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Use of caffeinated substances and risk of crashes in long distance drivers of commercial vehicles: case-control study

BMJ 2013; 346 doi: (Published 19 March 2013) Cite this as: BMJ 2013;346:f1140
  1. Lisa N Sharwood, research scholar1,
  2. Jane Elkington, project manager1,
  3. Lynn Meuleners, director2,
  4. Rebecca Ivers, injury division director1,
  5. Soufiane Boufous, senior research fellow13,
  6. Mark Stevenson, director4
  1. 1George Institute for Global Health, PO Box M201, NSW 2050, Australia
  2. 2Curtin-Monash Accident Research Centre, WA 6845, Australia
  3. 3Transport and Road Safety (TARS) Research, University of New South Wales, NSW, Australia
  4. 4Monash University Accident Research Centre, Monash Injury Research Institute, VIC 3800, Australia
  1. Correspondence to: L N Sharwood, 98 Bunnerong Rd, Pagewood, NSW 2035 Australia lsharwood{at}
  • Accepted 5 February 2013


Objective To determine whether there is an association between use of substances that contain caffeine and the risk of crash in long distance commercial vehicle drivers.

Design Case-control study.

Setting New South Wales (NSW) and Western Australia (WA), Australia.

Participants 530 long distance drivers of commercial vehicles who were recently involved in a crash attended by police (cases) and 517 control drivers who had not had a crash while driving a commercial vehicle in the past 12 months.

Main outcome measure The likelihood of a crash associated with the use of substances containing caffeine after adjustment for factors including age, health disorders, sleep patterns, and symptoms of sleep disorders as well as exposures such as kilometres driven, hours slept, breaks taken, and night driving schedules.

Results Forty three percent of drivers reported consuming substances containing caffeine, such as tea, coffee, caffeine tablets, or energy drinks for the express purpose of staying awake. Only 3% reported using illegal stimulants such as amphetamine (“speed”); 3,4 methylenedioxymethamphetamine (ecstasy); and cocaine. After adjustment for potential confounders, drivers who consumed caffeinated substances for this purpose had a 63% reduced likelihood of crashing (odds ratio 0.37, 95% confidence interval 0.27 to 0.50) compared with drivers who did not take caffeinated substances.

Conclusions Caffeinated substances are associated with a reduced risk of crashing for long distance commercial motor vehicle drivers. While comprehensive mandated strategies for fatigue management remain a priority, the use of caffeinated substances could be a useful adjunct strategy in the maintenance of alertness while driving.


  • Contributions: LNS contributed to the design of data collection tools, collected data for the whole study, trained associate staff who collected data, wrote the statistical analysis plan, cleaned and analysed the data, and drafted and revised the paper. JE contributed to the design of data collection tools, trained associate staff, managed the project, and revised the paper. LM and RI contributed to protocol design, data collection tool design, analysis and interpretation of data, and revision of the paper. SB assisted in writing the statistical analysis plan and with the analysis and interpretation of data, and the revision of the paper. MS was principal investigator and conceived the protocol, guided data collection tool development, analysis and interpretation of data, and revision of the paper as doctoral supervisor of LNS. LNS is guarantor.

  • Funding: The study was funded by the Australian Research Council, the Australian Government Department of Infrastructure, Transport, Regional Development and Local Government, DiagnoseIT, the National Transport Commission, Queensland Transport, the Roads and Traffic Authority of New South Wales and Main Roads in Western Australia. LNS is supported by Australian postgraduate awards industry grant (Australian Research Council). MS and RI are supported by NHMRC fellowships.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the human research and ethics committees at the University of Sydney, NSW (No 10294) and Curtin University, WA, and informed consent was given by all participants.

  • Data sharing: No additional data available.

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