Table 1 Sosiodemographic and sexual behaviour characteristics - prevalence and crude odds ratios for clinic based testing

Total

607

338

(55.7)

NA

505

106

(21.0)

NA

Age

 15-16

179

81

(45.3)

1.00

< 0.001

149

19

(12.8)

1.00

0.001

< 0.001

0.80

 17

193

105

(54.4)

1.44

0.96–2.17

196

40

(20.4)

1.75

0.97–3.18

 18

177

104

(58.8)

1.72

1.13–2.62

114

28

(24.6)

2.23

1.17–4.24

,

 19-20

58

48

(82.8)

5.81

2.77–12.20

46

19

(41.3)

4.81

2.25–10.29

Family and culture

Ethnicity

,

 Norwegian

433

232

(53.6)

1.00

0.049

353

56

(15.9)

1.00

< 0.001

0.001

0.022

 Sami/Sami-Norwegian

131

85

(64.9)

1.60

1.07–2.40

115

37

(32.2)

2.52

1.55–4.08

 Other

43

21

(48.8)

0.83

0.44–1.55

36

13

(36.1)

3.00

1.43–6.27

Residence in school year

 At home

380

196

(51.6)

1.00

0.007

314

55

(17.5)

1.00

0.015

0.001

0.78

 Other³

226

142

(62.8)

1.59

1.13–2.22

191

51

(26.7)

1.72

1.11–2.65

Mothers education

 ≤ High school/don’t know

338

184

(54.4)

1.00

0.46

334

62

(18.6)

1.00

0.074

0.005

0.32

 ≥ College

268

154

(57.5)

1.13

0.82–1.56

169

43

(25.4)

1.50

0.96–2.33

High school

Study affiliation

 Academic

323

189

(52.1)

1.00

0.029

181

45

(24.9)

1.00

0.11

0.040

0.010

 Vocational

244

149

(61.1)

1.44

1.04–2.01

324

61

(18.8)

0.70

0.45–1.09

Alcohol/drug use

 Low

144

57

(40.4)

1.00

< 0.001

140

21

(15.3)

1.00

0.003

< 0.001

0.49

 Medium

343

193

(56.3)

1.90

1.27–2.82

212

40

(18.9)

1.29

0.72–2.29

 High

118

86

(72.9)

3.96

2.34–6.71

144

45

(31.3)

2.51

1.40–4.50

Sexual behaviour

Age at first intercourse

 ≥ 15 years

352

167

(47.4)

1.00

< 0.001

311

40

(12.9)

1.00

< 0.001

< 0.001

0.15

 ≤ 14 years

252

171

(67.9)

2.34

1.67–3.28

172

59

(34.3)

3.54

2.24–5.59

Years sexually active

 ≤ 1 year

162

54

(33.3)

1.00

< 0.001

171

13

(7.6)

1.00

< 0.001

< 0.001

0.50

 ≥ 2 years

442

284

(64.3)

3.60

2.46–5.26

312

86

(27.6)

4.63

2.50–8.58

Condom use first intercourse

 Yes

358

198

(55.3)

1.00

0.78

267

40

(15.0)

1.00

0.001

0.15

0.014

 No⁴

248

140

(56.5)

1.05

0.76–1.45

226

61

(27.0)

2.10

1.34–3.28

Currently in relationship

 Yes

322

185

(57.5)

1.00

0.35

179

42

(23.5)

1.00

0.31

0.001

0.79

 No

285

153

(53.7)

0.86

0.62–1.18

326

64

(19.6)

0.80

0.51–1.24

Sex partners past 6 months

 0-1

352

181

(51.4)

1.00

0.010

273

35

(12.8)

1.00

< 0.001

< 0.001

0.013

 ≥ 2

248

154

(62.1)

1.55

1.11–2.16

194

62

(32.0)

3.19

2.01–5.09

Life time no of sex partners

 1-2

206

64

(31.1)

1.00

< 0.001

218

11

(5.0)

1.00

< 0.001

< 0.001

0.17

 3-5

191

107

(56.0)

2.83

1.87–4.26

123

31

(25.2)

6.34

3.06–13.16

 ≥ 6

201

163

(81.1)

9.52

6.01–15.08

119

53

(44.5)

15.11

7.46–30.62

Last sexual partner

Age difference

 Same age or younger

144

66

(45.8)

1.00

0.005

413

80

(19.4)

1.00

0.042

< 0.001

0.78

 Older (≥ 1 year)

445

264

(59.3)

1.72

1.18–2.52

54

17

(31.5)

1.91

1.03–3.57

Condom use last intercourse

 Yes

94

33

(35.1)

1.00

< 0.001

319

76

(23.8)

1.00

0.009

< 0.001

0.36

 No⁵

513

305

(59.5)

2.71

1.71–4.29

168

23

(13.7)

1.97

1.18–3.28

School based testing

Provision of urine sample

 Yes

564

313

(55.5)

1.00

0.74

470

97

(20.6)

1.00

0.48

0.49

0.73

 No

43

25

(58.1)

1.11

0.59–2.09

35

9

(25.7)

1.33

0.60–2.93

Chlamydia test result

 Negative

523

290

(55.4)

1.00

0.94

448

91

(20.3)

1.00

0.14

0.11

0.23

 Positive

41

23

(56.1)

1.03

0.54–1.95

17

6

(35.3)

2.14

0.77–5.94