Higher prevalence of left ventricular hypertrophy in two Māori cohorts: findings from the Hauora Manawa/Community Heart Study

Objectives: Cardiovascular disease (CVD) is the leading cause of mortality in New Zealand with a disproportionate burden of disease in the Māori population. The Hauora Manawa Project investigated the prevalence of cardiovascular risk factors and CVD in randomly selected Māori and non‐Māori participants. This paper reports the prevalence of structural changes in the heart. Methods: A total of 252 rural Māori, 243 urban Māori; and 256 urban non‐Māori underwent echocardiography to assess cardiac structure and function. Multivariable logistic regression was used to determine variables associated with heart size. Results: Left ventricular (LV) mass measurements were largest in the rural Māori cohort (183.5,sd 61.4), intermediate in the urban Māori cohort (169.7,sd 57.1) and smallest in the non‐Māori cohort (152.6,sd 46.7; p<0.001). Similar patterns were observed for other measurements and indexation had no impact. One‐third (32.3%) met the gender‐based ASE criteria for LV hypertrophy (LVH) with higher prevalence in both Maori cohorts (highest in the rural cohort). There were three significant predictors of LVH: rural Māori (p=0.0001); age (p<0.0001); and gender (p=0.0048). Conclusion: Structural and functional heart abnormalities are more prevalent in Māori compared to non‐Māori, and especially rural Māori. Early identification should lead to better management, ultimately improving life expectancy and quality of life.     

Disparities in indigenous health: a cross-country comparison between New Zealand and the United States

OBJECTIVES: We compared the health statuses of the indigenous populations of New Zealand and the United States with those of the numerically dominant populations of these countries. METHODS: Health indicators compared included health outcome measures, preventive care measures, modifiable risk factor prevalence, and treatment measures. RESULTS: In the case of nearly every health status indicator assessed, disparities (both absolute and relative) were more pronounced for Maoris than for American Indians/Alaska Natives. Both indigenous populations suffered from disparities across a range of health indicators. However, no disparities were observed for American Indians/Alaska Natives in regard to immunization coverage. CONCLUSIONS: Ethnic health disparities appear to be more pronounced in New Zealand than in the United States. These disparities are not necessarily intractable. Although differences in national health sector responses exist, New Zealand may be well placed in the future to evaluate the effectiveness of new strategies to reduce these disparities given the extent and quality of Maori-specific health information available.     

Follow-up methods for retrospective cohort studies in New Zealand

OBJECTIVES: To define a general methodology for maximising the success of follow-up processes for retrospective cohort studies in New Zealand, and to illustrate an approach to developing country-specific follow-up methodologies. METHODS: We recently conducted a cohort study of mortality and cancer incidence in New Zealand professional fire fighters. A number of methods were used to trace vital status, including matching with records of the New Zealand Health Information Service (NZHIS), pension records of Work and Income New Zealand (WINZ), and electronic electoral rolls. Non-electronic methods included use of paper electoral rolls and the records of the Registrar of Births Deaths and Marriages. RESULTS: 95% of the theoretical person-years of follow-up of the cohort were traced using these methods. In terms of numbers of cohort members traced to end of follow-up, the most useful tracing methods were fire fighter employment records, the NZHIS, WINZ, and the electronic electoral rolls. CONCLUSIONS: The follow-up process used for the cohort study was highly successful. On the basis of this experience, we propose a generic, but flexible, model for follow-up of retrospective cohort studies in New Zealand. Similar models could be constructed for other countries. IMPLICATIONS: Successful follow-up of cohort studies is possible in New Zealand using established methods. This should encourage the use of cohort studies for the investigation of epidemiological issues. Similar models for follow-up processes could be constructed for other countries.     

Follow-up methods for retrospective cohort studies in New Zealand

Objectives: To define a general methodology for maximising the success of follow-up processes for retrospective cohort studies in New Zealand, and to illustrate an approach to developing country-specific follow-up methodologies.
Methods: We recently conducted a cohort study of mortality and cancer incidence in New Zealand professional fire fighters. A number of methods were used to trace vital status, including matching with records of the New Zealand Health Information Service (NZHIS), pension records of Work and Income New Zealand (WINZ), and electronic electoral rolls. Non-electronic methods included use of paper electoral rolls and the records of the Registrar of Births Deaths and Marriages.
Results: 95% of the theoretical person-years of follow-up of the cohort were traced using these methods. In terms of numbers of cohort members traced to end of follow-up, the most useful tracing methods were fire fighter employment records, the NZHIS, WINZ, and the electronic electoral rolls.
Conclusions: The follow-up process used for the cohort study was highly successful. On the basis of this experience, we propose a generic, but flexible, model for follow-up of retrospective cohort studies in New Zealand. Similar models could be constructed for other countries.
Implications: Successful follow-up of cohort studies is possible in New Zealand using established methods. This should encourage the use of cohort studies for the investigation of epidemiological issues. Similar models for follow-up processes could be constructed for other countries.     

How much does health care contribute to health inequality in New Zealand?

