Abstracts

Rationale: We sought to understand the magnitude of the risk that drivers with epilepsy contribute to highway accidents, compared to other drivers. Methods: The question posed was do drivers with epilepsy (DWE) have higher rates of motor vehicle accidents (MVAs) than those without epilepsy? We performed a systematic, evidence-based review using the American Academy of Neurology (AAN) guideline methodology. We searched Pubmed for all articles published from 1996-present.The search strategy included the Boolean operator AND between the parenthetical statements (epilepsy OR seizure OR seizure disorder OR loss of consciousness) and (driving OR motor vehicle accident OR driving accident OR driving risk). This search yielded 494 abstracts. Twenty-eight papers were selected from these abstracts for further review, and were classified according to the AAN prognostic criteria. Results: The evidence consisted of one Class I study, six Class II studies and one Class III study. From one Class II study, seizure-related crashes are rare, occurring in 1 out of every 2800 MVAs (Drazkowski et al., 2003). From another Class II study, DWE are at least 50% less likely to be involved in fatal crashes than other drivers (Sheth et al, 2004). Fatal crashes due to alcohol abuse and to other medical conditions occur 156 times and 26 times respectively more often than fatal crashes in DWE (Sheth et al., 2004). A single Class I study by Sillanpaa and Shinnar, 2013 had small sample size and a 1 year assessment with no MVAs reported, therefore the results are not contributory. Three articles found no increased risk of overall MVA rates for DWE when compared with the general population with RR 0.86 (95% CI 0.65-1.14) from Taylor et al., 1996 (Class III), RR 1.00 (95% CI 0.95-1.06) from Mclachlan et al., 2007 (Class II), and RR 1.62 (95% CI 0.95-2.76) from Kwon et al., 2011 (Class II). Two Class II studies found an increased risk of overall MVA rates for DWE when compared with the general population with RR 1.73 (95% CI 1.58-1.90) from Vernon et al.,2002, and RR 7.01(95% CI 2.18-26.13) from Lings, 2001. The denominators used to derive these rates for all studies varied, and included billions of miles driven, person-years of driving, and license days. Conclusions: 1.Seizure-related crashes are rare, occurring in 1 out of every 2800 MVAs and occur much less than those due to alcohol abuse and other medical conditions. 2.DWE are at least 50% less likely to be involved in fatal crashes than other drivers. 3.The overall rates of MVAs were low but not consistent. Reasons for this include the following: a. Vernon et al.,2003 evaluated a relatively short period of driving restriction (three months) may have influenced the results toward more poorly-controlled DWE who had more MVAs. b. Two publications in which no increased risk was found were questionnaire surveys and the DWE may have underreported their MVAs. c. DWE have a tendency to drive less (Lings, 2001), therefore, years of driving may not be accurate as a denominator. 4.Future research should be performed using miles driven as the denominator to calculate MVA rates.