Risk of injury after alcohol consumption from case-crossover studies in five countries from the Americas.

AIMS This study aimed to: (i) provide relative risk (RR) estimates between acute alcohol use and injuries from emergency departments (EDs) in the Dominican Republic, Guatemala, Guyana, Nicaragua and Panama, and (ii) test whether the RR differs if two control periods for the estimates were used. DESIGN Case-crossover methodology was used to obtain estimates of the RR of having an injury within 6 hours after drinking alcohol, using a pair-matching design with control periods of the same time of day on the day prior to injury, and the same time of day and day of week during the week prior to injury. SETTING EDs. PARTICIPANTS A total of 2503 injured patients from EDs were interviewed between 2010 and 2011, with a response rate of 92.6%. MEASUREMENTS Number of drinks consumed within 6 hours prior to the injury and in the two control periods. FINDINGS The RR of injury after drinking alcohol was 4.38 [95% confidence interval (CI): 3.29-5.84] using the prior week as the control period, and 5.35 (CI: 3.50-8.17) using the prior day as a control period. The RR was 5.08 (CI: 4.15-6.23) in multiple matching. Those drinking one to two drinks had a RR of 4.85 (CI: 3.12-7.54); those drinking three to five drinks an RR of 5.00 (CI: 3.47-7.18); those drinking six to 15 drinks an RR of 4.54 (CI: 3.36-6.14); and those drinking 16 or more drinks an RR of 10.42 (CI: 4.38-24.79). CONCLUSIONS As in other countries, drinking alcohol is an important trigger for an injury in the Dominican Republic, Guatemala, Guyana, Nicaragua and Panama.