Table 3 Prevalence of different types of bullying with confidence interval (95%), among the 402 students enrolled in the pre and post intervention, according to the neighborhood socio-economic index (SEI) of the nine institutions

Method

School SEI

Pre

n

(%; CI 95%)

Post

n

(%; CI 95%)

p-value

Pre

n

(%; CI 95%)

Post

n

(%;CI 95%)

p-value

Pre

n

(%;CI 95%)

Post

n

(%;CI 95%)

p-value

Sentinel question

A

3

(1.8; -0.2 – 3.8)

3

(1.8; -3.2 – 6.8)

0.98

19

(11.1; 6.3-15.9)

21

(12.6; 7.6-17.6)

0.68

15

(8.8; 4.5-13.1 )

24

(14.4; 9.1-19.7)

0.11

B

8

(4.4; 1.5-7.3)

2

(1.1; -0.4-2.6)

<0.05

26

(14.3; 9.4-19.2)

15

(7.9; 4.1-11.7)

<0.05

16

(8.8; 4.8-12.8)

7

(3.7; 1-6.4)

<0.05

C

2

(3.9; -7.8-15.6)

1

(2.2; -2.2-6.6)

0.63

10

(19.6; 7.9-31.3)

8

(17.8; 6.5-29.5)

0.82

10

(19.6; 7.9-31.3)

5

(11.1; 1.8 - 20.4)

0.25

Five-question

A

33

(19.5; 13.5-25.5)

39

(23.4; 17-29.8)

0.39

55

(32.5; 25.4 - 39.6)

60

(35.9; 28.6-43.2)

0.51

41

(24.3;17.8-30.8)

53

(31.7;24.7-38.7)

0.13

B

54

(29.7; 22.9-36.2)

33

(17.4; 12-22.8)

<0.01

67

(36.8; 29.9-43.7)

49

(25.8; 19.6-32)

<0.05

52

(28.6; 22.2-35)

44

(23.2; 17.2-29.2)

0.23

C

16

(31.4; 16.7-46.1)

14

(29.5; 15.8-43.2)

0.86

28

(54.9; 40.2-69.6)

19

(42.2; 27.6-56.8)

0.22

25

(49; 34.2-63.8 )

16

(35.6; 21.5-49.7)

0.18

Score of seven

A

45

(26.6; 19.9-33.3)

54

(32.3; 25.2-39.4)

0.25

85

(50.3; 42.7-57.9)

94

(56.3; 48.8-63.8)

0.27

58

(34.3;27.1-41.5)

69

(41.3; 33.8-48.8)

0.18

B

74

(40.7; 33.7-47.7)

46

(24.2; 18.1-30.3)

<0.001

104

(57.1; 50-64.2)

82

(43.2; 36.1-50.3 )

<0.01

86

(47.3; 40.2-54.4)

63

(33.2; 26.5-39.9)

<0.01

C

22

(43.1; 30.6-55.6)

18

(40; 25.5-54.5)

0.76

39

(76.5; 64-89)

28

(62.2; 47.9-76.5)

0.13

30

(58.8; 44.3-73.3)

24

(53.3; 38.6-68)

0.59

Method

School SEI

Pre

n

(%; CI 95%)

Post

n

(%; CI 95%)

p-value

Pre

n

(%; CI 95%)

Post

n

(%;CI 95%)

p-value

Pre

n

(%;CI 95%)

Post

n

(%;CI 95%)

p-value

Sentinel question

A

12

(7.1; 3.2-10.3)

7

(4.2; 1.2-7.2)

0.25

16

(9.5; 5.1-13.9)

11

(6.6; 2.9-10.3)

0.33

46

(27.2; 20.4-34)

51

(30.5; 23.5-37)

0.50

B

24

(13.2; 8.4-18)

5

(2.6; 0.3-4.9)

<0.05

28

(15.4; 10.3-20.5)

12

(6.3;2.8-9.8)

<0.01

58

(31.2; 24.6-37.8)

65

(34.2; 27.4-41)

0.63

C

10

(19.6; 8.9-30.3)

5

(11.1; 3.7-18.5)

0.26

10

(19.6; 7.9-31.3)

7

(15.6; 4.9-26.3)

0.61

16

(31.4; 17.7-45.1)

18

(40;25.5-54.5)

0.38

Five-question

A

128

(75.7; 69.2-82.2)

128

(76.7; 70.3-83.1)

0.85

31

(18.3; 12.4-24.2)

26

(15.6; 10.1-21.1

0.50

75

(44.4;36.8-52)

75

(44.9; 37.4-52.4)

0.92

B

139

(76.4; 71.8-81)

124

(65.3; 59.2-71.4)

<0.05

54

(29.7; 23.2-36.2)

38

(20;14.3-25.7

<0.05

90

(49.5;42.1-56.6)

80

(42.1; 35.1-49.1)

0.16

C

46

(90.2; 81.4-99)

33

(73.3; 60.2-86.4)

0.06

21

(41.2; 26.7-55.7)

18

(40; 25.5-54.5)

0.90

27

(52.9; 38.2-67.6)

23

(51.1; 36.3-65.9)

0.86

Score of seven

A

142

(84; 78.4-89.6)

143

(85.6; 80.3-90.9)

0.68

48

(28.4;21.6-35.2)

46

(27.5;20.8-34.2)

0.86

94

(55.6;48.1-63.1)

89

(53.3;45.7-60.9)

0.67

B

157

(86.3;81.4-91.2)

144

(75.8;69.7-81.9)

< 0.01

88

(48.4;41.3-55.5)

58

(30.5;23.9-37.1)

<0.001

116

(63.7;56.8-70.6)

106

(55.8;48.7-62.9)

0.12

C

48

(94.1;87.2-87.2)

38

(84.4;73.7-95.1)

0.12

27

(52.9;38.2-67.6)

20

(44.4;29.7-59.1)

0.41

36

(70.6;57.2-84)

28

(62.2;47.9-76.5)

0.39