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Table 3 Self-reported amphetamine-type stimulant use compared with urine toxicology results by age, HIV status, and sex-work venue

From: Testing for amphetamine-type stimulant (ATS) use to ascertain validity of self-reported ATS use among young female sex workers in Cambodia

Self-reported ATS use compared to urine toxicology results by age group

Age 16-18 years

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

2

1

 

No

0

8

   

95% CI

Sensitivity (%)

100

 

−−

Specificity (%)

88.9

 

68.4–100

Positive predictive value (%)

66.7

 

13.3–100

Negative predictive value (%)

100

 

−−

Age 19-24 years

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

5

3

 

No

2

52

   

95% CI

Sensitivity (%)

71.4

 

38.3–100

Specificity (%)

94.6

 

88.5–100

Positive predictive value (%)

62.5

 

29.0–96.0

Negative predictive value (%)

96.3

 

91.3–100

Age 25-29 years

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

18

2

 

No

1

106

   

95% CI

Sensitivity (%)

94.7

 

84.7–100

Specificity (%)

98.2

 

95.6–100

Positive predictive value (%)

90.0

 

76.9–100

Negative predictive value (%)

99.1

 

97.2–100

Self-reported ATS use compared to urine toxicology results by HIV status

HIV positive

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

9

2

 

No

1

21

   

95% CI

Sensitivity (%)

90.0

 

71.4–100

Specificity (%)

91.3

 

79.8–100

Positive predictive value (%)

81.8

 

59.0–100

Negative predictive value (%)

95.5

 

86.8–100

HIV negative

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

16

4

 

No

2

145

   

95% CI

Sensitivity (%)

88.9

 

74.4–100

Specificity (%)

97.3

 

94.7–99.9

Positive predictive value (%)

80.0

 

62.5–97.5

Negative predictive value (%)

98.6

 

96.8–100

Self-reported ATS use compared to urine toxicology results by type of sex work setting

Entertainment and/or service

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

3

3

 

No

2

131

   

95% CI

Sensitivity (%)

60.0

 

17.1–100

Specificity (%)

97.8

 

95.3–100

Positive predictive value (%)

50.0

 

10.0–90.0

Negative predictive value (%)

98.5

 

96.4–100

Freelance and/or brothel

Urine toxicology results (n)

  

Positive

Negative

Self-reported use (n)

Yes

22

3

 

No

1

35

   

95% CI

Sensitivity (%)

95.7

 

87.3–100

Specificity (%)

92.1

 

82.5–100

Positive predictive value (%)

88.0

 

75.2–100

Negative predictive value (%)

97.2

 

91.9–100