Table 3.
Impact of KMSK cutoff score on sensitivity and specificity
| Substance | Cutoff (≥) | Sensitivity (%) | Specificity (%) | Sensitivity + specificity | χ2 value | p value | PPP | NPP |
|---|---|---|---|---|---|---|---|---|
| Alcohol | 7 | 100.0 | 50.7 | 150.7 | 110.5 | <.0001 | .500 | 1.000 |
| 8 | 98.6 | 58.2 | 156.8 | 130.4 | <.0001 | .538 | .988 | |
| 9 | 97.7 | 67.5 | 165.2 | 166.0 | <.0001 | .597 | .985 | |
| 10 | 93.8 | 75.7 | 169.5 | 186.5 | <.0001 | .655 | .961 | |
| 11 | 88.2 | 82.5 | 170.7* | 199.7* | <.0001 | .713 | .934 | |
| 12 | 72.9 | 89.0 | 161.9 | 171.8 | <.0001 | .766 | .870 | |
| Cocaine | 6 | 98.9 | 88.9 | 187.8 | 251.0 | <.0001 | .724 | .996 |
| 7 | 97.8 | 91.5 | 189.3 | 271.2 | <.0001 | .772 | .993 | |
| 8 | 96.7 | 92.5 | 189.2 | 276.3 | <.0001 | .791 | .990 | |
| 9 | 95.6 | 93.8 | 189.4* | 285.7 | <.0001 | .819 | .986 | |
| 10 | 93.3 | 94.8 | 188.1 | 286.8* | <.0001 | .840 | .980 | |
| 11 | 88.9 | 96.1 | 185.0 | 282.3 | <.0001 | .870 | .967 | |
| 12 | 80.0 | 96.4 | 176.4 | 245.8 | <.0001 | .867 | .943 | |
| Marijuana | 5 | 100.0 | 52.1 | 152.1 | 6.34 | < .05 | .055 | 1.000 |
| 6 | 100.0 | 54.9 | 154.9 | 7.07 | < .01 | .058 | 1.000 | |
| 7 | 100.0 | 61.9 | 161.9 | 9.32 | < .01 | .068 | 1.000 | |
| 8 | 100.0 | 68.4 | 168.4* | 12.25 | <.0001 | .081 | 1.000 | |
| 9 | 83.3 | 74.4 | 157.7 | 9.84 | < .01 | .083 | .994 | |
| 10 | 83.3 | 80.0 | 163.3 | 13.78 | <.0001 | .104 | .994 | |
| 11 | 66.7 | 88.4 | 155.1 | 15.5 | <.0001 | .138 | .990 | |
| 12 | 66.7 | 92.6 | 159.3 | 24.9 | <.0001 | .200 | .990 | |
| 13 | 66.7 | 95.3 | 162.0 | 37.8* | <.0001 | .286 | .990 | |
| 14 | 33.3 | 97.2 | 130.5 | 15.6 | <.0001 | .250 | .981 | |
| Opiates | 2 | 91.7 | 93.4 | 185.1 | 103.3 | <.0001 | .289 | .997 |
| 3 | 91.7 | 94.6 | 186.3 | 120.8 | <.0001 | .333 | .997 | |
| 4 | 91.7 | 96.4 | 188.1* | 156.6 | <.0001 | .423 | .997 | |
| 5 | 83.3 | 96.8 | 180.1 | 145.7 | <.0001 | .435 | .995 | |
| 6 | 83.3 | 97.3 | 180.6 | 160.8 | <.0001 | .476 | .995 | |
| 7 | 83.3 | 98.5 | 181.8 | 214.8* | <.0001 | .625 | .995 | |
| 8 | 75.0 | 99.0 | 174.0 | 214.5 | <.0001 | .692 | .993 | |
| 9 | 75.0 | 99.0 | 174.0 | 214.5 | <.0001 | .692 | .993 |
*
The highest value; PPP: positive predictive potential; NPP: negative predictive potential.