Benzodiazepines and workplace safety: an examination of postaccident urine drug tests

Benzodiazepines were introduced for clinical use since the 1960s and rapidly became the sedative-hypnotic of choice. The purpose of this study was to determine whether benzodiazepine use as measured by drug tests is higher in postaccident drug tests than in random tests.

This is a case-control study comparing the proportion of benzodiazepine laboratory positive urine specimens for random versus postaccident samples. Any sample that tested positive for 1 or more substances other than benzodiazepines was eliminated from the study to correct for the confounding effect of other potentially impairing substances. The group prevalence of benzodiazepine positive samples was compared via the odds ratio with 95% confidence intervals and the P-values.

The study began with 4756 urine samples with 2161 postaccident specimens and 2595 random specimens. A total of 243 of the samples were confirmed positive for drugs other than benzodiazepines. The study was left with 2016 postaccident and 2497 random samples. In the controlled postaccident group, there were 57 positive screens and 17 (29.8%) were confirmed as positive for either a benzodiazepine or benzodiazepine metabolites. In the controlled random group, there were 48 positive screens and 10 (20.8%) were confirmed as positive for either a benzodiazepine or benzodiazepine metabolites. The OR comparing the total confirmed laboratory positive benzodiazepine specimens after controlling for other substances was 2.1150 (0.9663-4.6292) with a P-value of 0.0609.

The results for comparing the total confirmed laboratory positive benzodiazepine tests controlled for other substances, although suggestive of an association, did not achieve statistical significance.