Māori Health Review Issue 9

This article appraises the evidence for the the thrifty gene hypothesis. The authors highlight the fact that when population genetic data are used to map susceptibility for complex disease, the research is seen as commendable; embracing the goals of disease prevention and harm reduction for all, especially dispossessed, formerly enslaved, or colonised populations. Thus, genetic research into complex disease attracts a high investment of scientific resources, yet such research fails to greatly enhance our understanding about these diseases and it maintains problematic conceptions of human variation. The authors point out that although population genetic data may seemingly support the contention that the high prevalence of type 2 diabetes mellitus is due to our biological incapacity to cope with modern affluent and sedentary lifestyles, no consistent evidence supports the notion that minority populations are particularly genetically susceptible. Further, they note that it is unclear as to why such genetic differences should exist, given the original pan-species orientation of the thrifty gene hypothesis. Genetic research into complex disease should pay close attention to key environmental, social, and genetic risk factors operating within and between groups, and not simplistically attribute between-group differences to racialised genetics.

Plasma 25-hydroxyvitamin D (25[OH]D), total calcium (CaT), ionised calcium (CaI) and parathyroid hormone (PTH) concentrations in healthy volunteers (11 9 female, 82 male; median age 45 years), measured between February and July 2004, were modelled in a relationship with vitamin D-weighted ultraviolet (UV) energy measurements (dUV) for Christchurch, obtained from the National Institute of Water and Atmospheric Research UV Atlas. 25(OH)D levels were <75 nmol/L in 88% of subjects in February 2004 and in 100% of subjects in June and July. Levels were severely deficient (<12.5 nmol/L) in 1.5% of subjects. Between February and July, there were significant decreases in 25(OH)D and CaI concentrations and a significant increase in the CaT concentration. There was a hyperbolic relationship between PTH and 25(OH)D while CaT and CaI correlated negatively with PTH (r = -0.30 and -0.33; both p<0.001). Monthly mean dUV intensity ranged from 10 kJ∙m-2∙day-1 in December 2003 to 0.5 kJ∙m-2∙day-1 in June 2004. Compartmental modelling estimated that a Christchurch person made 1200 IU/day of vitamin D in mid-summer but only 60 IU/day in midwinter. The authors suggest that a daily supplement of 2600 IU vitamin D3 would correct vitamin D deficiency.

New Zealand cardiovascular (CVD) risk management guidelines support targeted treatment to patients with a high 5-year CVD risk and recommend a 5% upward adjustment for some high-risk population subgroups. This study estimated the impact of these adjustments on eligibility for treatment in a primary care setting, using data from CVD risk assessments involving 23,709 patients visiting their primary care provider in Auckland, New Zealand, between 2002 and 2006. Baseline CVD risks were calculated with and without the 5% upward adjustment for family history of premature ischaemic CVD or for being of Mäori, Pacific or Indian subcontinent ethnicity. Baseline CVD risks were calculated for 23,693 patients (99.9%); 90% were aged between 35 and 74 years. Unadjusted risk scores revealed that 70% of patients were below the 10% 5-year risk threshold for specific individualised treatment; 11 % were between the 10 to 15% risk (recommended to receive individualised lifestyle counselling in general practice) and 19% had a >15% risk (recommended for drug treatment and referral to a dietician in addition to individualised lifestyle counselling). Over 25% of patients had a premature family history of CVD; 21% were Mäori, Pacific, or Indian subcontinent – adjusted risk scores increased the numbers eligible for drug treatment, intensive lifestyle management, and dietician referral by approximately 20% and individualised lifestyle assessment and counselling by 50%.

This worldwide study sought to determine the prevalence of chronic obstructive pulmonary disease (COPD) and its risk factors and investigate variation across countries by age, sex, and smoking status. A total of 9,425 participants completed postbronchodilator spirometry testing plus questionnaires about respiratory symptoms, health status, and exposure to COPD risk factors. COPD prevalence estimates based on the Global Initiative for Chronic Obstructive Lung Disease staging criteria were adjusted for the target population. Overall, 10.1% had stage II or higher COPD; gender-specific rates were 11· 8% for men and 8·5% for women. Odds ratios (ORs) for 10-year age increments did not vary greatly across sites and for women and men. The overall pooled estimate was 1· 94 (95% CI 1· 80 to 2·1 0) per 10-year increment. Sitespecific pack-year ORs varied significantly in women (pooled OR=1· 28, 95% CI 1·1 5 to 1· 42), but not in men (1·1 6, 1·1 2 to 1· 21). The authors note that while age and smoking are recognised as strong contributors to COPD, they fail to fully explain variations in disease prevalence; local public health officials must better appreciate what other factors contribute to COPD, in order to develop appropriate, region-specific primary and secondary prevention policies.

