Table 2.
Direct comparisons of test sensitivity and specificity compared to laboratory reference tests of THC in blood at varying positivity thresholds (ng/mL THC), as reported by 1 randomized experimental and 1 non-randomized observational comparative study of roadside tests for cannabis use.
| Screening Test (positivity threshold, ng/mL THC) | Study (sample) | Laboratory Reference Test (n tests; n reference test positives) | Sensitivity and specificity (% [95% CI]) at varying positivity thresholds (ng/mL THC) |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.2 |
0.5 |
1.0 |
2.0 |
5.0 |
10.0 |
27.0 |
||||||||||
| SENS | SPEC | SENS | SPEC | SENS | SPEC | SENS | SPEC | SENS | SPEC | SENS | SPEC | SENS | SPEC | |||
| Oral fluid screening tests vs. observational tests | ||||||||||||||||
| Alere DDS 2 (25) | Edwards 2017 (subjects arrested for an alleged OWI) | EIA and GCMS-NPD in blood (15; 9), | – | – | – | – | – | – | – | – | – | – | 88.9 (56.5–98.0) | 66.7 (30.0–90.3) | – | – |
| DRE evaluation (N/A) | – | – | – | – | – | – | – | – | – | – | 55.6 (26.7–81.1) | 66.7 (30.0–90.3) | – | – | ||
| Oral fluid screening tests vs. oral fluid screening tests | ||||||||||||||||
| Alere DDS 2 (25) | Newmeyer 2017 (adult occasional and frequent cannabis users) | LC-MS/MS in blood (DDS2: 134; 1.0: 78, 2.0: 41, 5.0: 21, 10.0: 11) | – | – | – | – | 43.6 (33.1–54.6) | 82.1 (70.2–90.0) | 65.9 (50.6–78.4) | 81.7 (72.7–88.3) | 85.7 (65.4–95.0) | 77.0 (68.4–83.8) | 81.8 (52.3–94.9) | 71.5 (63.0–78.8) | – | – |
| Draeger DrugTest 5000 (5) | LC-MS/MS in blood (103; 1.0: 72, 2.0: 53, 5.0: 19, 10.0: 10) | – | – | – | – | 34.7 (24.8–46.2) | 87.1 (71.2–94.9) | 43.4 (31.0–56.7) | 88.0 (76.2–94.4) | 73.7 (51.2–88.2) | 82.1 (72.6–88.9) | 70.0 (39.7–89.2) | 76.3 (66.8–83.8) | – | – | |
CI = confidence interval; DDS = Drug Detection System; DRE = Drug Recognition Expert; EIA = enzyme immunoassay; GCMS-NPD = gas chromatography mass spectrometry with nitrogen phosphorus detector; LC-MS/MS = liquid chromatography tandem mass spectrometry; OWI = operating while intoxicated; THC = delta-9-tetrahydrocannabinol.
Experimental studies are demarcated in bold. Crouch 2005, Walsh 2003, and Walsh 2007 were comparative in design but did not evaluate devices against the same reference test positivity thresholds and were thus excluded from this table.