Appendix I
Evidence Review Strategy
TABLE I-1 Evidence Review Key Questions and Study Eligibility Criteria
| Key Question (KQ) | Study Eligibility Criteria |
|---|---|
| 1. Nutritional Status of WIC Populations | |
|
1a. Are there differences in the status of nutrients of concern, dietary quality, or dietary patterns comparing WIC participants with nonparticipants? 1b. Are there differences in the status of nutrients of concern, dietary quality, or dietary patterns that are associated with the 2009 WIC food package revisions among WIC populations? 1c. Are 2009 WIC food package revisions associated with differences in food package redemption rates? 1d. Are there geographical differences in the status of nutrients of concern, dietary quality, or dietary patterns in the WIC populations? |
Populations of interest: WIC participants Exposures of interest: For KQ 1a, WIC participants versus any definition of nonparticipants For KQ 1b, any definition of pre- and post-2009 WIC food package revisions For KQ 1c, food package redemption rates (WIC benefits redeemed) For KQ 1d, different geographical area (e.g., urban versus rural) Outcomes of interest: Intake or biomarker levels of the nutrients of concern, including at least one of the following: vitamin D, vitamin C, iron, folate, potassium, calcium, and dietary fiber WIC food intake levels, and fruits and vegetables or whole grain intake levels Any dietary pattern/index Any measure of diet quality Study designs of interest: Any |
| Key Question (KQ) | Study Eligibility Criteria |
|---|---|
| 2. Health status of WIC populations | |
|
2a. What is the prevalence of health outcomes among WIC participants? 2b. Are there differences in health outcomes comparing WIC participants with nonparticipants? 2c. Are there differences in health outcomes that are associated with the 2009 WIC food package revisions among WIC populations? 2d. What is the relationship between the status of nutrients of concern, dietary quality, or dietary patterns and health outcomes in the WIC population? |
Populations of interest: WIC participants Exposures of interest: For KQ 2b, WIC participants versus any definition of nonparticipants For KQ 2c, any definition of pre- and post-2009 WIC food package revisions For KQ 2d, nutrients of concern includes at least one of the following: vitamin D, vitamin C, iron, folate, potassium, calcium, and dietary fiber; any measure of dietary pattern/index or diet quality Health outcomes of interest: Child overweight and obesity Maternal/postpartum overweight and obesity Maternal BMI Gestational weight gain Postpartum weight retention Diabetes control Growth outcomes: failure to thrive (rare), underweight, stunting Cognitive development Visual acuity Anemia Iron status Folate status Pregnancy outcomes: birth weight, preterm birth, infant mortality, neural tube defect Study designs of interest: Any (except for KQ 2a, see exclusion criteria below) Exclusion criteria for KQ 2a and 2b: Case-control study and intervention studies (any design) Not analyses of population-based datasets at the national or state level (such as NHANES, PRAMS, PNSS, or the WIC Minimum Data Set) |
| Key Question (KQ) | Study Eligibility Criteria |
|---|---|
| 3. Breastfeeding promotion and incentivizing | |
|
3a. Is participation in WIC associated with breastfeeding initiation, longer duration, and exclusivity (compared with non-WIC participants)? 3b. What are the factors associated with breastfeeding initiation, duration, and exclusivity among WIC participants? 3c. What are the associations between breastfeeding and health outcomes among WIC participants? 3d. What are the effects of breastfeeding promotion on breastfeeding initiation, duration, and exclusivity among WIC participants and among WIC-eligible or low-income populations?* 3e. Are there differences in breastfeeding initiation, duration, or exclusivity that are associated with the 2009 WIC food package revisions among WIC populations? |
Populations of interest: WIC participants For KQ 3d, WIC participants, and WIC-eligible or low-income populations Exposures of interest: For KQ 3c, exposures of interest are breastfeeding initiation, duration, or exclusivity For KQ 3e, any definition of pre- and post-2009 WIC food package revisions Outcomes of interest: Breastfeeding initiation, duration, and exclusivity Any barriers to breastfeeding For KQ 3c, outcomes of interest are described in “Health outcomes of interest” above under KQ 2 Study designs of interest: Any (except for KQ 3d, see below) For KQ 3d, include only interventional studies or programmatic studies with active intervention to promote breastfeeding |
| 4. The role of WIC food packages in preventing food insecurity | |
|
4a. Is food insecurity associated with WIC participation? 4b. What are the associations between food insecurity and health outcomes of WIC populations? 4c. Are there differences in food insecurity that are associated with the 2009 WIC food package revisions among WIC households? |
Population of interest: WIC participants Exposures of interest: For KQ 4a, WIC participants versus any definition of nonparticipants For KQ 4b, exposures of interest are any measure of food insecurity/security, and outcomes of interest are described in “Health outcomes of interest” under KQ 2 For KQ 4c, any definition of pre- and post-2009 WIC food package revisions Outcomes of interest: For KQ 4a, any measure of food insecurity/security Study designs of interest: Any |
