Seizures and Driving: A Systematic Review of the
Evidence
Dr Carol Hawley Warwick Medical School and Professor Jane Hutton Department of Statistics
Clerical Assistance: Lynda Mason Warwick Medical School. Contact: c.a.hawley@warwick.ac.uk
Background
Seizures affect up to 10% of the population at
some point during their lifetime. Cumulative
incidence of epilepsy worldwide is at least 4%
(Hauser, 1996)
Driving Licensing authorities throughout the
world apply restrictions on those who have
seizures, but the seizure-free period required
before a driving licence is restored varies
between countries.
Restrictions are based on judgements of the risk
of further seizures which could affect road
safety.
The European Working Group (1996) states that
rules must be liberal, simple, clear and based on
calculated risk.
The European Directive sets out standards for
driving and epilepsy. EU member states can be
more restrictive but not more liberal.
In the UK an unprovoked seizure triggers a 12
month driving ban (up until 1994 it was a 2 year
ban).
Study Aims
To conduct a systematic review of the existing
literature (academic papers and 'grey' literature
and research in progress) relating to the
probability of further seizures occurring at
various time intervals after an initial seizure or
seizure provoking incident such as head injury,
neurosurgery, tumour or stroke.
UK Medical Standards
Group 1 drivers: after a ‘first epileptic seizure or
solitary fit’, Cease driving for one year and then
be submitted for medical review before restarting driving. The licence may then be
restored until age 70 provided that there is no
further attack and the driver is otherwise
medically well.
Seizure Legislation Around the World
Seizure free period before return of driver's licence
INDIA (proposed)
PORTUGAL
CROATIA
SWEDEN
AUSTRALIA
JAPAN
USA
SWITZERLAND
BELGIUM
GERMANY
UK
USA: WISCONSIN
0
6
12
18
24
30
Unprovoked Seizures
The Way Forward?
The overall risk of recurrence of seizures by
one year after a first unprovoked seizure ranged
from 16% to 67% depending on the duration of
follow-up, method of case ascertainment,
definition of seizure, and population studied.
No reliable estimates of risk can be given by
type of seizure.
Different rules for different seizures. Proposed
by 2nd European Working Group on Epilepsy
and Driving; (2005).
36
Systematic review of the literature from 1966
to present, including foreign language articles.
Seizures of all causes and all risk factors were
included and co-morbidities (including alcohol
related health issues) were considered.
Anonymised abstracts screened by 4
independent researchers.
Data were extracted relating to the
probabilities of recurrent seizures over varying
time periods.
Data synthesised and risk estimates
calculated.
Broad eligibility criteria were applied at the
abstract screening stage:
1. Studies of seizures in previously seizure free
individuals
2. Studies of predominantly adults
3. Studies which reported numerical data
4. Studies which appeared to assess risk of
subsequent seizures after an initial seizure
Post-traumatic seizure: An initial or recurrent
seizure episode not attributable to another
obvious cause after penetrating or nonpenetrating TBI.
Late post-traumatic seizure: Occurring after
the first week of injury.
Epilepsy: A condition characterised by
recurrent seizures.
 TBI accounts for 5% of all cases of epilepsy
(Hauser et al, 1991).
 21 studies of TBI met inclusion criteria for the
review, only 13 provided data in a form suitable
for meta-analysis.
 Risk of seizures per person per year declines
with increasing time without seizures after injury.
 Mild TBI is associated with a low risk of
seizures.
 Conservative estimate: 8% of people with
severe TBI will have a seizure in the first year
after their injury (Hawley & Hutton, 2010).
Evidence suggests that drivers with a history
of epilepsy are no more likely to have an
accident whilst driving than drivers without a
history of epilepsy (Chadwick, 1996).
But the at-risk group of non-reporters are
young drivers who are 10 times more likely to be
involved in a serious collision than more
experienced drivers. (RoSPA).
Most accidents occur to 17 – 24 year olds,
mostly males (DfT Road Casualties GB 2007).
(Jennett, 1995)
Conclusions
35
35
30
25
25
17
yes
no
15
10
5
3
4
5
0
Early seizures Depressed Skull
Fracture
Intercranial
haematoma
Risk of Accidents and Seizures
Compliance with Seizure Laws
 Drivers don’t always report their seizures to
physicians or to the licensing authorities.
 Non-reporters more likely to be young, male,
inexperienced drivers with increased accident
risk than those who DO report (e.g. Taylor et al,
1995).
 Norfolk study (Dalrymple and Appleby, 2000):
1/6th of patients had not reported recent
seizures to their GP.
 40% of patients who anonymously reported
seizures to researchers also held a current
driving licence, but only 1/4 had told their GP.
 Berg et al (2000): 1/3 epilepsy patients drove
regularly despite frequent seizures.
 Compliance can only be increased if we can
give an explanation of the risk-increase in terms
that are understandable and convincing for the
patient.’ (2nd European Working Group on
Epilepsy and Driving; 2005).
The QUOROM statement flow
diagram
Quality of Evidence
The standard of reporting was poor in many of
the studies reviewed.
The majority of studies had research
objectives which differed from the research
question being addressed in this systematic
review.
Few studies specifically addressed seizure
recurrence in a systematic manner.
Of the 343 full-text papers reviewed, seizure
recurrence was the main focus of the research
for only 39 papers.
Different follow-up periods, patient groups.
 Patients have a legal duty to notify DVLA
about any condition that may affect his or her
ability to drive.
 Doctors (and other health professionals (HP))
should advise their patients that they should
notify DVLA and must cease driving. (General
Medical Council).
