Table 2. Regression-Based Difference-in-Differences Estimates of Mean Healthy Eating Index-2010 (HEI-2010) Scores Among National School Lunch Program (NSLP) Participants and Nonparticipants From Before to After the Healthy, Hunger-Free Kids Act (HHFKA)a.
| HEI-2010 score | Mean (95% CI) | Difference-in-differences estimate (95% CI)e | |||||
|---|---|---|---|---|---|---|---|
| NSLP participants | NSLP nonparticipants | ||||||
| Before HHFKA implementationc | After HHFKA implementation | Differenced | Before HHFKA implementationc | After HHFKA implementation | Differenced | ||
| Low incomeb | |||||||
| Lunch | 42.7 (40.9 to 44.5) | 54.6 (53.0 to 56.1) | 11.9 (9.4 to 14.3) | 34.8 (32.7 to 36.9) | 34.1 (32.1 to 36.0) | −0.7 (−3.6 to 2.1) | 12.6 (8.9 to 16.3) |
| Total day | 47.2 (45.5 to 48.9) | 51.3 (49.8 to 52.8) | 4.2 (2.0 to 6.4) | 44.7 (43.4 to 46.1) | 45.5 (43.8 to 47.2) | 0.8 (−1.3 to 2.9) | 3.4 (0.5 to 6.3) |
| Low-middle incomeb | |||||||
| Lunch | 40.4 (37.2 to 43.7) | 54.8 (51.1 to 58.4) | 14.3 (9.6 to 19.1) | 34.2 (30.1 to 38.2) | 36.1 (32.7 to 39.5) | 2.0 (−2.9 to 6.8) | 12.4 (4.9 to 19.9) |
| Total day | 45.9 (43.7 to 48.2) | 51.4 (48.5 to 54.3) | 5.4 (2.2 to 8.6) | 45.2 (42.7 to 47.7) | 45.9 (43.7 to 48.0) | 0.7 (−2.6 to 4.0) | 4.7 (0.8 to 8.7) |
| Middle-high incomeb | |||||||
| Lunch | 42.7 (40.6 to 44.9) | 55.5 (53.2 to 57.9) | 12.8 (9.8 to 15.8) | 38.9 (37.4 to 40.4) | 43.6 (41.7 to 45.5) | 4.7 (2.3 to 7.0) | 8.1 (4.2 to 12.0) |
| Total day | 46.7 (45.6 to 47.7) | 51.9 (50.0 to 53.9) | 5.3 (3.2 to 7.4) | 46.7 (45.7 to 47.7) | 50.1 (48.5 to 51.7) | 3.4 (1.6 to 5.3) | 1.9 (−0.8 to 4.5) |
The HHFKA of 2010 was a policy implemented nationwide in July 2012 that required changes to the school nutrition standards for meals served as part of the NSLP to more closely align with the 2010 Dietary Guidelines for Americans. This was the first policy change to school nutrition standards since 1994. The pre-HHFKA period includes data from 2007-2010 and post-HHFKA period includes data from 2013-2016.
Income was categorized using criteria for free, reduced-price and full-price lunch (≤130% of the federal poverty line indicates low income; >130%-≤185% of the federal poverty line, low-middle income; and >185% of the federal poverty line, middle-high income).
95% CIs are estimated accounting for survey sampling design from Taylor series linearized standard errors.
Mean difference is calculated as post-HHFKA mean score minus pre-HHFKA mean score.
Regression-based difference-in-differences estimates were adjusted for age, sex, race/ethnicity, school level, period of dietary recall, and body mass index.