| Key Question (KQ) | Study Eligibility Criteria |
|---|---|
| 5. Racial or ethnic differences in infant/child feeding practices and food intake patterns | |
|
5a. Among caregivers of WIC participants, nonparticipants, or low-income infants or children, are there racial or ethnic differences in their practices or beliefs regarding infant/child feeding and food intake patterns? 5b. Among WIC participants, nonparticipants, or low-income women, are there racial or ethnic differences in their personal food intake patterns, eating practices, or beliefs? |
Populations of interest: For KQ 5a, caregivers of WIC participants, nonparticipants, or low-income infants or children For KQ 5b, WIC participants, nonparticipants, or low-income women Exposures of interest: Different racial or ethnic groups Outcomes of interest: Assessment of diet quality in WIC participants or low-income women and/or children comparing race/ethnicities or focusing on one race/ethnicity Breastfeeding behaviors, perceptions, intentions, cultural factors, and experiences in WIC participants or low-income women comparing race/ethnicities or focusing on one race/ethnicity Parental feeding practices, beliefs, and behaviors comparing race/ethnicities or focusing on one race/ethnicity Diet and overweight/obesity comparing race/ethnicities or focusing on one race/ethnicity Food purchasing and preparation among different race/ethnicities or focusing on one race/ethnicity Ethnic differences in home food environment among WIC or low-income families Perceptions of eating healthy among low-income mothers and children Exclusion criteria: Not relevant to low-income mothers and children Not in the United States Not related to food and nutrition |
| Key Question (KQ) | Study Eligibility Criteria |
|---|---|
| 6. Market availability of current WIC foods | |
|
6a. What are the availability, costs, or purchase patterns of WIC foods among WIC vendors or vendors in low-income neighborhoods nationwide? 6b. What is the accessibility of WIC participants (or low-income individuals) to WIC foods? 6c. What are the determinants of store choice for WIC participants (or low-income consumers)? 6d. Were there changes in WIC food purchase patterns or availability associated with the 2009 WIC food package changes? |
Inclusion criteria: Economics of food choices and availability in low-income neighborhoods Retail food environment and healthy food availability in low-income neighborhoods Geographic, racial, ethnic, and socioeconomic disparities in the availability of food stores among low-income women Fruit and vegetable availability and selection Regional food price variations in low-income neighborhoods Exclusion criteria: Not relevant to low-income mothers and children Not in the United States Not related to food and nutrition |
| 7. Administrative feasibility and efficiency for vendors | |
|
7a. Are there differences in sales or other concerns that are associated with the 2009 WIC food package revisions among WIC-authorized vendors? |
Inclusion criteria: Qualitative interviews of WIC vendor store owners or employees Any study comparing sales between pre- and post-2009 WIC food package revisions among WIC vendors |
| 8. Barriers and incentives for WIC participants, potential participants, and their families | |
|
8a. What are the barriers and incentives to WIC program participation or acceptance of WIC food packages? |
Inclusion criteria: Any relevant data related to barriers and incentives to WIC program participation or acceptance of WIC food packages |
NOTE: KQ = key question.
* A supplemental search on MEDLINE was conducted to identify interventional studies of breastfeeding promotion or support in low-income populations for this key question.
NOTE: KQ = key question.
a Search strategy was designed for identifying all studies conducted in WIC programs or WIC populations without restriction to any outcome or study design (referred to as “WIC search” herein).
b For KQ 5 and KQ 6, a separate search strategy was developed for identifying studies conducted among low-income populations living in the United States using a combination of MeSH or search terms for Medicaid, poverty, and low income (referred to as low-income search herein). The low-income search was then combined with search terms relating to culture or race/ethnicity and diet or feeding behavior (KQ 5), as well as terms relating to food access or accessibility, food environment, food costs, store, and vendor (KQ 6).
c A supplemental search of MEDLINE was developed for identifying breastfeeding interventional studies conducted among low-income populations living in the United States using a combination of the low-income search with additional MeSH terms for Culture and Continental Population Groups and a broad search for breastfeeding, infant nutrition, and breast milk (KQ 3e).
d Sum of the total number of articles across all KQs is greater than the total number of articles included because one article can provide data relevant to more than one KQ.
