Evaluation of a roadside impairment test device using alcohol

Area of Science:

• Forensic Science
• Toxicology
• Public Health

Background:

• Roadside impairment tests are crucial for detecting impaired driving.
• Current field impairment tests (FIT) may exhibit age-related biases.
• A need exists for accurate and reliable impairment detection devices.

Purpose of the Study:

• To compare the diagnostic accuracy of the roadside impairment testing apparatus (RITA) against standard field impairment tests (FIT).
• To investigate the influence of age on the performance of RITA and FIT.
• To evaluate the potential of horizontal gaze nystagmus (HGN) as a roadside impairment indicator.

Main Methods:

• A two-period crossover study involving 122 healthy volunteers (aged 18-70).
• Volunteers consumed alcohol or placebo, with blood alcohol concentrations targeted at 90 mg/100ml.
• Roadside impairment testing apparatus (RITA), field impairment tests (FIT), and horizontal gaze nystagmus (HGN) were administered 30-75 minutes post-consumption.

Main Results:

• Field impairment tests (FIT) demonstrated a diagnostic accuracy of 62.7% with significant age-related bias.
• Roadside impairment testing apparatus (RITA) accuracy ranged from 66-70%, not significantly higher than FIT, but showed no marked age effect.
• Horizontal gaze nystagmus (HGN) achieved 74% accuracy.

Conclusions:

• Roadside impairment testing apparatus (RITA) offers a potential advantage over FIT by reducing false positives due to age.
• While RITA's accuracy is comparable to FIT, its lack of age bias warrants further consideration for roadside deployment.
• Horizontal gaze nystagmus (HGN) shows promise as a component of UK roadside impairment testing, meriting further research with various substances.