Abstract

This paper presents the methodology used in a prevalence study of non-insulin-dependent diabetes mellitus (NIDDM) among native Canadians living in an isolated northwestern Ontario community. Volunteers aged 10 and older were screened using a 75-g oral glucose tolerance test in accordance with the World Health Organization's criteria. Interviewer-administered questionnaires were used to collect information on demographics, current and historical physical activity, diet, family history of diabetes and health knowledge. Anthropometric measurements included body mass index, waist-to-hip ratio and percent body fat from bioelectrical impedance analysis. Fitness level was assessed using a three-stage step test. Participation and community response were excellent, and this can be attributed in large part to the partnership that was established between the researchers and the community, and the employment of local people as recruiters and interviewers. The many valuable lessons learned during the process are discussed.

Key words: Aboriginal health; diabetes mellitus, non-insulin-dependent; diet; exercise; family history; obesity; Ontario; prevalence; risk factors

Introduction

Study Objectives
The three major objectives of the Sandy Lake Health and Diabetes Project (SLHDP) were the following.

• To determine the true prevalence of NIDDM and impaired glucose tolerance (IGT) in an isolated aboriginal community in northern Ontario
• To identify anthropometric, metabolic and lifestyle characteristics associated with NIDDM and IGT in the community
• To use ethnographic data collection techniques to aid in the development of culturally appropriate data collection instruments and intervention strategies to modify risk factors for diabetes and its complications

This partnership and co-operative relationship was not only ethically necessary, it was beneficial in promoting the project in the community. Council members were among the first volunteers surveyed, which helped to confirm the leaders' endorsement of the project in the eyes of community members.

Ethical Approval
The proposal for this project was approved by the University of Toronto Research Ethics Committee.

Methods

The community is isolated, accessible only by air for most of the year, except for a winter road open for about six weeks in January and February.

Health care is delivered at a nursing station operated by the federal government and staffed by six specially trained outpost nurses.

Historically, the people of this region led a hunting-gathering life in small, extended family groups typical of other subarctic peoples. Their lifestyle was extremely physically active, and their diet was high in protein from wild meats, with seasonal supplementation from berries and roots. With the development of the Indian reserve and residential school systems, the traditional lifestyle was eroded and a welfare economy emerged with its accompanying social consequences. Notably, the primary source of food changed during this period from wildlife to the Hudson Bay Company store (now known as the Northern).

Time Line
Data collection for the SLHDP occurred between July 1993 and March 1995.

Ethnographic Component
Beginning in January 1992 (18 months prior to the beginning of the epidemiologic survey), a medical anthropologist worked with a local assistant collecting ethnographic information on health beliefs and attitudes, perceptions of food and physical activity, notions of disease causation and opinions on the determinants of health and disease prevention.5 This information was used extensively in study design and questionnaire development. The ethnographic data collection is ongoing and is currently being used to aid in the development of a community-based intervention strategy.6

Project Logistics and Staffing in Sandy Lake
A rental community house served as the study centre as well as the residence for the project co-ordinator. This building came to be known in the community as the "Project House"; its existence helped to facilitate local acceptance of the study. An administrative office was also maintained at the nursing station. The -70 degree C freezer was located there, connected to the building's backup generator.

Sandy Lake project staff consisted of five community surveyors and an epidemiologist/project co-ordinator. The surveyors were community members hired to recruit volunteers and to administer the data collection instruments. All surveyors were native women able to speak, read and write English and to speak Oji-Cree. One surveyor was also able to read and write syllabics, the system of phonetic symbols used by most of the older people in the community.

Training
During May and June 1993, an intensive staff training program provided detailed instruction in each of the data collection instruments and techniques, as well as guidance in proper questionnaire administration and assurance of confidentiality. Progress was assessed regularly using written tests and supervised role-playing. Reliability was assured using standardization exercises, such as multiple recording of sample interviews and review of inter-surveyor variability. At the end of the training period, the surveyors received a final assessment and were presented with diplomas documenting their certification as trained community surveyors.

Project Promotion
In the spring and summer of 1993, project team members organized programs that were aired on local radio and television describing the project's objectives and future activities. The programs were presented in both English and Oji-Cree, and community members were invited to phone in with questions.

