AIMS: We tested whether patrons of the night-economy who had co-consumed energy drinks or illicit stimulants with alcohol had higher blood alcohol concentration (BAC) levels than patrons who had consumed only alcohol. DESIGN: Street intercept surveys (n=4227) were undertaken between 9pm-5am over a period of seven months. SETTING: Interviews were undertaken with patrons walking through entertainment precincts, queuing to enter venues, or exiting venues, in five Australian cities. PARTICIPANTS: The response rate was 92.1%; more than half of the study sample was male (60.2%) and the median age was 23 years (range 18-72). MEASUREMENTS: Data were collected on demographics, length of drinking session, venue types visited, types and quantity of alcohol consumed and other substance use. A BAC reading was recorded and a sub-sample of participants were tested for other drug use. FINDINGS: Compared to alcohol-only consumers (0.068%), illicit stimulant consumers (0.080%; p=.004) and energy drink consumers (0.074%; p<.001) had a significantly higher mean BAC reading, and were more likely to engage in pre-drinking (66%, 82% and 78% respectively, p<.001) and longer drinking sessions (4 hours, 5 hours and 4.5 hours respectively, p<.001). However, stimulant use was not independently associated with higher BAC in the final multivariable model (illicit stimulants p=.198; energy drinks p=.112). Interaction analyses showed that stimulant users had a higher BAC in the initial stages of the drinking session, but not after 4-6 hours. CONCLUSIONS: While stimulant use does not predict BAC in and of itself, stimulants users are more likely to engage in prolonged sessions of heavy alcohol consumption and a range of risk-taking behaviours on a night out, which may explain higher levels of BAC among stimulants users, at least in the initial stages of the drinking session.
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This study was supported by funding from the National Drug Law Enforcement Research Fund (NDLERF), National Health and Medical Research Council (NHMRC), Australian Research Council (ARC) and Victorian Health Promotion Fund (VicHealth).