Table 3.
Diagnostic performance of oral fluid THC concentration in the full study population (n = 74)
| Comparison standard vs. oral fluid THC test—ITT population (positive = saliva THC > 0.5 ng/ml) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 4-h post-inhalation | Pre-inhalation | Total | Sensitivity (95% CI) | Specificity (95% CI) | Accuracy (95% CI) | Percent false positive (95% CI) | Percent false negative (95% CI) | PPV (95% CI) | NPV (95% CI) | p value | |
| Oral fluid THC positive | 48 | 25 | 73 | 100 (92.6–100) | 66.2 (54.3–76.8) | 79.5 (71.3–86.3) | 33.8 (23.2–45.7) | 0 (0–7.4) | 65.7% (53.7–76.5) | 100.0% (92.7–100.0) | < 0.001 |
| Oral fluid THC negative | 0 | 49 | 49 | – | – | – | – | – | – | ||
| Total | 48 | 74 | 122 | – | – | – | – | – | – | ||
McNemar’s chi-squared test was used to compare the difference in performance between the diagnostic test being evaluated and the comparison standard