Table 2.
Accuracy of Craving as the Sole Predictor of Ongoing Methamphetamine Use.
| Number of weeks following craving assessment (endpoint) | |||||||
|---|---|---|---|---|---|---|---|
|
|
|||||||
| Summary statistic | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Sample characteristics | |||||||
| Number of observations (N) | 2742 | 2342 | 1875 | 1449 | 1031 | 675 | 309 |
| Number of subjects (n) | 691 | 652 | 601 | 574 | 496 | 443 | 309 |
| Prevalence of use | 0.30 | 0.27 | 0.28 | 0.29 | 0.28 | 0.28 | 0.29 |
| Prevalence of nonuse | 0.70 | 0.73 | 0.72 | 0.71 | 0.72 | 0.72 | 0.71 |
| Craving score (Mean/SD) | 17/31 | 20/33 | 20/33 | 21/34 | 22/35 | 25/35 | 28/37 |
| Craving score = 0 (%) | 21 | 23 | 26 | 31 | 37 | 44 | 58 |
| Craving score = 100 (%) | 3 | 3 | 3 | 3 | 4 | 4 | 5 |
| Predictive accuracy | |||||||
| Area under the curve (AUC) | 0.70 | 0.70 | 0.68 | 0.64 | 0.63 | 0.60 | 0.58 |
| Optimal craving cut-off point | 27 | 25 | 30 | 33 | 34 | 50 | 70 |
| Sensitivity (Sn) | 0.47 | 0.48 | 0.45 | 0.43 | 0.46 | 0.32 | 0.26 |
| False negative (FN) rate | 0.53 | 0.52 | 0.55 | 0.57 | 0.54 | 0.68 | 0.74 |
| Specificity (Sp) | 0.82 | 0.81 | 0.81 | 0.80 | 0.78 | 0.80 | 0.81 |
| False positive (FP) rate | 0.18 | 0.19 | 0.19 | 0.20 | 0.22 | 0.20 | 0.19 |
| Positive predictive value (PPV) | 0.52 | 0.52 | 0.49 | 0.46 | 0.46 | 0.39 | 0.36 |
| Change in likelihood | 0.22 | 0.25 | 0.21 | 0.17 | 0.18 | 0.11 | 0.07 |
| Negative predictive value (NPV) | 0.79 | 0.79 | 0.79 | 0.77 | 0.79 | 0.75 | 0.73 |
| Likelihood use despite - | 0.21 | 0.21 | 0.21 | 0.23 | 0.21 | 0.25 | 0.27 |
| Change in likelihood despite - | −0.09 | −0.06 | −0.07 | −0.06 | −0.07 | −0.03 | −0.02 |
| Overall correctly classified | 72% | 71% | 71% | 69% | 69% | 67% | 65% |
| Predictive efficiency | |||||||
| Negative likelihood ratio (LR−) | 0.65 | 0.64 | 0.68 | 0.72 | 0.69 | 0.85 | 0.92 |
| Positive likelihood ratio (LR+) | 2.59 | 2.55 | 2.38 | 2.09 | 2.13 | 1.61 | 1.37 |
| Pre-assessment odds use | 0.43 | 0.37 | 0.39 | 0.41 | 0.39 | 0.39 | 0.41 |
| Rule-in use (marker ≥ cut-off) | |||||||
| Post-assessment odds use | 1.11 | 0.94 | 0.93 | 0.85 | 0.83 | 0.63 | 0.56 |
| Change in odds of use | 0.68 | 0.57 | 0.54 | 0.44 | 0.44 | 0.24 | 0.15 |
| Post-assessment probability use | 0.59 | 0.49 | 0.46 | 0.46 | 0.45 | 0.39 | 0.36 |
| Change in probability use | 0.29 | 0.22 | 0.18 | 0.17 | 0.17 | 0.11 | 0.07 |
| Rule-out use (marker < cut-off): | |||||||
| Post-assessment odds use | 0.28 | 0.24 | 0.26 | 0.29 | 0.27 | 0.33 | 0.38 |
| Change in odds use | −0.15 | −0.13 | −0.13 | −0.12 | −0.12 | −0.06 | −0.03 |
| Post-assessment probability use | 0.22 | 0.19 | 0.21 | 0.23 | 0.21 | 0.25 | 0.27 |
| Change in probability use | −0.08 | −0.08 | −0.07 | −0.06 | −0.07 | −0.03 | −0.02 |