OBJECTIVE: To quantify the contribution of health care to ethnic and socio-economic inequalities in health in New Zealand in 2000-02, using the concept of 'amenable' mortality (deaths at ages 0-74 years from causes responsive to health care). DATA SOURCES AND METHODS: Mortality data for 2000-02 were provided by the New Zealand Health Information Service and 2001 Census population data were provided by Statistics New Zealand. The classification of ICD-10 codes as amenable or non-amenable used in the Australian and New Zealand Atlas of Avoidable Mortality (2006) was adopted. Ethnicity was categorised as Maori, Pacific or European/Other. Socio-economic position was measured using a Census-based small area deprivation index, the NZDep2001. Mortality rates were standardised for age by the direct method for the ethnic group comparisons, and for both age and ethnicity for the deprivation group comparisons. The contribution of health care to health inequality was then quantified as the ratio of the difference in standardised amenable mortality rates to the difference in standardised total mortality rates (in the age group 0-74 years) between relevant groups. RESULTS: Amenable causes of death were estimated to account for 27%, 34%, 33% and 44% of the total mortality disparity (0-74 years) for Maori males, Maori females, Pacific males and Pacific females respectively, relative to their European/ Other counterparts (adjusting for age). The corresponding proportions for the 'deprived' population relative to the 'non-deprived' population were 26% (males) and 30% (females), adjusting for age and ethnicity. CONCLUSIONS: Amenable causes of death made a substantial contribution to differences in mortality in the 0-74 year age range between ethnic and socio-economic groups in New Zealand in 2000-02, ranging from 26-44% depending on the group.     

The Older Persons' Index of Multiple Deprivation: Measuring the deprivation circumstances of older populations in Aotearoa New Zealand

Existing indices of multiple deprivation exclude indicators specifically relevant to the population aged ≥65 years. In this study we create a whole-of-population cohort of people aged ≥65 years living in private dwellings and who completed the 2013 New Zealand Census of Populations and Dwellings to create an Older Persons' Index of Multiple Deprivation (OPIMD). We combined 22 indicators representing 6 domains of deprivation (Income, Housing, Health, Assets, Connectedness and Geographic access) to establish this individual-level measure of deprivation. We used smoking data from the census to validate the OPIMD and describe the geography of the OPIMD by District Health Board, contrasting these patterns with a conventional area deprivation index. The OPIMD has the potential to inform policies concerning resource allocation for the older population. An accompanying website with an interactive atlas and an online OPIMD calculator is available for wider use of the data. Further research is required to explore associations between the OPIMD and other major health and social outcomes affecting this population.     

Challenges in comparing the methods and findings of cohort studies of oral health: the Dunedin (New Zealand) and Pelotas (Brazil) studies

Objective: to systematically compare methods and some findings from two prospective cohort studies of oral health. Methods : This paper describes and compares two such population‐based birth cohort studies of younger adults: the Dunedin Multidisciplinary Health and Development Study (conducted in New Zealand); and the 1982 Pelotas Birth Cohort Study (conducted in Brazil). Results: The two cohorts showed socio‐demographic similarities and differences, with their gender mixes being similar, but their ethnic compositions differing markedly. There were some important similarities and differences in methods. Overall dental caries experience was higher among the Dunedin cohort. Each of the studies has examined the association between childhood‐adulthood changes in socio‐economic status and oral health in the mid‐20s. Both studies observed the greatest disease experience among those who were of low SES in both childhood and adulthood, and the least among those who were of high SES in both childhood and adulthood. In each cohort, disease experience in the upwardly mobile and downwardly mobile groups lay between those two extremes. Conclusions and implications: There are important similarities and differences in both methods and findings. While the need for a degree of methodological convergence in future is noted, the two studies are able to use each other as replicate samples for research into chronic oral conditions.     

Did it fall or was it pushed? The contribution of trends in established risk factors to the decline in premature coronary heart disease mortality in New Zealand

OBJECTIVE: To estimate the contribution of trends in three risk factors--systolic blood pressure (SBP), total blood cholesterol (TBC) and cigarette smoking--to the decline in premature coronary heart disease (CHD) mortality in New Zealand from 1980-2004. METHOD: Risk factor prevalence data by 10-year age group (35-64 years) and sex was sourced from six national or Auckland regional health surveys and three population censuses (the latter only for smoking). The data were smoothed using two-point moving averages, then further smoothed by fitting quadratic regression equations (SBP and TBC) or splines (smoking). Risk factor/CHD mortality hazard ratios estimated by expert working groups for the World Health Organization Global Burden of Disease Study 2001 were used to translate average annual changes in risk factor prevalences to the corresponding percentage changes in premature CHD mortality. The expected trends in CHD mortality were then compared with the observed trend to estimate the contribution of each risk factor to the decline. FINDINGS: Approximately 80% (73% for males, 87% for females) of the decline in premature CHD mortality from 1980 to 2004 is estimated to have resulted from the joint trends in population SBP and TBC distributions and smoking prevalence. Overall, approximately 42%, 36% and 22% of the joint risk factor effect was contributed by trends in SBP, TBC and smoking respectively. CONCLUSION: Our estimate for the joint risk factor contribution to the CHD mortality decline of 80% exceeds those of two earlier New Zealand studies, but agrees closely with a similar Australian study. This provides an indicator of the scope that still remains for further reduction in CHD mortality through primary and secondary prevention.     

From secondary prevention to primary prevention: a unique strategy that gives hope to a country ravaged by meningococcal disease

New Zealand has been affected by an epidemic of group B meningococcal disease dominated by a strain defined as, B:4:P1.7b,4. Over 5550 cases and 222 deaths have been reported since 1991 in a population of 4 million people.Meningococcal disease cases notified on EpiServ database operated by Institute of Environmental Science and Research Limited through to 30 September 2004. Through the collaborative efforts of a government agency, vaccine company, university and laboratory institute, clinical trials of the Chiron produced outer membrane vesicle (OMV) strain-specific MeNZB vaccine were run in rapid succession. The delivery of MeNZB will be New Zealand's largest immunisation programme with three doses given at 6-week intervals to over 1 million people aged 6 weeks-19 year olds inclusive. Planning, co-ordinating and delivering the immunisation programme is a challenging project for the New Zealand Health Sector.