Written evidence from the National Institute
for Health and Clinical Excellence (NICE) (DDD 37)
SUMMARY OF
KEY POINTS
1. Overall, the evidence indicates that
lowering the UK BAC limit from 0.08 to 0.05 is likely to
reduce the number of alcohol-related deaths and injuries.
2. It could have an impact on the drink-driving
behaviour of everyone who drinks alcohol—including those
who tend to drink well above the current limit before driving.
However, the effect of lowering the BAC limit (in terms of scale
and sustainability) is likely to be dependent on increasing the
public's awareness and understanding of BAC limits and the rigour
of enforcement strategies. Currently, the actual—and perceived—risk
of being detected and sanctioned for drink-driving (in the context
of the BAC 0.08 limit) is low, and therefore does not act as a
sufficiently strong deterrent.
3. The effect is also likely to be dependent
on the precise combination of measures (including sanctions) targeting
specific groups of drink-drivers, particularly those who drink
and drive persistently above the limit.
4. Specific additional measures used in
combination with a lower BAC limit are likely to enhance the effect.
Administrative licence suspensions have proved an effective deterrent
as they are employed immediately after the offence. Zero tolerance
laws and graduated licensing systems for young drivers have also
proved effective.
5. The NICE review is based on a rigorous
review of the best available evidence. However much of this evidence
is from the USA, Australia, and other European countries. The
precise impact of these measures in the UK is uncertain, given
differences in the context. Nevertheless the review findings provide
an important basis for informing the government's policy considerations
on changes in drink driving legislation.
6. NICE would be happy to make on oral submission
of the evidence if requested.
ABOUT NICE
7. NICE is the independent organisation
responsible for providing national guidance on the promotion of
good health and the prevention and treatment of ill health. NICE
produces guidance mainly in three areas of health: public health
(guidance on the promotion of good health and the prevention of
ill health for those working in the NHS, local authorities and
the wider public and voluntary sector), health technologies, and
clinical practice. NICE guidance helps to improve the public's
health and makes access to healthcare more equitable across the
country.
INTRODUCTION
8. The Centre for Public Health Excellence
at NICE conducted a review of the evidence relating to drink driving
(NICE 2010).[54]
This review was commissioned by the Department for Transport.
It was considered by Sir Peter North as part of his independent
Review of Drink and Drug Driving law (June 2010).
9. This submission is based primarily on
the executive summary that sets out the findings of the NICE review.
It addresses the first of the issues the Committee is interested
in: Should the permitted blood alcohol limit be reduced from 80mg/100ml
to 50mg/100ml?
REVIEW OF
THE EVIDENCE—APPROACH
10. The review aimed to assess how effective
the blood alcohol concentration (BAC) laws are at reducing road
traffic injuries and deaths. It also assessed the potential impact
of lowering the BAC limit from 0.08 to 0.05.[55]
The findings will support the national road safety strategy for
2010 onwards for England and Wales.
11. The review examined:
— drink-driving patterns and the associated
risk of being injured or killed in a road traffic accident
— how BAC limits and related legislative
measures have changed drink-drinking behaviour and helped reduce
alcohol-related road traffic injuries and deaths
— models estimating the potential impact
of lowering the BAC limit from 0.08 to 0.05 in England
and Wales
— lessons from other countries on using
BAC laws as part of overall alcohol control and road safety policies.
12. The review was conducted in accordance
with the methods outlined in NICE's "Methods for development
of NICE public health guidance (second edition, 2009)" available
from www.nice.org.uk/phmethods
QUALITY OF
THE EVIDENCE
13. The evidence comes primarily from the
US, Australia, New Zealand and other European countries (mostly
Scandinavia) and it is difficult to determine how applicable the
findings are to the UK. There are marked historical, institutional,
social and cultural differences between countries, as well as
different political and policy priorities in relation to traffic
safety, alcohol consumption and drink-driving.
