Do differences in compositional time use explain ethnic variation in the prevalence of obesity in children? Analyses using 24-hour accelerometry.

BACKGROUND/OBJECTIVES: Whether variation in sleep and physical activity explain marked ethnic and socioeconomic disparities in childhood obesity is unclear. As time spent in one behaviour influences time spent in other behaviours across the 24-hour day, compositional analyses are essential. The aims of this study were to determine how ethnicity and socioeconomic status influence compositional time use in children, and whether differences in compositional time use explain variation in body mass index (BMI) z-score and obesity prevalence across ethnic groups. METHODS: In all, 690 children (58% European, 20% Maori, 13% Pacific, 9% Asian; 66% low-medium deprivation and 34% high deprivation) aged 6-10 years wore an ActiGraph accelerometer 24-hours a day for 5 days yielding data on sedentary time, sleep, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Height and weight were measured using standard techniques and BMI z-scores calculated. Twenty-four hour movement data were transformed into isometric log-ratio co-ordinates for multivariable regression analysis and effect sizes were back-transformed. RESULTS: European children spent more time asleep (predicted difference in minutes, 95% CI: 16.1, 7.4-24.9) and in MVPA (6.6 min, 2.4-10.4), and less time sedentary (-10.2 min, -19.8 to -0.6) and in LPA (-12.2 min, -21.0 to -3.5) than non-European children. Overall, 10% more sleep was associated with a larger difference in BMI z-score (adjusted difference, 95% CI: -0.13, -0.25 to -0.01) than 10% more MVPA (-0.06, -0.09 to -0.03). Compositional time use explained 35% of the increased risk of obesity in Pacific compared with European children after adjustment for age, sex, deprivation and diet, but only 9% in Maori and 24% in Asian children. CONCLUSIONS: Ethnic differences in compositional time use explain a relatively small proportion of the ethnic differences in obesity prevalence that exist in children.

Ethnic and socioeconomic inequalities in dental treatment at a school of dentistry.

BACKGROUND AND OBJECTIVES: Health services should be targeted toward those most in need of health care. Poor oral health disproportionately affects Maori, Pacific Island, and socioeconomically deprived New Zealanders of all ages, and oral health care services should be prioritised to such groups. In New Zealand, free oral health care is available for all children up to the age of 17. On the other hand, adult dental services are provided on a user-pays basis, except for a limited range of basic services for some adults, access to which varies regionally. This study investigated the extent of dental treatment inequalities among patients at New Zealand's only School of Dentistry. METHODS: Data were audited for all treatments provided at the University of Otago Faculty of Dentistry from 2006 to 2011 for patients born prior to 1990. Ethnic and socioeconomic inequalities in the provision of dental extractions, endodontic treatment, crowns, and preventive care were investigated. Differences were expressed as the odds of having received one or more treatments of that type during the six-year period 2006 to 2011. RESULTS: Data were analysed for 23,799 individuals, of whom 11,945 (50.2%) were female, 1,285 (5.4%) were Maori and 479 (2.0%) were Pacific, 4,040 (17.0%) were of low socioeconomic status (SES), and 2,681 (11.3%) were beneficiaries or unemployed. After controlling for SES, age, and sex, Maori had 1.8 times greater odds of having had a tooth extracted than NZ European patients, while Pacific Islanders had 2.1 times the odds. Furthermore, after controlling for ethnicity, age, and sex, low-SES patients had 2.4 times greater odds of having had a tooth extracted than high-SES patients, and beneficiaries had 2.9 times the odds. Conversely, these groups were less likely to have had a tooth treated with a crown or endodontics or receive preventive care. CONCLUSIONS: Existing policies call for the reduction of inequalities. There is a need for a strategy to monitor changes in treatment inequality over time which includes improving equity in service care provision. The observed treatment inequalities are likely to be an underestimate of those occurring in private dental practice in New Zealand.

Glycaemic responses to glucose and rice in people of Chinese and European ethnicity.

AIMS: Diabetes rates are especially high in China. Risk of Type 2 diabetes increases with high intakes of white rice, a staple food of Chinese people. Ethnic differences in postprandial glycaemia have been reported. We compared glycaemic responses to glucose and five rice varieties in people of European and Chinese ethnicity and examined possible determinants of ethnic differences in postprandial glycaemia. METHODS: Self-identified Chinese (n = 32) and European (n = 31) healthy volunteers attended on eight occasions for studies following ingestion of glucose and jasmine, basmati, brown, Doongara(®) and parboiled rice. In addition to measuring glycaemic response, we investigated physical activity levels, extent of chewing of rice and salivary α-amylase activity to determine whether these measures explained any differences in postprandial glycaemia. RESULTS: Glycaemic response, measured by incremental area under the glucose curve, was over 60% greater for the five rice varieties (P < 0.001) and 39% greater for glucose (P < 0.004) amongst Chinese compared with Europeans. The calculated glycaemic index was approximately 20% greater for rice varieties other than basmati (P = 0.01 to 0.05). Ethnicity [adjusted risk ratio 1.4 (1.2-1.8) P < 0.001] and rice variety were the only important determinants of incremental area under the glucose curve. CONCLUSIONS: Glycaemic responses following ingestion of glucose and several rice varieties are appreciably greater in Chinese compared with Europeans, suggesting the need to review recommendations regarding dietary carbohydrate amongst rice-eating populations at high risk of diabetes.