Additional promotion occurred at community social and cultural events. An information booth was set up at "Treaty Days," an annual event held at the community fairground. Information was posted in English and syllabics, and project fact sheets were distributed. This booth was well received, and a large number of people stopped to read the materials and ask questions.

Perhaps the most successful promotional approach was via "word of mouth." In small, closely-knit communities, information is usually communicated in this way. The surveyors discussed their roles and the project's objectives with their friends and extended families.

Promotional activities continued throughout the period of data collection.

Subject Recruitment, Eligibility and Consent
Eligibility criteria for the SLHDP are illustrated in Figure 1. The recruiting objective was to enrol all eligible members of the Sandy Lake community. Individuals were considered eligible if they were registered members of the Sandy Lake Band and had lived in Sandy Lake for at least six months of the past year. Registered members of other bands who were living in the households of Sandy Lake Band members were also included. Students meeting the above criteria who were attending institutions outside of the community were enrolled when they returned home for holidays.

The unit of recruitment was the household. Four strategies were required to organize recruitment and track participation.

• Identification of eligible individuals from the band list The federal Department of Indian Affairs and Northern Development maintains lists of registered Indians by band and household grouping. At the beginning of the survey, the Sandy Lake Band Office provided a copy of the most recent band list. Names of community members who had participated in the survey were highlighted; notation was made beside names of individuals who were ineligible or refused to participate. This was the most effective method of identifying eligible Sandy Lake Band members.
• Identification of eligible households using a community map A large, detailed surveyor's map was obtained from an engineering firm that was working in the community. Houses were marked on this map, and it was postulated that this would allow for the systematic recruitment of households by neighbourhood. The strategy was initially effective; however, the map was produced prior to the beginning of water and sewer construction, and the surveyors discovered that a number of houses had since been moved or erected as a result of this activity. Despite these limitations, the map continued to be a useful (although not a primary) recruiting and tracking instrument.
• Identification of eligible individuals using the household demographics questionnaire Part I of the household interview questionnaire (see below) collected information about household membership and demographics. This information allowed for the identification of individuals who did not participate in the survey with the rest of their household. The strategy proved to be very effective, especially during follow-up recruitment toward the end of the survey and especially with registered members of other bands living in Sandy Lake households.
• Use of the surveyors' local knowledge The surveyors were all locally born, and the majority had lived in Sandy Lake their entire lives. In their collective experience and knowledge, there was thorough familiarity with family and household membership in the community. The surveyors used this knowledge in conjunction with the sources listed above to recruit eligible individuals systematically as well as opportunistically (e.g. while shopping or visiting friends). This local knowledge was unequivocally the most important recruiting and tracking resource.

Compliance with these requests was quite high, although a few volunteers (approximately 5%) did not remember to fast for their first scheduled visit date. These individuals were requested to return the next day after fasting. Often "wake-up calls" (by telephoning or visiting) were needed also for volunteers who had agreed to attend.

Volunteers aged 10 and older performed the full screening, anthropometry and questionnaire protocol. Data collection on children under 10 consisted of anthropometric measurements only (see below).

Participation
Seventy-six percent (1062/1401) of the total eligible population participated in the SLHDP; the rate was slightly lower (72%; 729/1019) in the screened subgroup aged 10 and older (see Figure 1.)

Age and sex characteristics of participants and non-participants (refusals) appear in Table 1. The age structures of the participants and non-participants were similar, both being skewed toward the younger age groups, as would be expected given the age structure of the general population. More men than women refused to participate, with the highest rate of non-participation occurring among males aged 40-49. Project staff were unable to clearly identify determinants of non-participation in this latter group, although it appeared that these men were more likely to be working full time. It also seemed that they were more likely to volunteer if they attended with their families or girlfriends.

Prevalence Screening and Blood Analysis
Volunteers were asked to arrive at the Project House between 08:30 and 09:30 after an 8-12 hour overnight fast. Study identification numbers were assigned to each volunteer. Fasting blood samples for plasma glucose, insulin, C-peptide, creatinine and urea, and serum lipid and lipoprotein analyses were collected in Vacutainer tubes and processed on site.