14. Any evaluation of the effectiveness
of BAC laws and related measures has certain limitations. In part,
this is due to the complex nature of such interventions. It is
also due to the methodological difficulties involved in conducting
rigorous evaluations of the impact of legislative measures on
a population. As a result, it is difficult to attribute precisely
reductions in alcohol-related injuries and deaths to changes in
BAC limits.
15. The quality of studies is also variable.
The best available evidence is provided by time series studies
(examining weather an "effect" was observed from date
of policy change) and multivariate regression analyses, a statistical
method that attempts to control for confounding factors. These
factors include underlying trends in alcohol consumption and economic
and social changes, as well as other alcohol control and road
safety policies.
FINDINGS OF
THE REVIEW
16. The main findings of the review are
presented below.
Drink-driving and the risk of a road traffic
accident
There is strong evidence that someone's ability
to drive is affected if they have any alcohol in their blood.
Drivers with a BAC of between 0.02 and 0.05 have at
least a three times greater risk of dying in a vehicle crash than
drivers with no alcohol in their blood. This risk increases to
at least six times with a BAC between 0.05 and 0.08, and
to 11 times with a BAC between 0.08 and 0.10.
17. Studies consistently demonstrate that
the risk of having an accident increases exponentially as more
alcohol is consumed.
18. Younger drivers are particularly at
risk of crashing whenever they have consumed alcohol—whatever
their BAC level—because they are less experienced drivers,
are immature and have a lower tolerance to the effects of alcohol
than older people.
19. Younger drivers may also be predisposed
to risk-taking—regardless of whether or not they have drunk
alcohol.
Effectiveness of BAC laws
Overall, there is sufficiently strong evidence
to indicate that lowering the legal BAC limit for drivers does
help reduce road traffic injuries and deaths in certain contexts.
20. A number of studies indicate that lowering
the BAC limit from 0.10 to 0.08 reduces road traffic
injuries and fatalities, although the scale of effect varies.
They include high quality review evidence (Shults et al. 2001).
The effect is independent of other control measures (in particular,
administrative licence suspension or revocation, which involves
immediate revocation or suspension of the driver's driving licence
upon failure of a breath test)..
21. Other studies indicate that reducing
the BAC limit from 0.08 to 0.05 is effective. In what is
the most recent and relevant high quality study, the adoption
of a 0.05 BAC driving limit reduced alcohol-related driving death
rates by 11.5% among young people aged 18-25 (Albalate 2006).
It also reduced driving fatalities among men of all ages by 5.7%,
and among men in urban areas there was a 9.2% reduction. The analysis,
which covered 15 European countries, took account of a large number
of factors which could have affected the results, including related
policies and enforcement such as minimum legal driving age, points-based
licensing and random checks.
22. There were reductions in deaths or injuries
among the population as a whole but this was not statistically
significant when other concurrent policies and infrastructure
quality were taken into account.
23. The lowering of the BAC limit from 0.08
to 0.05 also led to a significant reduction in fatal accidents
in Australia, specifically, an 18% reduction in Queensland and
8% reduction in New South Wales (Henstridge et al. 2004).
24. There is insufficient evidence to judge
what level of effect might be sustained by lowering the BAC limit,
although certain studies indicate that there could be positive,
long-term gains (Albalate 2006; Eisenberg 2003).
Public awareness and enforcement of BAC laws
There is sufficiently strong evidence to indicate
that publicity and visible, rapid enforcement is needed if BAC
laws are to be effective. Drivers need to be aware of—and
understand—the law. They also need to believe they are likely
to be detected and punished for breaking the law.
25. Sobriety checkpoints (ie random and
selective breath testing without the need for the police to have
grounds for suspecting drink-driving) can help reduce road traffic
injuries and deaths, according to two high-quality reviews (Peek-Asa
1999; Shults et al. 2001). In addition, random breath testing
(RBT) had an immediate, substantial and permanent impact on accidents
in three out of the four states studied in an Australian study
(Henstridge et al. 1997). A further study showed that sobriety
checkpoints in US states helped enforce the 0.08 law (Tippetts
et al. 2005).High quality review evidence also shows that mass-media
campaigns can reduce alcohol-impaired driving and alcohol-related
crashes (Elder et al. 2004).
