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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