Employers who are not subject to the federal drug-testing regulations may include drugs and drug classes in their testing programs that are not included in the HHS 5 drug panel. Additional drug classes commonly tested include barbiturates and benzodiazepines. Other individual drugs tested for include methadone, methaqualone, propoxyphene, and, occasionally, synthetic opiates such as hydrocodone, hydromorphone, and oxycodone. Ethyl alcohol is also sometimes included in an expanded drug-testing panel. Alcohol, discussed later in this chapter, is not tested for under the DHHS guidelines, but it is tested for using evidentiary breath-testing methodology under DOT regulations since January 1995.
The incidence of documentable abuse or illegal use of the drugs not included in the DHHS/DOT programs is somewhat lower than for those that are. In 2004, DAWN Final Estimates indicated that reported Emergency Department visits that mentioned drugs as a cause mentioned illicit drugs 30% of the time, pharmaceuticals 25% of the time. Cures of illicit drugs and pharmaceuticals were mentioned 8% of the time, illicit drugs and alcohol 15% of the time, and a mixture of all 3.14% of the time.
NRC tests for barbiturates and benzodiazepines as a part of its Fit for Duty program and NRC regulations specify that the MRO must determine that there is clinical evidence of unauthorized use of benzodiazepines or barbiturates before verifying a positive result. Some of these medications, especially benzodiazepines, are frequently shared between friends and relatives, which can lead to difficult decisions for MROs. The low incidence of validated illegal use for some of these drugs might be due to the frequency with which they are prescribed. Some physicians prescribe benzodiazepines chronically for questionable reasons, perhaps because they are considered safe.
Walsh et al. studied 3 years of results reported by a large MRO organization and found that in the nonregulated dataset, a significantly high number of laboratory-confirmed positive results were ultimately reported by the MRO as negative to the employer. These were for benzodiazepines (74.57%) and barbiturates (83.66%). These data axe reflective of the MRO practice of reporting a test as negative if the individual is able to produce a valid, current script for a drug that could have caused the confirmed positive test result.
The MRO should be aware of several major differences between drug testing using the ELMS F. drug panel and other expanded drug panels. Laboratory procedures for drug testing not governed by DHHS/DOT regulations have not been standardized. Therefore, the MRO might encounter variable immunoassay and confirmation cutoff concentrations. In addition, the actual drug/metabolites confirmed within a drug class, the instrumentation used for confirmation, and the number and type of quality control specimens used by the laboratory for these analytes can vary. Some laboratories may not even use a confirmation procedure, or may use one type of immunoassay test to confirm another. Finally, drug screens that test for additional drugs simultaneously with the HHS 6 drug panel do not fall under DHHS/DOT authority; consequently, many laboratories do not perform the testing for the HHS 5 panel under the federal guidelines and requirements. As a result, the variables described above could apply to the HHS 5 panel drugs as well.
Important variables specific to certain additional drugs are discussed in the following sections. The MRO may need to investigate the laboratory procedures, including target analytes and cutoff levels, to correctly review and interpret positive results for these drugs.