Table 5.
Diagnostic performance of oral fluid THC test plus Cognalyzer® test in detecting pre- and post-inhalation (PP2, N = 41)
| 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 test is positive if THC ≥ 10 ng/ml and Cognalyzer test is positive | |||||||||||
| Positive | 2 | 11 | 13 | 50.0 (6.7–93.2) | 85.9 (76.2–92.7) | 84.1 (74.4–91.3) | 14.1 (7.3–23.8) | 50.0 (6.8–93.2) | 15.4% (1.9–45.4) | 97.1% (89.9–99.6) | 0.013 |
| Negative | 2 | 67 | 69 | – | – | – | – | – | – | ||
| Total | 4 | 78 | 82 | – | – | – | – | – | – | ||
| Oral fluid test is positive if THC ≥ 25 ng/ml and Cognalyzer test is positive | |||||||||||
| Positive | 0 | 6 | 6 | 0.0 (0.0–60.2) | 92.3 (84.0–97.1) | 87.8 (78.7–94.0) | 7.7 (2.9–16.0) | 100.0 (39.8–100.0) | 0.0% (0.0–45.9) | 94.7% (78.1–98.5) | 0.527 |
| Negative | 4 | 72 | 76 | – | – | – | – | – | – | ||
| Total | 4 | 78 | 82 | – | – | – | – | – | – | ||
McNemar’s chi-squared test was used to compare the difference in performance between the diagnostic test being evaluated and the comparison standard