 If patient refuses, then doctor (or HP) may
disclose medical information to DVLA in
confidence and write to patient informing them
of this. www.dvla.gov.uk
 EU Working Group: Physician should not be
obliged to report patient to authorities as it:
•increases non-compliance
with regulations
•increases nonreporting of seizures to
the physician
•interferes with medical
treatment.
Risk factors for late seizures post-TBI
20
Results
Notification to Licensing Authorities
Are people with epilepsy high risk drivers?
%
Group 2 drivers: After a first unprovoked seizure,
Group 2 drivers must demonstrate 10 years
freedom from further seizures, without the aid of
anticonvulsant medication in that time.
Epilepsy:
Grp.1:12 month seizure free period.
Grp.2:10 years seizure free without AED
Risk of Seizures after TBI
months
Methods
First unprovoked seizure:
Grp.1: 6 month seizure free period &
appropriate medical assessment.
Grp.2: 5 years seizure free without aid of AED
 700 / million population have a 1st seizure
(Jallon, 2001).
 In 1st year after 1st Seizure:
 55% of people not taking anti-epileptic drugs
(AEDs) will have a second seizure (Elwes et al,
1985; FIRST, 1993).
 33% of people taking AEDs will have a
second seizure (FIRST, 1993).
Car drivers spend an average of 1 hr/day
driving (4% of lifetime).
 Seizures can occur at any time in 24 hrs
therefore for car drivers there is a 1 in 24 chance
that a seizure will occur whilst driving.
 Professional drivers spend up to 8 hrs/day
driving (20% of lifetime). Therefore they have a 1
in 3 chance of a seizure whilst driving.
 About 50 - 60% of seizures behind the wheel
result in an accident (Sonnen, 1993).
Extrapolating from the 700/million population
who have an initial seizure: half (350 people) will
have a second seizure and 15 of these will be
driving when they have that seizure. For 60%
that seizure will cause an accident. Therefore:
8.8 people / million population will suffer a
seizure which will cause an accident in the first
year after their first seizure.
Despite this low risk most countries impose a
minimum of a 12 month driving ban after an
initial seizure.
The wide variation in the seizure free interval
after a first seizure before driving can resume,
applied by licensing agencies throughout the
world, reflects the limited scientific data
available on driving with seizures or epilepsy.
This variation may also relate to the politics of
road safety or to historic decisions that are
difficult to change without clear evidence.
This review found no new evidence for
revision of the DfT current estimates of seizure
risk.
New studies are needed to obtain better
information on risks of seizures in those with
predisposing factors. Such studies must have
very clearly specified questions and intensive
follow-up of patients.
Latest Research
A large MRC funded Multi-centre trial for early
Epilepsy and Single Seizures (MESS) was
published in 2005 (Marson et al. 2005, Lancet).
More seizures patients had prior to
randomisation = higher the risk of recurrent
seizures.
MESS data is being used to generate
estimates of risk of seizure recurrence for
individual patients and should provide good
estimates of the probability of future seizures
after an initial seizure. (Hutton, Johnson &
Marson).
References
•Chadwick D. (1996) Risk of accidents in drivers with epilepsy. Journal of Neurology,
Neurosurgery and Psychiatry, 60(6): 621-627.
•Department for Transport (2008) Road Casualties Great Britain: 2007. London.
•Darymple, J and Appleby J. (2000) Cross sectional study of reporting of epileptic seizures to
general practitioners. British Medical Journal, 320: 94-97.
•Elwes RDC et al (1985) Prognosis after a first untreated tonic-clonic seizure. Lancet 326
(8458):752-753.
•First Seizure Trial Group (FIRST Group) (1993) Randomized clinical trial on the efficacy of
antiepileptic drugs in reducing the risk of relapse after a first unprovoked tonic clonic seizure.
Neurology 43:478–483.
•General Medical Council. A-Z of Ethical Guidance. 2010.
•Hauser, WA, Annegers, JF, Kurland, LT. (1991) Prevalence of epilepsy in Rochester, Minnesota:
1940-1980. Epilepsia, 32: 429-445.
•Hauser, WA, Annegers, JF, Rocca, WA. (1996) Descriptive epidemiology of epilepsy:
contributions of population-based studies from Rochester, Minnesota. Mayo Clinic Proceedings,
71: 578-586.
•Hawley C and Hutton J. Road Safety Web Publication No.5: Systematic review of the probability of
future seizures after an initial seizure or other event creating an increased future risk. January
2010. Department for Transport, London.
•Jallon, P et al (2001) Newly Diagnosed Unprovoked Epileptic Seizures: Presentation at Diagnosis
in CAROLE Study Epilepsia, 42(4):464-475.
•Jennett, B. (1995) Epilepsy and neurosurgical disorders. In Epilepsy: Hopkins, A., Ed. 2nd Edn.
London: Chapman and Hall.
•Marson A, Jacoby A, Johnson A, Kim L, Gamble C, Chadwick D, on behalf of the Medical
Research Council MESS Study Group (2005) Immediate versus deferred antiepileptic drug
treatment for early epilepsy and single seizures: a randomised controlled trial. Lancet, 365: 200713.
•Second European Working Group on Epilepsy and Driving. Epilepsy and Driving in Europe. 2005.
•Sonnen, AEH (1993) The risk of epilepsy in daily life. In: C. M. Cornaggia CM, et al. Eds, Epilepsy
and Risks: A First-step Evaluation, Ghedini Editore, Milano.101–112.
•Taylor, J. (1995) The older driver. In Taylor JF (ed.) Medical Aspects of Fitness to Drive. A Guide
for Medical Practitioners. London: The Medical Commission on Accident Prevention 1995.