BAC laws and changes in drink-driving behaviour
There is sufficiently strong evidence to indicate
that lowering the BAC limit changes the drink-driving behaviour
of drivers at all BAC levels.
The BAC law appears to act as a general deterrent
and the beneficial effects are not just restricted to the drivers
at the BAC levels involved.
26. Five studies (included in a systematic
review) showed that the introduction of a 0.08 BAC legal limit
reduced the number of alcohol-related deaths involving drivers
with a BAC of 0.10 or higher (Shults et al. 2001).
27. Another study showed that it had a differential
impact according to age, with the highest reductions in deaths
among younger drivers (14% reduction among 18-20 years, 9.7% among
21-24 years and 6.7% among those aged 25 and older) (Dee 2001).
28. Other studies have shown that reducing
BAC limits to 0.05 or lower has an impact on drivers who
drink heavily. For example, in 1991 when the BAC limit was lowered
from 0.08 to 0.05 in the Australian Capital Territory,
it reduced the incidence of drink-driving with a BAC well above
the original 0.08 limit (Brooks and Zaal 1993).
29. In addition, analysis of six roadside
surveys conducted between 1987 and 1997 in Adelaide, South Australia,
found that the percentage of people driving at night with a BAC
at or above 0.01, 0.05 and 0.08 decreased at an almost
uniform rate (Kloeden and McLean 1997).
30. Although these studies show reductions
in drink driving among those with high BAC levels, the precise
mechanisms that influence their willingness and capacity to change
their drink-driving behaviour are unclear.
31. A pan-European study reported that the
0.05 BAC limit had a statistically significant effect on
younger drivers, men, and men in urban areas (Albalate 2006).
Administrative licence suspension or revocation
There is sufficiently strong evidence from good
and high quality studies to show that administrative licence suspension
can help reduce road traffic injuries and deaths.
32. This effect pre-supposes that a BAC
limit is in place.
33. According to one study, such a policy
(which involves an immediate sanction) can reduce the likelihood
of being involved in a fatal, alcohol-related crash by 5%. It
affected drivers at all BAC levels. Laws mandating licence suspension
penalties after conviction had little effect, and did not appear
to be an effective deterrent (Wagenaar and Maldonado-Molina 2007).
34. Another study (Villaveces et al 2003)
showed that administrative licence revocation laws were associated
with a 5% reduction in overall mortality and a 5% reduction in
alcohol-related crash fatalities. A further study reported that
administrative licence revocation was associated with an 8.6%
and 10.6% reduction in alcohol-related fatal accidents (Kaplan
and Prato 2006).
35. A model of the effect of administrative
licence revocation legislation, taking into account variables
for the business cycle, mileage travelled and demographic characteristics,
also showed significant reductions in alcohol-related crash fatalities
(Freeman 2007). However, administrative licence revocation usually
has a BAC limit as a criterion, so the author says the results
should be "properly interpreted as a partial effect conditioned
on the existence of a BAC law".
Young drivers: zero tolerance laws and graduated
licensing schemes
There is sufficiently strong evidence to indicate
that zero tolerance laws and graduated licensing can help reduce
alcohol-related injuries and deaths.
36. Zero tolerance laws (where the legal
BAC limit is zero or close to zero for particular categories of
driver, such as young and probationary drivers) and graduated
licensing schemes (where young or novice drivers get more driving
privileges as they mature or their driving skills increase) can
help reduce alcohol-related injuries and deaths. One systematic
review reported a 9-24% reduction in crash fatalities, while another
reported reductions in the range of 11-33% (Shults et al. 2001;
Zwerling and Jones 2001).
37. Additional evidence is provided by primary
evaluation studies of high or good quality.
38. One study found that zero tolerance
laws, combined with administrative licence revocation, led to
a 4.5% reduction in fatal crashes among young drivers (Eisenberg
2003 ). Another showed that zero tolerance laws reduced the proportion
of deaths among underage drink-drivers by 24.4% (Voas et al 2003).
