Family Consumer Behaviors, Adolescent Prediabetes and Diabetes in the National Health and Nutrition Examination Survey (2007-2010)

NHANES is a nationwide cross-sectional survey conducted by the Centers for Disease Control and Prevention (CDC), a detailed description of which is available elsewhere. The NHANES administers annual face-to-face health surveys in a nationally representative sample of civilian, non-institutionalized households in the US. In addition to core questions documenting household demographic and health characteristics, survey instruments collect information on current health and disease status, including several questionnaires on health quality indicators and lifestyle practices. Besides survey instruments, NHANES collects information on select clinical examinations and laboratory tests.

The study will include NHANES subjects from 2007-2010 who were 12-19 years old and from households where an eligible person had administered the consumer behavior questionnaire (CBQ). The CBQ was developed in partnership with the Economic Research Service of the US Department of Agriculture and has been a part of NHANES from 2007-2010. A total of 2,520 children and adolescents met the eligibility criteria for the study.

Food Availability and Expenditure The primary variables of interest for the study included household healthy food availability and supermarket spending on food that was assessed in the CBQ. Availability will be examined for five food items in the household including fruits, dark green vegetables, fat-free/low fat milk, salty snacks, and soft drinks. The responses for each item were ordinal, ranging from always, most of the time, sometimes, rarely, to never. Dark green vegetables included fresh dried, canned and frozen vegetables, and interviewers were instructed to exclude lettuce. Salty snacks included chips and crackers, but not nuts. The types of milk considered low-fat were skim or 0% and 1%. Soft drinks included soda, fruit-flavored drink and fruit punch; while 100% juice or sports drinks were excluded.

A composite variable that incorporated answers to all the five food items will be created for food availability. First, a decreasing score ranging from 5 to 1 was assigned from "always" to "never" responses for the healthy food items including fruits, dark green vegetables, and fat-free/low fat milk; whereas an increasing score ranging from 1 to 5 was assigned for "always" to "never" response for unhealthy food items including salty snacks and soft drinks. A cumulative score will be calculated for each participant that ranged from 5 to 25, where a higher value indicated higher availability of healthy food(s) in the household. A cumulative score will only be calculated for participants with a non-missing response on all five questions.

Food spending will be examined by the amount of money (in US Dollars) the household spent in the past 30 days on supermarket store purchases, non-food items, food at other stores, eating out and carryout/delivered foods. Non-food spending was asked as a part of supermarket store spending and it included money used towards cleaning and paper supplies, pet food, alcoholic beverages and cigarettes. This will be first subtracted from the total supermarket spending to give supermarket spending on food items alone. It will then be divided by the total food spending of the household (sum of the above food spending questions) to also calculate the proportion of spending on supermarket store food items.