Table 2 Diagnostic performance of ∆HU for 2 levels of cocaine content
Variable | Sensitivity | Specificity | Positive predictive value | Negative predictive value | Odds ratio (95 % confidence interval) |
|---|---|---|---|---|---|
Cocaine content >35 % | |||||
∆HU >130 | 0.79 (19/24) | 0.77 (23/30) | 0.73 (19/26) | 0.82 (23/28) | 12.5 (3.4–45.7) |
∆HU >140 | 0.75 (18/24) | 0.80 (24/30) | 0.75 (18/24) | 0.80 (24/30) | 12.0 (3.3–43.4) |
∆HU >150 | 0.71 (17/24) | 0.87 (26/30) | 0.81 (17/21) | 0.79 (26/33) | 15.8 (4.0–62.3) |
Cocaine content >50 % | |||||
∆ HU >200 | 0.90 (9/10) | 0.82 (36/44) | 0.53 (9/17) | 0.97 (36/37) | 40.5 (4.5–366.8) |
∆ HU >250 | 0.80 (8/10) | 0.84 (37/44) | 0.53 (8/15) | 0.95 (37/39) | 21.1 (3.7–121.4) |
∆HU >300 | 0.70 (7/10) | 0.91 (40/44) | 0.64 (7/11) | 0.93 (40/43) | 23.3 (4.3–127.6) |