Anthropometric characteristics of Mohawk children aged 6 to 11 years: a population perspective.(Statistical Data Included)

The prevalence of type 2 diabetes mellitus is known to be markedly higher in Native North American communities compared with the general population, both in the United States (1-4) and Canada (5-9). It is also noted that type 2 diabetes is increasingly diagnosed among younger people (10). Besides genetic factors and aging, 2 modifiable lifestyle-related risk factors have been consistently and independently related to the development of type 2 diabetes: increased body fatness (11-13) and lack of physical activity (14-17). Numerous studies have documented that in Native American communities with a high prevalence of obesity among adults, there is also a high prevalence of type 2 diabetes (18-20). It has also been shown that the prevalence of obesity among Native Americans is higher than among the general population (8,21). Thus, one can argue that excess weight among Native American adults is at least partially responsible for the high prevalence of type 2 diabetes in Native American peoples.

Studies indicate that weight and obesity may track from childhood into adulthood (22-28), especially for children with one obese parent (29). Therefore, population data on Native American children's weights are valuable. Few studies have been conducted on the prevalence of excess weight among Native North American children and adolescents (30-38). Their results suggest that among Native North American populations, there is a greater proportion of overweight and obese children and a smaller proportion of underweight children than in the general American population (32-36). However, methodologic problems such as using questionnaire data for height and weight (33-36), small sample sizes (34), and collapsing age categories (35) were present in many of these studies. In addition, 2 major sources of bias were found in most of them.

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First, except for studies by Story et al (31) and Gilbert et al (37) all conclusions were based on only one anthropometric indicator: body mass index (BMI). Although BMI is viewed as a valid measure of obesity in children (39), there are limitations associated with its use. Freeman et al (40) found that the association between obesity in childhood as assessed with the BMI and obesity in adulthood varied across height categories in children. Sugarman et al (33) also reported that when skinfold thickness can be measured with high reliability, its correlation with body composition in children is higher than BMI. Furthermore, Malina (38) demonstrated that using triceps skinfold alone or BMI alone or in combination provided different estimates of ethnic variation in the prevalence of obesity.

Second, most of these studies of Native American children's anthropometry have reported data in terms of the percentage of children with BMI or weight values equal to or above a given percentile in a reference population, without further details on the general form of the population distribution of values. This emphasis on extreme values conveyed the misleading conclusion that whole populations were affected by overweight or obesity.

This study reports on Mohawk children from 2 Mohawk communities in Quebec and Ontario, Canada. The 2 communities encompass about 50% of the Mohawk population living in North America. The objectives of this study were to document the population distribution of anthropometric characteristics of Mohawk children compared with the Second National Health and Nutrition Examination Survey (NHANES II) reference population. For the Mohawk children, a variety of anthropometric indicators were used to better understand how body fat was distributed. Several analytic strategies were implemented to highlight different features of the distributions of these indicators in this population.

METHOD

Subjects

The study population consisted of all children in grades 1 to 6 (aged 6 to 11 years) attending elementary school in the 2 communities participating in the Kahnawake School Diabetes Prevention Project (KSDPP). The KSDPP is a school-based health education program embedded in a community development health promotion initiative (41,42). This project, which was launched in 1994, consisted of a 3-year intervention plan in Kahnawake and transfer of knowledge and technology to the comparison community of Tyendinaga during the third year. Data reported here were collected as baseline data for the evaluation of KSDPP in the fall of 1994.

People from the Mohawk Nation traditionally lived around the Hudson River/St-Laurent River hydrographic area, covering a territory that includes parts of upstate New York, Vermont, southwest Quebec, and …