Table 2.
Concordance, Cohen’s kappa, Sensitivity, Specificity, Positive Predictive Value and Negative Predictive Value of TLFB Assuming Hair Analysis as Gold Standards
| Head and Body Hair Combined | 3-Month Visit | 6-Month Visit | 12-Month Visit |
|---|---|---|---|
| Cannabis | |||
| N | 766 | 743 | 697 |
| Concordance % (Kappa) | 77.81 (.51) | 79.14 (.54) | 75.32 (.49) |
| Under-Reporting % (Over-Reporting %) | 18.18 (30.00) | 17.25 (27.73) | 22.01 (28.67) |
| Sensitivity % (Specificity %) | 81.82 (70.00) | 82.75 (72.27) | 77.99 (71.33) |
| Positive Predictive Value % (Negative Predictive Value %) | 84.15 (66.42) | 85.02 (68.77) | 80.30 (68.38) |
| Cocaine | |||
| N | 756 | 726 | 665 |
| Concordance % (Kappa) | 65.21 (.35) | 65.01 (.35) | 61.20 (.31) |
| Under-Reporting % (Over-Reporting %) | 45.30 (9.82) | 45.44 (7.50) | 52.12 (6.22) |
| Sensitivity % (Specificity %) | 54.70 (90.18) | 54.56 (92.50) | 47.88 (93.78) |
| Positive Predictive Value % (Negative Predictive Value %) | 92.97 (45.60) | 95.03 (43.63) | 94.96 (42.39) |
| Prescribed Opioids | |||
| N | 706 | 655 | 591 |
| Concordance % (Kappa) | 64.87 (.18) | 70.99 (.30) | 71.40 (.27) |
| Under-Reporting % (Over-Reporting %) | 72.73 (11.14) | 65.00 (8.19) | 67.00 (8.95) |
| Sensitivity % (Specificity %) | 27.27 (88.86) | 35.00 (91.81) | 33.00 (91.05) |
| Positive Predictive Value % (Negative Predictive Value %) | 60.98 (65.69) | 71.19 (70.95) | 65.35 (72.65) |
| Street Opioids | |||
| N | 706 | 655 | 591 |
| Concordance % (Kappa) | 90.51 (.73) | 92.98 (.81) | 91.03 (.73) |
| Under-Reporting % (Over-Reporting %) | 21.69 (5.74) | 17.16 (3.50) | 25.37 (4.16) |
| Sensitivity % (Specificity %) | 78.31 (94.26) | 82.84 (96.50) | 74.63 (95.84) |
| Positive Predictive Value % (Negative Predictive Value %) | 80.75 (93.39) | 89.17 (94.18) | 84.03 (92.80) |