A standard 75-g oral glucose tolerance test (OGTT) (Glucodex, Rougier Inc., Chambly, Quebec) was then administered and a second blood sample for glucose collected after 120 minutes. Volunteers were excluded from the OGTT if they had physician-diagnosed diabetes and were currently being treated with insulin or an oral hypoglycemic agent (verified by nursing station chart review), or if they had physician-diagnosed diabetes and a fasting blood sugar of >11.1 mmol/L. Children aged 10-18 received 1.75 g of glucose per kg of body weight to a maximum of 75 g. Volunteers who were pregnant at the time of recruitment were temporarily excluded and contacted again three months postpartum.

NIDDM and IGT were diagnosed as per World Health Organization criteria.7 Volunteers who tested positive for NIDDM were informed in person by project staff and were referred to the nursing station and the diabetes education program. Those who tested positive for IGT were told they were at increased risk for NIDDM and were advised to make preventive lifestyle changes. Those with normal levels were informed via a hand-delivered letter.

Plasma for glucose, creatinine and urea was shipped to the Sioux Lookout Zone Hospital laboratory. Glucose, creatinine and urea levels were determined using standard clinical laboratory methods. Samples were also shipped to the Banting and Best Diabetes Centre Core Lab in Toronto for determination of plasma insulin and C-peptide levels by radio-immunoassay.

Serum for lipid and lipoprotein analyses was analyzed at the University of Toronto Lipid Research Laboratory. Levels of total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, apolipoprotein AI and B, and lipoprotein (a) were measured using procedures as described in the Lipid Research Clinics' Manual of Laboratory Operations.8

Questionnaires
The various sections of the multicomponent questionnaires were developed by the project team or adapted from published sources and customized to the Sandy Lake setting (see below). Both processes made extensive use of information accumulated during the ethnographic fieldwork.5 Drafts of the questionnaires were translated into Oji-Cree (both phonetics and syllabics) and field tested by the surveyors in various segments of the population. When necessary, sections of the forms were adjusted and pre-tested again.

The local pre-testing exercises were very beneficial in making the questionnaire user-friendly for the surveyors and for the volunteers. The process also gave the surveyors a sense of ownership of the instruments.

Questionnaires were administered by the surveyors in English or Oji-Cree, depending on the preference of the respondent. Completed questionnaires were checked by the senior surveyor and the project co-ordinator. Errors and missing data were followed up on the telephone or during home visits.

Household questionnaire
The household questionnaire was administered in the home to an adult member of the household. Originally, the interview was intended to occur the evening before the family was to visit the Project House. However, it turned out that this was often not feasible given the busy schedules of surveyors and volunteers. Many of these interviews were conducted toward the end of the survey period.

The household questionnaire consisted of questions on household membership, household socio-economic status (SES) and household food preparation.

The household membership form was designed as a method of establishing the primary (usual) residences of community members and ensuring that all members of given households had been recruited. It was also an alternative system of tracking community participation. Study identification number, date of birth and relationship to the head of the household were recorded, with head of household usually considered the father or grandfather, or alternatively the mother or grandmother.

The household SES form was specially designed to assess socio-economic status in the absence of standard indicators (e.g. salary scale, home ownership). The questionnaire collects information on the household members' ownership of various material goods (both working and broken), such as cars, skidoos, stereos and television sets. Other indirect indicators of influence and status were measured, such as the age and square footage of the house, the number of added rooms and the presence of an outdoor washroom. This information is being used to construct quantitative scales of SES, using Guttman scaling techniques.9

The household food preparation form was designed to collect information on the use of fat in food preparation. For 13 commonly consumed foods, the respondent was queried on method of preparation (e.g. fried, baked), kind of fat used in preparation and the kind of fat eaten on or with the food after preparation.

The interview duration for the household questionnaire was 15-30 minutes, and the questions were generally well received, although some volunteers expressed puzzlement at the presence of SES questions in a diabetes survey.

Individual risk factor questionnaire
The individual risk factor questionnaire was administered at the Project House to volunteers in the interval between fasting and two-hour blood sampling. Demographic information was collected, including gender, date of birth, marital status, education, and current and past occupations. Additional demographic information specific to the Sandy Lake setting was collected, such as band number, frequency of travel outside the community and languages spoken.

Historical (four age categories), past year and current levels of occupational and leisure-time physical activity were determined using a modified version of an instrument developed and validated by Kriska and colleagues for assessing physical activity in the prospective Pima Indian study in Arizona.10 Adjustments were made in the list of activities to account for cultural differences between southwestern and subarctic native peoples (e.g. dog sledding replaced horseback riding).

