1997 NEJM-ASSOCIATION BETWEEN CELLULAR-TELEPHONE CALLS AND MOTOR VEHICLE COLLISIONS

Background
Because of a belief that the use of
cellular telephones while driving may cause collisions,
several countries have restricted their use in
motor vehicles, and others are considering such
regulations. We used an epidemiologic method, the
case–crossover design, to study whether using a cellular
telephone while driving increases the risk of a
motor vehicle collision.
Methods
We studied 699 drivers who had cellular
telephones and who were involved in motor vehicle
collisions resulting in substantial property damage
but no personal injury. Each person’s cellular-telephone
calls on the day of the collision and during
the previous week were analyzed through the use of
detailed billing records.
Results
A total of 26,798 cellular-telephone calls
were made during the 14-month study period. The
risk of a collision when using a cellular telephone
was four times higher than the risk when a cellular
telephone was not being used (relative risk, 4.3; 95
percent confidence interval, 3.0 to 6.5). The relative
risk was similar for drivers who differed in personal
characteristics such as age and driving experience;
calls close to the time of the collision were particularly
hazardous (relative risk, 4.8 for calls placed
within 5 minutes of the collision, as compared with
1.3 for calls placed more than 15 minutes before the
collision; P0.001); and units that allowed the hands
to be free (relative risk, 5.9) offered no safety advantage
over hand-held units (relative risk, 3.9; P not significant).
Thirty-nine percent of the drivers called
emergency services after the collision, suggesting
that having a cellular telephone may have had advantages
in the aftermath of an event.
Conclusions
The use of cellular telephones in motor
vehicles is associated with a quadrupling of the
risk of a collision during the brief period of a call.
Decisions about regulation of such telephones, however,
need to take into account the benefits of the
technology and the role of individual responsibility