UC Berkeley

Background and aims

Most studies reporting alcohol use among fatally injured victims are subject to bias, particularly those related to sample selection and to absence of injury context data. We developed a research method to estimate the prevalence of alcohol consumption and test correlates of alcohol use prior to fatal injuries.

Design, setting and participants

Cross-sectional study based on a probability sample of fatally injured adult victims (n = 365) autopsied in São Paulo, Brazil. Victims were sampled within systematically selected 8-hour sampling blocks, generating a representative sample of fatal injuries occurring during all hours of the day for each day of the week between June 2014 and December 2015.

Measurements

The presence of alcohol and blood alcohol concentration (BAC) were the primary outcomes evaluated according to victims' socio-demographic, injury context data (type, day, time and injury place) and criminal history characteristics.

Findings

Alcohol was detected in 30.1% [95% confidence interval (CI) = 25.6-35.1)] of the victims, with a mean blood alcohol level (BAC) level of 0.11% w/v (95% CI = 0.09-0.13) among alcohol-positive cases. Black and mixed race victims presented a higher mean BAC than white victims (P = 0.03). Fewer than one in every six suicides tested positive for alcohol, while almost half of traffic-related casualties were alcohol-positive. Having suffered traffic-related injuries, particularly those involving vehicle crashes, and injuries occurring during weekends and at night were associated significantly with alcohol use before injury (P < 0.05).

Conclusions

Nearly one-third of fatal injuries in São Paulo between June 2014 and December 2015 were alcohol-related, with traffic accidents showing a greater association with alcohol use than other injuries. The sampling methodology tested here, including the possibility of adding injury context data to improve population-based estimates of alcohol use before fatal injury, appears to be a reliable and lower-cost strategy for avoiding biases common in death investigations.