A systematic review and meta-analysis of alcohol consumption and injury risk as a function of study design and recall period.

BACKGROUND

It is well established that alcohol consumption is associated with an increased risk of injury. This systematic review and meta-analysis addresses important methodological issues commonly encountered in the alcohol and injury field by delineating the effect of study design and alcohol consumption recall period on effect size magnitude and by conducting gender-specific analyses.

METHODS

We performed meta-analyses using random-effect models. Data sources were peer-reviewed studies on alcohol and injury from 1970 to 2009 from MEDLINE, PsychInfo, and on-line journals. Case-control or case-crossover emergency department (ED) studies reporting injury risk from alcohol consumption 6 hours before injury were included.

RESULTS

The overall odds of injury were 2.799 (2.214 to 3.538, p < 0.001). For case-crossover studies, the odds were 3.815 (2.646 to 5.499, p < 0.001); for ED case-control studies, the odds were 1.977 (1.385 to 2.821, p < 0.001); and for population case-control designs, the odds were 3.145 (1.583 to 6.247, p < 0.005). The "usual frequency" recall period yielded an odds ratio of 4.235 (2.541 to 7.057, p < 0.001), compared to 2.320 (1.789 to 3.008, p < 0.001) for all other methods. There were significant differences in odds ratio magnitude when comparing studies by design and recall period. Females had higher odds of injury than males, 2.285 (1.361 to 3.836, p < 0.005) versus 1.071 (0.715 to 1.605, p = 0.737).

CONCLUSIONS

Study design and alcohol consumption recall period have significant effects on effect size magnitude in estimating the risk of injury from alcohol consumption 6 hours prior to injury. For the "usual frequency" case-crossover design, significant moderator effects were found, resulting in overestimates of injury risk from alcohol. ED case-crossover designs tend to overestimate risk, and ED case-control designs tend to underestimate. We provide recommendations for future ED research.