. Maori, New Zealand's indigenous people, are thought to originate from South East Asia, so their incidence of AAA might also be expected to be low. The aim was to investigate the incidence and phenotypic factors associated with AAA in the New Zealand Maori population.

Methods

A retrospective study was performed using the audit database of the New Zealand Society of Vascular Surgeons. Age-standardized rates of admission and death were calculated for Maori and non-Maori.

Results

Maori comprised 3·9 per cent of the population who had an AAA repaired, similar to the percentage of the Maori population aged over 65 years. However, the death rate from AAA in Maori was 2·4 times the rate in non-Maori. Maori were younger at diagnosis than non-Maori (65·2 versus 71·8 years; P < 0·001), had more emergency procedures (46·6 versus 30·2 per cent; P = 0·018) and a significantly higher proportion of Maori admissions were for a ruptured aneurysm.

Conclusion

Maori had a higher mortality rate from AAA than non-Maori New Zealanders. Although admission rates between Maori and non-Maori were similar, the earlier age of onset and the increased proportion of ruptured aneurysms may indicate that the disease is more severe in Maori.

Social class mortality differences in Maori and non-Maori men aged 15-64 during the last two decades

AIMS

This investigation uses data from 1996-97 to update previous studies of social class mortality differences in Maori and non-Maori New Zealand men aged 15-64 years.

METHODS

Numerator data were obtained from the national death registrations and denominator data were from the 1976, 1986 and 1996 censi. For each social class, age standardised death rates in Maori and non-Maori men were calculated for amenable, non-amenable and all causes of mortality.

RESULTS

Maori male mortality was significantly higher than non-Maori mortality in each social class and for the total population for amenable (overall RR = 5.3(CI = 4.0-6.9)), non-amenable (overall RR = 2.4(2.2-2.6)) and all causes of mortality (overall RR = 2.4(2.3-2.6)). The social class mortality differences within Maori (relative index of inequality was 3.3) were markedly greater than non-Maori class differences (RII = 1.5).

CONCLUSIONS

The persistently high Maori mortality rates, when controlled for social class, indicate that the poor state of Maori health cannot be explained solely by relative socioeconomic disadvantage. The high Maori rate of potentially preventable deaths indicates that the health sector is still not meeting the serious health needs of many Maori. The social class mortality gradient within Maori underlines the need to address disparities within Maori.

Unlocking the numerator-denominator bias. I: Adjustments ratios by ethnicity for 1991-94 mortality data. The New Zealand Census-Mortality Study

AIM

To determine the extent of the under-reporting of Mäori and Pacific mortality among 0-74 year olds for the period 1991-94.

METHODS

A subset (n=22,578) of highly probable linked 1991 census and 1991-94 mortality records were selected from the 31,635 census-mortality links in the New Zealand Census-Mortality Study. The numbers of decedents assigned as Mäori, Pacific, and non-Mäori non-Pacific were compared between mortality and census data.

RESULTS

Compared to the death registration form, 29% more 0-74 year old decedents during 1991-94 had self-identified as sole-Mäori on the 1991 census (46% for prioritised-Mäori). This numerator-denominator bias was greater among the young and those living in central and southern New Zealand. Among 0-14, 15-24, 25-44, 45-64, and 65-74 year old decedents, respectively, 91%, 50%, 41%, 26% and 15% more decedents had self-identified as sole-Mäori on the 1991 census. For Northern, Midland, Central and Southern regional health authority areas, respectively, 14%, 17%, 81% and 102% more decedents had self-identified as sole-Mäori. Among Pacific decedents 68% more 0-74 year old decedents had self-identified as sole-Pacific on the 1991 census (78% for prioritised-Pacific group). This bias for Pacific decedents did not notably vary by age and region.

