The Impact of WIC on Dietary Intake and dnutritional titi lstatust Nancy Cole IOM Workshop on Planning a WIC Research Agenda July 20, 2010
WIC Impacts WIC foods for women & children Milk (and/or cheese or soy products) Eggs Beans/peanut butter Canned fish (women only) Juice Breakfast cereals Fruits and vegetables Whole grains Healthy food choices Improved dietary intake Improved nutritional status 2
Impact Measures WIC foods for women & children Milk (and/or cheese or soy products) Eggs Beans/peanut butter Canned fish (women only) Juice Breakfast cereals Fruits and vegetables Whole grains Healthy food choices 1. Voucher redemption 2. Consumption of WIC foods (NHANES) Improved dietary intake 3. Dietary recalls (NHANES) Improved nutritional status 4. Anemia, body weight (WIC certification data) 3
Challenge for Evaluating WIC Impacts Identify a comparison group for measuring outcomes relative to what would be observed in the absence of WIC Previous research : NHANES but can t measure impacts; pacs;samples pesof women ae are too oosmall; no osae State identifiers Alternatives ti to finding a true comparison group 1. Dose-response based on voucher redemption 2. Cross-State comparisons that control for variations in WIC-approved foods 4
Voucher Pick-up and Redemption Voucher pick-up is a measure of participation Overall rate is about 90% a WIC Cost Containment Study b found Voucher pick-up declined ed from 100% in 1 st month to 73 to 84 percent across 6 States by month 6 Redemption of picked-up vouchers varied by: State: from 81 to 91% across 6 States Participant category: women had lowest redemption rates, and children highest h in all 6 States a Based on administrative counts of participants p compared with WIC-PC counts of enrollees. b Kirlin, John, Nancy Cole, and Chris Logan. Assessment of WIC Cost-Containment Practices Final Report. USDA, Economic Research Service. E-FAN-03-005. February 2003. 5
Voucher Redemption: Potential Research 1. Examine the impact of revised WIC food packages on redemption Pre-post comparison Across States grouped by policy options 2.Examine the impact of revised WIC food packages on declines in redemption during the certification period If there is less decline, is it attributable to New foods (F&V, whole grains)? Lower prescribed quantities (milk/cheese/juice/eggs)? 3. Control for variation in voucher redemption rates in dose-response models of dietary intake 6
Consumption of WIC Foods Are WIC foods consumed by WIC participants? (Regardless of whether they would have consumed these foods in the absence of WIC.) Prior research: NHANES dietary recalls c Except for milk, on any given day, WIC-approved foods in each category were consumed by no more than 30% of WIC children (although 68% of children consumed any cereal) WIC children were significantly more likely to consume WIC cereals than other low-income children c Cole, Nancy and Mary Kay Fox. Diet Quality of American Young Children by WIC Participation Status: Data from the National Health and Nutrition Examination Survey, 1999-2004. 7
Consumption of WIC Foods: Potential Research Marginal impact on WIC participants consumption of WIC foods What percentage of the food package is consumed by the participant? What percentage is consumed by other family members? How does the consumption rate vary by food category: New foods (F&V, whole grains) Food categories with increased substitution (milk, canned fish) Food categories with decreased quantities (milk, cheese, juice) 8
WIC Impacts on Dietary Intake Prior research: Descriptive comparisons of WIC participant children and low-income nonparticipants using NHANES Results Virtually all children age 1-4 had adequate usual daily intakes of all vitamins and minerals with defined EARs (except vitamin E). WIC children had slightly lower HEI scores than higher- income nonparticipants 9
Dietary Intake: Potential Research Impact of revised WIC food packages on dietary intake Replicate NHANES analysis in period after implementation of revised food packages Use CDC Research Data Center to control for characteristics of State WIC food lists (amount of choice within each food category) Children in restrictive states provide a valid control group for lower bound estimates of the impact of WIC (samples in restrictive States may not be large enough) 10
WIC Impacts on Nutritional/Health Status Prior research: Dose-response approach to estimate WIC impacts was used in WIC Cost Containment Study Voucher redemption measures the dose Outcome measures = change in status over the 6-month WIC certification period (observed only for recertifications) Statistically significant postive impacts of WIC for for children on: Change in height-for-age Probability of exiting underweight Probability of exiting anemia (only when voucher redemption is measured by ypercent of cereal ounces on redeemed vouchers) 11
Nutrition Status: Potential Research Descriptive analysis of change in nutritional/health status a) For a sample of States, obtain a second WIC-PC extract 6 months after the WIC-PC submission and examine changes in status b) Same as (a), but also obtain measures of voucher redemption for dose-response analysis 12
Summary: Potential Research Voucher redemption Trends before and after revised food packages Consumption of WIC foods Analysis of NHANES, and comparison to pre-implementation of revised food packages. Possibly control for characteristics of States food lists. New survey to understand marginal impact of WIC on consumption of WIC foods and reasons for not consuming full prescription. p Dietary Intakes NHANES analysis of WIC participants p and nonparticipants, p and compare to pre-implementation of revised food packages Nutritional/health status Analysis of administrative data from a sample of states 13