Is body mass index a risk factor for motor vehicle driver injury? A cohort study with prospective and retrospective outcomes.
OBJECTIVE
To investigate the association between risk of motor vehicle driver injury and body mass index (BMI).


METHODS
In a cohort study of 10 525 New Zealand men and women, BMI was assessed in 1992-1993 (baseline), and data on deaths and hospitalizations for motor vehicle driver injury were obtained by record linkage to national health databases for the period 1988-1998. Hazard ratios (HR) and CI were estimated by Cox regression.


RESULTS
During a mean 10.3 years of follow-up, 139 fatal and non-fatal driver injury cases occurred (85 before baseline and 54 after). A U-shaped association was observed between driver injury risk and BMI, both crudely and after adjustment for covariates, which included age, sex, driving exposure, and alcohol intake (P-values for quadratic trend </=0.02). Participants in the highest (>/=28.7 kg/m(2); HR = 2.00, 95% CI: 1.18-3.39) and lowest (<23.5 kg/m(2); HR = 2.17, 95% CI: 1.27-3.73) quartiles of BMI were twice as likely to have experienced a driver injury during the follow-up period as participants in the reference quartile (25.9-28.6 kg/m(2); HR = 1.00).


CONCLUSIONS
Further research is needed to corroborate or refute the hypothesis that BMI is a risk factor for serious motor vehicle driver injury.
Whitlock
Gary
G
Clinical Trials Research Unit, University of Auckland, New Zealand. gary.whitlock@ctsu.ox.ac.uk
Norton
Robyn
R
Clark
Taane
T
Jackson
Rodney
R
MacMahon
Stephen
S
D000063:Accidents, Traffic / Q000401:mortality; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking; D015992:Body Mass Index; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D009765:Obesity / Q000150:complications* / Q000401:mortality; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors