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From: Robert Swotinsky MD
Date: 04 Feb 2005
Time: 08:43:47 -0800
Remote Name: 4.17.131.55
I have data for the "NIDA-5" drugs as follows:
| Initial test assay confirmation rates | amphetamines | cocaine metabolites | opiates | PCP | Marijuana metabolite |
| mean rate | 51.9% | 98.1% | 30.2% | 69.7% | 91.0% |
| lowest rate | 37.4% | 91.1% | 17.3% | 51.6% | 73.0% |
| highest rate | 77.8% | 99.9% | 55.9% | 91.0% | 98.8% |
What you see here is, of those specimens that screen positive by immunoassay, the percentage of specimens that also confirm positive by GC/MS. The citation for these data is: Bush DM, et al. Confirmation rates of initial drug assays in a group of HHS-certified laboratories. January 01 through December 31, 2003. - 1. Federally regulated specimens. Presented at: Joint meeting of the Society of Forensic Toxicologists and the International Association of Forensic Toxicologists. Washington, DC. 2004.
Your question really asks about confirmation rates for benzodiazepine results. I believe that data that responds to your question was presented at the same conference where the above-referenced data was presented. However, the data on benzodiazepine (and other "non-NIDA") confirmation rates is complex and hard to interpret, since there are no standard cutoffs or standard target molecules for benzodiazepine analyses. I don't have the benzodiazepine data to post. If you really need it, you may be able to get a copy of that data from SAMHSA's drug testing office.