CONCLUSIONS

This study confirms substantial underestimation of Mäori and Pacific mortality rates for the period 1991-94, even using the recommended sole-ethnic group denominator. The results from this study should be used to adjust ethnic-specific mortality rates for the early 1990s. Population-based funding formulas that included region-specific Mäori mortality rates would have particularly disadvantaged central and southern regions.

Persistent social class mortality differences in New Zealand men aged 15-64: an analysis of mortality during 1995-97

OBJECTIVE

Social class mortality differences in New Zealand men aged 15-64 years have previously been examined for the periods 1975-77 and 1985-87 using the Elley-Irving social class scale. The objective was to repeat these analyses for 1995-97 in order to examine time trends, and to assess current social class patterns of mortality.

METHODS

Age-standardised mortality rates were calculated for each social class and a weighted estimate of the social class mortality gradient was obtained.

RESULTS

Male mortality declined 21% between 1985-87 and 1995-97, but the social class mortality differences have not diminished and may have even increased. The Relative Index of Inequality has increased from 1.8 in 1975-77 to 2.1 in 1985-87 and 2.3 in 1995-97. Unlike previous analyses, the relative social class mortality gradient was just as strong in the older age groups as in the younger age groups, indicating that the possible increase in social class gradient has largely occurred in the older age groups.

CONCLUSIONS

These findings indicate that the potential to address the excess preventable mortality caused by socio-economic factors has not been fully realised in New Zealand.

IMPLICATIONS

Social class analyses identify groups in the community that have an excess mortality that is potentially preventable. There are still major social class differences in mortality in New Zealand, and these differences may even have increased. It is important that these patterns are taken into account in public health planning and that further research is conducted to identify the mechanisms by which these differences occur.

Maori work-related fatal injury, 1985-1994

AIMS

To document the rate of work-related fatal injury for Maori; to establish whether a difference exists between Maori and non-Maori; and to examine possible explanations in the event that differences did occur.

METHODS

Coronial files collected as part of the examination of work-related fatal injuries occurring between 1985 and 1994, excluding motor vehicle fatalities on public roads, were reviewed. Maori were identified by either the classification recorded upon death certificates or if they were identified as Maori within coroner's files.

RESULTS

89 Maori were identified within the 741 worker fatalities. Agreement between the data sources used to identify ethnic status was approximately 52%. The crude rate for the decade was significantly higher for Maori than non-Maori. A significant linear decline across years was evident for the non-Maori rates but not for Maori rates.

CONCLUSIONS

This study, the first to specifically investigate work-related injury for Maori, confirms that an overall disparity exists between Maori and non-Maori, and that it is probably due to differences in employment patterns.

Pregnancies among New Zealand teenagers: trends, current status and international comparisons

AIMS

To examine trends in birth and total pregnancy rates among teenage women in New Zealand, ethnic differences and international comparisons.

METHODS

Routinely collected data on births and abortions by age in New Zealand have been used to derive teenage birth rates and estimated total teenage pregnancy rates.

RESULTS

The teenage birth rate rose from the end of the Second World War until 1972, then dropped until 1986, since when it has risen slightly. An increase in the proportion of teenage pregnancies aborted since 1986 has prevented a more marked increase in the birth rate. In 1997, the teenage birth rate for Maori was nearly five times, and the Pacific rate over three times, that of European/Pakeha teenagers. Although the abortion rate was slightly higher among Maori than European/Pakeha teenagers, Maori who became pregnant were much less likely to have an abortion. Of the developed OECD countries, only the USA has a higher teenage birth rate than New Zealand. However, the teenage birth rate among European/Pakeha in New Zealand, while higher than in many Western European countries, is similar to the total rate in Australia, and less than that in the UK and Canada.

CONCLUSIONS

This analysis shows that using routinely collected data, it is possible to monitor national teenage pregnancy rates. Improvements in monitoring could be made by collecting ethnicity data on abortions and births in a consistent manner, together with the area of residence of women having abortions. The findings indicate the importance of understanding the impact on Maori women who become pregnant as teenagers and on their children.