A series of questions assessed the volunteer's knowledge and beliefs regarding the causes and consequences of diabetes and the nutritional benefits of foods and food preparation. From a series of somatotype drawings,11 volunteers were asked to identify their own body build and to select the most healthy somatotype for both men and women.

Two instruments were used to assess diet: a 24-hour dietary recall and a food frequency questionnaire. In the first case, volunteers were asked to report all foods consumed during the past 24 hours. They were prompted to include added fat, sugar, snacks, etc., and they were assisted in recalling portion sizes using measuring cups and spoons, three-dimensional rubber food models and a set of validated two-dimensional models.12 Recipes were collected from the preparer for traditional dishes and multi-ingredient items such as stews and soups. Copies of completed 24-hour recalls were sent for coding to the Department of Nutritional Sciences at the University of Toronto.

In the food frequency questionnaire, volunteers were asked to report the frequency of consumption over the previous three months of 34 commonly eaten foods. Traditional foods such as moose, duck, fish, rabbit and wild berries were listed along with available store-bought meats, fruit, vegetables, canned and frozen goods, and snack foods. For each item, the respondent was also asked whether his or her consumption varied by season. Additional questions inquired about added sugar and salt, types of soft drinks consumed (diet or regular), and meal and snack frequency.

Information was collected on lifetime tobacco use and current exposure to sidestream smoke (yes/no). Current smokers were asked about duration of smoking (in years) and number of cigarettes per day. Former smokers were asked about duration of smoking and time since cessation.

Volunteers were asked how often they drank alcohol (four categories) and how much they consumed of beer (12-oz bottles), wine (6-oz glasses) and liquor (1.5-oz shots). They were also asked if they had drunk at least one alcoholic beverage per week over the previous year or if they had ever consumed at least one alcoholic beverage per week for more than one year.

Family history of diabetes was assessed by inquiring about the presence of diabetes in biological first-degree relatives (parents, grandparents, siblings and offspring). Diabetes status of half-siblings, if applicable, was also queried.

Interviews for the individual risk factor questionnaire lasted from 1-3 hours, with most being completed in 1.5-2 hours. Interviews in Oji-Cree were the most time-consuming, largely due to the fact that these almost always involved elderly volunteers, who had more years of physical activity to recall and were often inspired to relate stories during the interview session.

The questionnaires were very well received, with only a few individuals refusing to answer certain sections or questions. Some middle-aged and elderly volunteers had difficulty recalling leisure-time physical activities from childhood, and they required fairly extensive encouragement to recall physical activities in the context of other life events. There were also a number of individuals who were unaware of the diabetes status of their siblings, parents and grandparents.

A few volunteers (especially pre-teens and teens) became restless in the later stages of the interview; when this occurred, they were given a short break.

Anthropometric Measurements
Anthropometric measurements were performed during the morning of the Project House visit. Volunteers were measured without shoes in either cotton examination gowns and underclothes or in light athletic clothing. Each measurement was performed twice, and the average of the two was used in the analysis.

Height was measured to the nearest 0.1 cm using an Accustat wall-mounted stadiometer (Genentech Inc., San Francisco, California) with heels together and against the wall and buttocks, back, shoulders and head touching the wall. Weight was measured to the nearest 0.1 kg using a standard hospital balance beam scale (Health-o-Meter Inc., Bridgeview, Illinois). Body mass index (weight [kg] / height [m]2 ) was calculated as an indicator of obesity.

Waist and hip circumferences were measured using an inelastic tape over gowns or light athletic clothing. Measurements were taken to the nearest 0.5 cm at three locations: natural waist, iliac crest waist and buttocks. The natural waist was considered to be the minimal circumference between the umbilicus and xiphoid process; the iliac crest waist was measured at the top of the bony ridge of the iliac crest (determined by palpation); the buttocks were measured at the level of maximum extension.

Percent body fat and lean body mass were estimated by bioelectrical impedance analysis (BIA) using the Tanita TBF-201 Body Fat Analyzer (Tanita Corporation Inc., Tokyo, Japan). We have documented high reproducibility of percent fat estimates using this machine (intraclass correlation coefficient 0.99)13 in a sample of this population, and we have validated Tanita BIA percent fat estimates against dual energy x-ray absorptiometry (DEXA) in a group of individuals with NIDDM (unpublished data). This machine has also been validated against body composition gold standards in other populations.14

Blood Pressure
Blood pressure was measured in the right arm with the volunteer seated and the arm bared. The project co-ordinator or a qualified surveyor performed this measurement using a hand-held aneroid sphygmomanometer. Systolic pressure was recorded to the nearest 2 mmHg at the appearance of the first Korotkoff sound (phase I), and the diastolic pressure was recorded to the nearest 2 mmHg at the appearance of the fifth Korotkoff sound (phase V). The average of two measurements was used in the analysis.

