Objective: To study how the various 25 subtests and observations of the Norwegian clinical test for impairment related to the blood benzodiazepine concentrations of apprehended drivers suspected of driving under the influence of benzodiazepines. The impact of single-dose intake in non-daily users of benzodiazepines on the clinical picture of inebriation was also studied.
Methods: Included in the study were 818 drivers suspected of driving under the influence of non-alcoholic drugs with blood samples containing only one benzodiazepine. We determined which of the 25 subtests and observations of the clinical test for impairment related significantly to the blood benzodiazepine concentrations.
Results: Significantly related to blood benzodiazepine concentrations were 13 subtests and observations. Of these, 9 withstood adjustment for a variety of background variables. Single dose intake in non-daily users only influenced 3 subtests and observations after adjustment for blood benzodiazepine concentration and background variables. Romberg's test, 1 observation concerning alertness (oriented for time and place), 4 tests on motor and coordination (walk and turn on line, finger-to-nose and finger-to-finger tests), 2 observations on speech (articulation and content) and 1 observation regarding appearance (general conduct) were related to blood benzodiazepine concentrations.
Conclusion: Many of these simple clinical tests are included in the standardized field sobriety test and are of value in revealing benzodiazepine impairment. The present study offered some possible additions. Combinations of these robust tests can also be used to reveal benzodiazepine inebriation in other contexts.