Results of linear regression analyses for mean energy content (kcal) of lunchtime fast food purchases in 2007 and 2009, before and after introduction of calorie labelling
| Model 1* | Model 2* | ||||
|---|---|---|---|---|---|
| Mean (95% CI) energy content/purchase (kcal) | P value | Mean (95% CI) energy content/purchase (kcal) | P value | ||
| Estimated marginal means | |||||
| 2007 | 829.3 (813.6 to 845.0) | — | 847.5 (837.2 to 857.8) | — | |
| 2009 | 844.6 (831.6 to 857.6) | — | 827.3 (817.8 to 836.8) | — | |
| Parameter estimates | |||||
| 2007 | Reference | — | Reference | — | |
| 2009 | 15.3 (34.5 to −3.8) | 0.12 | −20.2 (−4.5 to −35.9) | 0.01 | |
| Sex (women–men) | −111.4 (−125.6 to −97.2) | <0.001 | −52.5 (−60.0 to −45.0) | <0.001 | |
| Poverty level of store location† | −6.3 (−65.3 to 52.8) | <0.001 | 36.5 (0.3 to 72.7) | 0.05 | |
| Description of purchase: | |||||
| No of food items | — | — | 155.0 (139.6 to 170.3) | <0.001 | |
| Beverage (0=No; 1=Yes) | — | — | 33.7 (20.6 to 46.9) | <0.001 | |
| Cost (inflation adjusted) | — | — | 104.8 (98.7 to 110.9) | <0.001 | |
*Model 1 adjusted for restaurant chain, sex, and neighbourhood poverty. Model 2 further controlled for the number of food items purchased, beverage purchased, and cost. Both models included a variable for chain, to adjust for change in customer volume across the two years.
†Poverty is a continuous variable defined as the percentage of households in the store’s zip code that were below twice the national poverty level.