This randomised controlled trial investigated whether antenatal breastfeeding education alone or postnatal lactation support alone improves rates of exclusive breastfeeding compared with routine hospital care. Participants comprised 450 women with uncomplicated pregnancies at a tertiary hospital in Singapore. Compared with women who received routine care, women receiving antenatal education were much more likely to breastfeed exclusively at six weeks, three months, and six months postnatally; women in the postnatal support group were more likely to breastfeed exclusively at two weeks, six weeks, three months, and six months postnatally. The numbers needed to treat to achieve one woman exclusively breast feeding at six months were 11 for postnatal support and 10 for antenatal education. In conclusion, hospital-based interventions comprising antenatal breastfeeding education and postnatal lactation support significantly improve rates of exclusive breastfeeding up to six months after delivery.

This study investigated racial disparities in asthma management and outcomes in a managed care organisation that provided uniform access to health care services. It prospectively studied 678 patients and interviewed after discharge all patients who had been hospitalised for asthma. Patients were followed-up for subsequent emergency room visits and hospitalisations during a median follow-up of 1.9 years. Black patients had almost double the risk of emergency room visits (hazard ratio 1.93) and hospitalisations (HR 1.89) compared with White patients. The differences persisted after adjustment for socioeconomic status and differences in asthma therapy. Because all patients had uniform access to care, the authors said the findings support the potential for genetic differences related to asthma.

In this study, ethnically diverse, low-income (n=193) and middle-class women (n=146) were questioned about their pregnancy-related health care experiences. The main aim of the study was to examine whether health care providers are perceived as advising low-income women, particularly women of colour, to limit their childbearing and to what extent they feel they are discouraged by providers from having future children. According to logistic regression analyses, the odds of being advised to limit childbearing were greater for low-income women of colour than for middle-class White women. In a separate statistical analysis, the odds of being discouraged from having children were greater for low-income Latinas than for middle-class White women. The study authors conclude that more research is needed to assess how ethnicity and social class impact women’s experiences with reproductive health care.

This US-based study examined the relationship between smoking participation and cigarette pack price by income group and time period to determine the role of cigarette prices in income-related disparities in smoking. Data from the 1984–2004 Behavioral Risk Factor Surveillance System surveys were linked to information on cigarette prices to examine the adjusted prevalence of smoking participation and smoking participation–cigarette pack price elasticity (change in percentage of persons smoking relative to a 1% change in cigarette price) by income group (lowest income quartile [lower] vs all other quartiles [higher]) and time period (before vs after the Master Settlement Agreement [MSA]). Overall, the study found that the increasing price of cigarettes over time was associated with a marked decline in smoking for higher-income individuals, but not for lower-income persons. Prior to the MSA, the association between cigarette pack price and smoking participation revealed a significantly larger elasticity among lowerversus higher-income persons (–0.45 vs –0.22). After the MSA, the association was not statistically significant for either income group. The authors conclude that “despite cigarette price increases after the MSA, income-related smoking disparities have increased”. Cigarette prices are no longer an effective strategy to reduce smoking prevalence and may impose a disproportionate burden on poor smokers.

Hauora IV: Maori Health Standards 1990 to 2005 The launch for this important document is planned for the end of November 2007. The latest ‘Hauora’ book has up to date Mäori health data for all major causes of mortality and hospitalisations, and particular topics of interest including racism in health; mental health issues; Mäori and disability; and chapters dedicated to specific illnesses including cancer, respiratory and cardiovascular disease. I hope to bring you summaries of the chapters and their website links in future issues of Mäori Health Review.
INIHKD October 2007 Commentaries for this issue were written during breaks of the INIHKD conference held in Rotorua. It was a pleasure to catch up with friends and colleagues from around the motu and from overseas. For those of you who couldn’t make it, I plan to provide summaries and comments of some of the presentations at the conference including: • Applying ethical standards to front line service delivery in Canadian Indigenous communities • Tribal and urban American Indian/Alaska Native epidemiology centres • Indigenising community-based participatory research • Pukapuka Hauora: Mäori parents’ experience of managing a child with asthma • Manaaki Manawa; cardiac rehabilitation developed by Mäori for Mäori.