A further study linked zero tolerance laws to a 12% reduction
in alcohol-related fatalities and a 4% reduction in overall crash
fatalities (Villacaves et al. 2003).
39. Three US studies showed that zero tolerance
laws changed the pattern of alcohol consumption and the drink-driving
behaviour of young people overall ((Wagenaar et al Carpenter 2004
Liang and Huang 2008).
40. Good quality evidence shows that graduated
driver licensing restrictions help reduce crashes among young
drivers (Hartling et al.2004).
41. A study of the impact of graduated driver
licence restrictions on young drivers in New Zealand showed that
crashes involving those on a restricted licence were less likely
to have occurred at night—and less likely to have involved
passengers. In addition, the driver was less likely to have been
suspected of drinking alcohol, compared with crashes involving
a driver licensed under the old system (Begg et al 2001).
Modelling the impact of a 0.05 BAC limit
For the NICE review, a range of estimates were
produced for the number of alcohol-related driving casualties
that would be avoided in England and Wales from introducing a
0.05 BAC limit, according to different assumptions.
Assuming the policy produces the same relative
effect on the BAC distribution in the driver population of England
and Wales as observed in Australia, 144 deaths and 2929 injuries
were estimated to be avoidable.
Assuming the policy produces the same relative
effect on accidents as observed in other European countries, 77-168
deaths and 3611-15832 injuries were estimated to be avoidable.
42. A model was developed for NICE which
used the best evidence identified during the systematic review
to estimate what impact lowering the BAC limit to 0.05 would
have on the number of alcohol-related deaths and injuries in England
and Wales (ScHARR 2010).
43. A number of estimates were made, based
on an extrapolation of the effect of lowering the BAC limit
from 0.08 to 0.05 in other countries. The predictions also take
into account the ongoing shift in the distribution of BAC levels
in the driving population (that is, the amount that people are
drinking before driving). Given the many uncertainties related
to the data and the assumptions used in the modelling, the figures
should be interpreted with considerable caution.
44. There was limited evidence on the pattern
of drink-driving in the UK, as measured by BAC levels among the
driving population. There was also a lack of UK evidence on how
reducing the legal limit might change drink-driving behaviour
and the associated risk of casualties, particularly among those
drinking above the current 0.08 BAC limit. Consequently,
unknown parameters had to be calibrated or estimated from the
international literature.
INTERNATIONAL LESSONS
45. It is generally accepted internationally
that reducing the legal BAC driving limit is an effective drink-driving
deterrent and there is a clear trend, especially in Europe, towards
introducing a 0.05 limit.
46. Other interventions that are being introduced
to support this policy include lower BAC limits for young, learner,
probationary and professional drivers (ie zero tolerance laws),
and a range of enforcement measures, particularly random breath
testing but also alcohol ignition interlock devices and more consistent
and intensive enforcement in general.
47. European citizens (including drivers)
appear to support drink-driving policies already in force, as
well as proposals to extend them. The same is true of UK citizens.
However, UK citizens are less likely than other Europeans to know
what the legal BAC limit is, and are among the least likely to
have had their BAC level checked. In common with drivers in other
countries that do not permit random breath testing, UK drivers
are likely to think that they will never be checked.
48. The quality, comprehensiveness, and
reliability of data in international reviews of measures against
drink-driving are variable. Also, there is a lack of information
about contextual factors that might be important in explaining
differences in outcomes. General conclusions about the impact
of interventions may not be a reliable guide for policymakers
in any particular country.
August 2010
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54 NICE 2010 Review of effectiveness of laws limiting
blood alcohol concentration levels to reduce alcohol-related road
injuries and deaths. This was supported by the report: Modelling
the impact of a blood alcohol concentration limit of 50mg/100ml
in England and Wales (ScHARR 2010) Back
55
This review draws on a wide range of studies that used a variety
of units to define BAC levels-such as milligrams of alcohol per
100 millilitres of blood (50mg/100ml or 80mg/100ml). In this review
report we have not sought to standardise the terminology, but
in summary sections the shorthand of 0.05 or 0.08 is used. Back
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