Estimating the Risk of Cardiac Mortality After Exposure to Conducted Energy Weapons

Conducted energy weapons (CEWs), commonly known as Tasers, are a reputed nonlethal law enforcement weapon. Nevertheless high profile cases have suggested a causal association with cardiac death but the magnitude of any putative risk is unclear.

An electronic systematic review of all real world, cohort studies of consecutive CEW cases was performed. "Pessimistic" and "optimistic" previous beliefs about CEW mortality were derived from an unbounded internet search, including case series but excluding the previously identified cohort publications. A Bayesian analysis updated these previous beliefs with the published objective cohort data.

Pessimistic and optimist previous beliefs with modes of 1/700 and 1/7000, respectively, and upper limits (< 2.5% probability) of 1/100 and 1/1000, respectively, were constructed. Three cohort studies formed the objective data source and their combined mortality was 1 in 2728 cases or 3.67/10,000 (95% confidence interval, 1/107,751 - 1/490). The maximum a posteriori estimated risks of CEW mortality for the pessimistic and optimistic prior distributions were 5.3 and 2.2 deaths per 10,000 exposures, respectively. The upper limits (< 1% probability of occurrence) of the posterior distribution were 1 death per 408 and 982 CEW exposures for the pessimistic and optimistic previous beliefs, respectively.

Limited available evidence can be used to construct approximate boundaries for CEW mortality risk and suggests that the population risk of CEW mortality is likely small but not negligible. More high quality data are required to refine these estimates and extreme caution must be exercised before applying these population risks to individual cases.