Relative risk of head injury

Cycle helmets are often promoted on the presumption that cyclists are especially likely to suffer head injuries. The data below shows that cyclists are only a very small part of the head injury burden and that other people are much more likely to be head injury victims.

Ontario, Canada

Major head injuries per year	2,494	100%
of which:
Motor vehicle involvement, including pedestrians but excluding cyclists		49%
Falls		35%
Homicide		6%
Suicide		2%
Other causes		6%
Cyclists		less than 2%

Source: CIHI, 2004

Canada (whole country)

All head injuries 2003 - 2004	16,800	100%
Falls		45%
Motor vehicle involvement (excl cyclists)		36%
Assault		9%
Other causes		10%
Cyclists		5%

Source: CIHI, 2006

As the proportion of major head injuries that are cyclists is lower than the proportion of all head injuries (although the populations differ), it would appear that on average head injuries to cyclists are less severe than those to other groups.

US traumatic brain injury deaths per year

The following table shows the average number of deaths per year over the period 1997 to 2007.

Activity	Average TBI fatalities/year	% of total
All causes	53014	100%
Motorists	7955	15%
Pedestrians	1825	3.4%
Motorcyclists	1361	2.6%
Cyclists	325	0.6%

Source: Coronado et al, 2011

The source data also shows that only 44.5% of US bicyclist fatalities involve head injuries (325/730).

References

CIHI, 2004

Major Head and Spinal Cord Injury Hospitalizations in Ontario, 2001-2002. Canadian Institute for Health Information. Ontario Trauma Registry Analytic Bulletin, March 2004.

CIHI, 2006

Head Injuries in Canada: A Decade of Change (1994-1995 to 2003-2004) . Canadian Institute for Health Information, August 2006.

Coronado et al, 2011

Coronado VG, Xu L, Basavaraju SV, McGuire LC, Wald MM, Faul MD, Guzman BR, Hemphill JD, 2011. Surveillance for Traumatic Brain Injury Related Deaths: United States, 1997- 2007. Centers for Disease Control and Prevention May 6, 2011 / 60(SS05);1-32.