Page 82 - ON THE WAY TO HEALTHIER SCHOOL CANTEENS - Irma Evenhuis
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Chapter 5. Effect evaluation
The effect of a healthier canteen (independent variable) on student purchase behaviour (dependent variable) was also assessed using mixed logistic regression analyses with a random intercept for schools for boys and girls separately. We used the health level of the canteen at follow-up for each of the three subtopics of a healthier canteen. Due to non- linearity with student purchase behaviour, again a dichotomous variable was created, based on the guidelines, which state that 60% or higher is a healthier availability and accessibility, respectively. Again, the model was extended with demographic variables (model 2) and students’ behavioural (model 3) and environmental determinants (model 4). Statistical analyses were performed using the IBM SPSS Statistics version 24.0 (IBM corporation (IBM Nederland), Amsterdam, The Netherlands. Odds ratios and 95% confidence intervals (CI’s) are presented.
RESULTS
Baseline characteristics
We included data from 645 students of the intervention schools and 731 students of the control schools in the analyses (Table 5.1). Both groups consisted of more girls than boys (56% and 53%, respectively). The included schools offered education at the vocational (n = 6) level, the senior general/pre-university level (n = 5), or a combination of both levels (n = 9). The level of education was broadly similar for intervention and control schools. However, in intervention schools slightly more girls followed the vocational education level (46.6%) compared to boys (41.4%), while the opposite was the case in control schools (girls, 39.5%; boys 46.2%). Most students indicated that they did bring food and drinks from home to school four or more times a week (for food, intervention schools (IS) 91.8 and control schools (CS) 89.2%; for drinks, IS 90.4% and CS 88.5%). The majority of students reported that they bought foods or drinks in the school cafeteria (IS 55.5%; CS 64.4%) or vending machine (IS 63.6%; CS 61.1%) less than once per week. During school time, 62.2% and 67.6% of the students in the IS reported buying food or drinks outside school less than once a week, compared to 65.6% and 73.6% in the CS.
Table 5.1. Baseline characteristics of students divided by intervention or control school and gender.
   Number of students – n (%)
DEMOGRAPHIC VARIABLES
Total
645 (46.9)
Boys
302 (46.8)
Girls
343 (53.2)
13.42 (0.68)
159 (46.4) 62 (18.1) 122 (35.6)
2.88 (0.84) 2.44 (0.63)
Total
731 (53.1)
13.35 (0.62)
310 (42.4) 190 (26.0) 231 (31.6)
2.91 (0.86) 2.39 (0.68)
Boys
318 (43.5)
13.38 (0.66)
147 (46.2) 78 (24.5) 93 (29.2)
2.67 (0.88) 2.31 (0.71)
Girls
413 (56.5)
13.33 (0.59)
163 (39.5) 112 (27.1) 138 (33.4)
3.09 (0.80) 2.46 (0.66)
Age (years)- Mean (SD)
School Level n (%)
Vocational education
Senior general education
Pre-university education
BEHAVIOURAL DETERMINANTS - Mean (SD)a
Attitude 2.81 (0.84) 2.73 (0.84) Subjective norm 2.39 (0.64) 2.32 (0.64)
Intervention schools (N=10)
Control schools (N=10)
 13.39 (0.62)
13.35 (0.55)
125 (41.4) 86 (28.5) 91 (30.1)
284 (44.0) 148 (22.9) 213 (33.0)
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