TABLE I-2 MEDLINE Search Strategy to Identify Relevant Literature
| Search No. | Search Terms |
|---|---|
| WIC search | |
| 1 | “Women, Infants, and Children”.af. [af=all fields] |
| 2 | WIC.af. |
| 3 | “Special Supplemental Nutrition Program”.af. |
| 4 | 1 or 2 or 3 |
| 5 | limit 4 to (english language and yr=”2005 -Current”) |
| Supplemental low-income search for KQ 5 and KQ 6 | |
| 1 | exp Medicaid or exp Poverty [exp=search for requested subject heading and terms related to subject heading] |
| 2 | (“low income” or “low-income”).mp. [mp=search title, abstract, original title, name of substance word, subject heading word, protocol supplementary concept, rare disease supplementary concept, unique identifier] |
| 3 | 1 or 2 |
| 4 | United States.cp. [cp=country of publication] |
| 5 | 3 and 4 |
| 6 | exp Food |
| 7 | (access or accessibility).mp. |
| 8 | exp Environment or environment.mp. |
| 9 | costs.mp. or exp “Costs and Cost Analysis” |
| 10 | “purchase pattern”.tw. [tw = search title, abstract, MeSH headings, other terms, chemical names, secondary source identifier, person name as subject] |
| 11 | store.mp. |
| 12 | vendor.mp. |
| 13 | or/7-12 |
| 14 | 6 and 13 |
| 15 | 5 and 14 |
| 16 | exp Diet |
| 17 | exp Breast Feeding/or exp Bottle Feeding/or exp Feeding Behavior |
| 18 | 16 or 17 |
| 19 | exp Culture |
| 20 | exp Continental Population Groups |
| 21 | ethnicity.mp. |
| 22 | or/19-21 |
| 23 | 18 and 22 |
| Search No. | Search Terms |
|---|---|
| 24 | 5 and 23 |
| 25 | 15 or 24 |
| Supplemental breastfeeding intervention search for KQ 3e | |
| 1 | infant nutrition.mp. or exp Milk, Human/ |
| 2 | human milk.mp. |
| 3 | (human adj2 milk).tw. |
| 4 | breast milk.mp. |
| 5 | breastmilk.mp. |
| 6 | breast feeding.mp. |
| 7 | breastfeeding.mp. |
| 8 | breastfeed$.mp. |
| 9 | breast fed.mp. |
| 10 | breastfed.mp. |
| 11 | (breast adj2 fed).tw. |
| 12 | exp lactation/ |
| 13 | (lactating or lactation).mp. |
| 14 | or/1-13 |
| 15 | limit 14 to english language |
| 16 | follow-up studies/ |
| 17 | (follow-up or followup).tw. |
| 18 | exp Case-Control Studies/ |
| 19 | (case adj20 control).tw. |
| 20 | exp Longitudinal studies/ |
| 21 | longitudinal.tw. |
| 22 | exp Cohort Studies/ |
| 23 | cohort.tw. |
| 24 | (random$ or rct).tw. |
| 25 | exp randomized controlled trials/ |
| 26 | exp random allocation/ |
| 27 | exp double-blind method/ |
| 28 | exp single-blind method/ |
| 29 | randomized controlled trial.pt. |
| 30 | clinical trial.pt. |
| 31 | controlled clinical trials/ |
| Search No. | Search Terms |
|---|---|
| 32 | (clin$ adj trial$).tw. |
| 33 | ((singl$ or doubl$ or trebl$ or tripl$) adj (blind$ or mask$)).tw. (82507) |
| 34 | exp PLACEBOS/ (14540) |
| 35 | placebo$.tw. (110224) |
| 36 | exp Research Design/ (250000) |
| 37 | exp Evaluation Studies/ (203532) |
| 38 | exp Prospective Studies/ (311403) |
| 39 | exp Comparative Study/ (979477) |
| 40 | or/16-39 (3077255) |
| 41 | 15 and 40 (16311) |
| 42 | limit 41 to (addresses or bibliography or biography or case reports or congresses or consensus development conference or consensus development conference, NIH or dictionary or directory or editorial or festschrift or government publications or interview or lectures or legal cases or legislation or letter or news or newspaper article or overall or patient education handout or periodical index) |
| 43 | limit 41 to comment and (letter or editorial).pt. |
| 44 | 41 not (42 or 43) |
| 45 | limit 44 to humans |
| 46 | exp Medicaid/ or exp Poverty/ |
| 47 | (“low income” or “low-income”).mp. |
| 48 | 46 or 47 |
| 49 | United States.cp. |
| 50 | 48 and 49 |
| 51 | 45 and 50 (190) |
| 52 | limit 51 to yr=”2005 -Current” (113) |
| 53 | exp Culture/ |
| 54 | exp Continental Population Groups/ |
| 55 | ethnicity.mp. |
| 56 | or/53-55 |
| 57 | 45 and 56 (590) |
| 58 | United States.cp. (5211762) |
| 59 | 57 and 58 (337) |
| 60 | limit 59 to yr=”2005 -Current” (225) |
| 61 | 52 or 60 (310) |
