Citation

Rehm J, Shield KD, Vos T, Murray CJ, Lim S. Lancet 2013; 382(9898): 1093.

Comment On:

Lancet 2013;382(9898):1092-3.

Copyright

(Copyright © 2013, Elsevier Publishing)

DOI

10.1016/S0140-6736(13)62015-2

PMID

24075042

Abstract

We thank Guoqing Hu and Keita Mamady for their comments in which they present evidence from four countries on the number of people fatally injured by drivers with blood alcohol concentrations (BACs) above various thresholds, and compare these estimates to estimated alcohol-attributable fatalities from the 2010 Global Burden of Disease (GBD) study. The BAC derived data indicate a higher attribution of traffic fatalities to alcohol use than was estimated in the GBD 2010. However, for traffic fatalities, a person having a BAC above a certain threshold does not indicate causality, nor does a person having a BAC below a certain threshold indicate that alcohol use did not have a causal role in the accident. For example, while alcohol use might affect reaction time and other cognitive processes for people with a BAC ≥0·03 g/L, this does not mean that all injury fatalities involving such BACs are caused by alcohol use. The same is true for higher levels of BAC, with a BAC ≥0·1 g/L not implying causality, even though this threshold has been used as an indicator of injuries caused by alcohol use.

An alternative explanation for at least part of the association between alcohol use and injuries is that personality factors, such as sensation seeking, can affect both risky drinking and risky driving behavior. When measuring the effect of alcohol on the risk of injury, such alternative explanations can only be excluded if personality factors are controlled for, for instance by use of risk relations from case-crossover studies when calculating alcohol-attributable fractions (see Goodarz Danaei and colleagues' report for example). While not perfect, the approach used to calculate alcohol-attributable traffic injuries in the GBD 2010 is based on relative risks from more controlled studies. Thus, the current GBD methods are preferable when compared with an approach that bases causality solely on a BAC threshold; however, these methods lead to more conservative estimates. This is partly due to GBD methods relying on population survey data which underestimate the frequency of risky drinking occasions. Thus, for the next iteration of the GBD study, researchers should strive to further refine the methods used to estimate the number of alcohol-attributable road traffic injuries by correcting for the underestimation of survey-based exposure data as well as by including factors which may mediate the alcohol-injury relationship (such as road conditions).

We declare that we have no conflicts of interest.

Language: en