Table 2.
Differences in intervention and control groups over time for primary and secondary outcomesa.
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Intervention | Control | Intervention versus controla | ||||||||||
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Baseline (n=656), mean (SD) | 15-Month follow-up (n=334), mean (SD) | Baseline (n=675), mean (SD) | 15-Month follow-up (n=397), mean (SD) | Main analysis (15-month versus baseline) | ||||||||
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Group by time differential effect (95% CI) | P value | |||||||
| Primary outcomes | |||||||||||||
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Percentage per student of lunch items that are “everyday” | 44.3 (34.3) | 51.0 (34.0) | 43.2 (36.3) | 39.4 (36.0) | 11.5 (7.3 to 15.6) | <.001b | ||||||
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Percentage per student of lunch items that are “occasional” | 30.7 (30.8) | 30.4 (29.7) | 40.9 (35.7) | 45.7 (37.7) | –5.4 (–9.4 to –1.5) | .007b | ||||||
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Percentage per student of lunch items that are “should not be sold” | 25.0 (30.9) | 18.6 (28.3) | 16.0 (24.7) | 15.0 (23.2) | –6.0 (–9.1 to –2.9) | <.001b | ||||||
| Secondary outcomes | |||||||||||||
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Energy (kJ) per student lunch order | 2172.5 (976.9) | 2211.7 (922.3) | 1992.8 (793.1) | 1943.4 (796.6) | 48.8 (–34.6 to 132.2) | .25 | ||||||
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Saturated fat (g) per student lunch order | 7.3 (5.7) | 7.0 (5.0) | 5.7 (4.4) | 5.5 (4.4) | –0.0 (–0.5 to 0.5) | .99 | ||||||
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Sugar (g) per student lunch order | 22.4 (22.8) | 22.5 (21.0) | 15.3 (16.2) | 12.8 (15.0) | 1.7 (–0.1 to 3.5) | .07 | ||||||
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Sodium (mg) per student lunch order | 778.9 (354.1) | 795.9 (368.8) | 808.3 (398.2) | 789.3 (384.1) | 0.35 (–36.2 to 36.9) | .99 | ||||||
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Weekly revenue (Aus $)c per school | 896.1 (449.9) | 1243.8 (485.9) | 769.6 (372.8) | 1798.5 (653.9) | –673.4 (–1252.6 to –94.2) | .03b | ||||||
aAll models included a random intercept for school, a nested random intercept and random time effect for students, and fixed effects for the school sector and Socio-Economic Indexes for Australia. All available data were incorporated into the model (baseline, 2-months, and 15-months) to describe purchasing patterns over time.
bP<.05.
cAll $ amounts are in Aus $. A currency exchange rate of Aus $1 = US $0.65 was applicable as of February 2024.