Comparison of the prevalence of substance use and psychiatric disorders between government- and self-employed commercial drivers.

Five hundred and five city government-employed bus drivers (GED) and 506 self-employed drivers (SED) who were primarily taxi drivers attending annual health check-ups were studied. A two-step survey was applied. Data on basic demographics were collected, the 12-item Chinese Health Questionnaire (CHQ), Michigan Alcoholism Screening Test (MAST), Drug Abuse Screen Test (DAST) questionnaires were administered and urine drug screening for amphetamine and benzodiazepines was performed in all subjects. Subjects with MAST scores > or =3, DAST > or =5 from both groups and CHQ > or =4 for the GED group and CHQ > or =7 for the SED group were regarded as a high-risk group; and subjects with normal MAST, DAST and CHQ results serving as the comparison group were invited for further interview by psychiatric specialists using the Mini International Neuropsychiatric Interview. The mean CHQ scores were 0.94 +/- 1.53 for the GED group and 2.08 +/- 2.42 for the SED group. The mean MAST scores for the GED and SED groups were 0.23 +/- 0.58 and 0.38 +/- 1.12; and the mean DAST scores were 1.03 +/- 0.85 and 1.41 +/- 1.89, respectively. The positive rate for benzodiazepines in urine screening by enzyme immunoassay was 8.3% for the GED group, and 8.5% for the SED group. After specification using liquid chromatography, this rate reduced to 4.6% and 3.7%, respectively. Only one subject in the SED group tested positive for urine amphetamine. The SED group had a higher rate of neurotic problems, psychiatric diagnosis and a higher frequency of substance use than the GED group. These findings suggest that different work style of commercial drivers may contribute to this phenomenon. The rate of psychiatric diagnosis was significantly higher in the high-risk subjects from both groups. Questionnaires such as CHQ, DAST and MAST are useful tools to screen out subjects at high risk of psychiatric disorders during routine health checks in labor workers.