Fitness Testing
A simple three-stage step test was used to estimate maximal oxygen uptake (VO2max), the most widely accepted measure of fitness level.15 Volunteers stepped on a 25.4 cm (10 inch) high exercise stepper for three minutes per stage to a maximum of three stages. Pulse rate was measured using a finger-clip pulse monitor at 2 min 30 s, 2 min 45 s and 3 min of each stage. Volunteers with medical conditions that contraindicated vigorous exercise (cardiovascular disease, respiratory disease, arthritis, amputations) were excluded. The step test was performed after two-hour blood glucose samples were drawn. This test has been validated against exercise test protocols that directly measure VO2max.15

Few problems were encountered in administering the fitness test. Most volunteers were able to step in proper rhythm, and there were no injuries or accidents related to the test.

Children under Age 10
Only anthropometric measurements were taken for children under the age of 10. Height and weight were measured as per the guidelines described above. Bioelectrical impedance analysis was performed on children 100 cm or taller, and waist-to-hip ratios on those aged 5 and older.

Discussion

Co-operation and partnership with political leaders and grass-roots organizations are essential elements of modern health research studies based in native communities. This was a stated requirement of Sandy Lake Chief and Council at the beginning of the project; their endorsement was also of crucial importance in legitimizing and promoting the project in the community.

The high rate of participation can be attributed in large part to the use of community members as recruiters and data collectors. Their knowledge of personalities and culturally appropriate visiting and recruiting techniques likely resulted in a substantially larger number of volunteers than would have other recruiting approaches (i.e. using outsiders or health professionals). Their fluency in Oji-Cree also allowed for the inclusion of older community members, many of whom do not speak English.

Local input (via the ethnographic work and the surveyors), combined with the knowledge and experience of a multidisciplinary team of medical, public health and social science researchers, resulted in the development of a set of high quality, comprehensive and culturally appropriate data collection instruments. The extensive field testing of early versions of the questionnaires also contributed substantially to this end, and it was a beneficial training exercise for the surveyors.

A number of other lessons were learned during the development and implementation of this project. For example, it appeared that the time required to complete all aspects of the protocol (2-3 hours) was excessive for some participants. While comprehensiveness is important to the validity and cost-effectiveness of public health surveys, researchers should try to keep the time required for such surveys within 2 hours.

Another lesson learned was that of flexibility in terms of location and start time. A number of teenagers and young adults did not rise until mid-morning or later, and appointment scheduling to accommodate this pattern increased participation in these groups. Additionally, certain technical aspects of the protocol (blood processing, for example) required the survey team to be based, for the most part, at the Project House. A higher level of mobility would have been desirable, in that it would have allowed for more frequent surveys in the homes of the elderly and mothers with many small children. A designated project vehicle and use of portable survey equipment would facilitate this approach (the Tanita BIA machine, for example, is small and easily transportable for measuring body composition in a mobile field survey).

The presence and activities of the SLHDP over the past several years have reinforced a pre-existing concern in the community about the emerging problem of diabetes. Many volunteers mentioned that their willingness to participate was linked to a desire to help address this health issue. Community members are now eagerly anticipating the debut of the prevention phase of the project, and key individuals and organizations have pledged their support for this endeavour. Currently, SLHDP investigators are working with the community leadership to secure funding for these activities.

Acknowledgements

This project was funded by grants from the National Institute of Health (91-DK-01) and the Ontario Ministry of Health (#04307).

References

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Author References

At the 3rd International Conference on Diabetes and Indigenous Peoples: "Theory, Reality and Hope" (May 26-30, 1995; Winnipeg, Manitoba), the Sandy Lake Health and Diabetes Project presented a series of papers and workshops. This article provides a more detailed description of the background, methodology and lessons learned in the development and implementation of this project, with special attention given to the development of a collaborative relationship between the researchers and the community.