Table 2 Distribution of demographic and socio-economic characteristics of cases and controls

No:

%

No:

%

Sex

 Male

371

82.4

246

54.7

 Female

79

17.6

204

45.3

Age

 10–13

299

66.4

233

51.8

 14–15

78

17.4

88

19.6

 16–19

73

16.2

129

28.6

Ethnicity

 Sinhalese

330

73.3

398

88.4

 Muslim

80

17.8

30

6.7

 Tamil

39

8.7

20

4.5

 Burger

1

0.2

2

0.4

Religion

 Buddhist

286

63.5

375

83.3

 Catholic/ Christianity

64

14.2

45

10

 Hindu

21

4.7

12

2.7

 Islam

79

17.6

18

4

Monthly income

 Rs 10,000 -15,000

32

7.1

92

20.4

 Rs 15,001- Rs 30,000

127

28.2

163

36.2

 Rs 30,001- Rs 45,000

151

33.6

114

25.3

 Rs 45,001- Rs 60,000

83

18.4

42

9.3

  > Rs 60,000

53

11.8

28

6.2

 Not known

4

0.9

11

2.4

Social class^a

 Class I

38

8.2

17

3.8

 Class II

44

9.5

19

4.2

 Class III

202

43.5

98

21.8

 Class IV

130

28.0

241

53.6

 Class V

36

10.8

75

16.6

Standard of Living^b

 High

139

30.0

110

24.4

 Medium

280

60.3

247

54.9

 Low

31

6.7

93

20.7