Release: September 9, 2001
Contact: Kenneth Satterfield(703) 519-1563[email protected]303-228-8460 (9/7-9/12)
STANFORD RESEARCHERS CONFIRM THE ASSOCIATION BETWEEN SLEEPINESS AND AUTO ACCIDENTS
More than 10,000 respond to an online survey.
Denver, CO -- Two years ago, a research study team led by Nelson Powell, MD, released his study, "A Comparative Model: Reaction Time Performance in Sleep Disordered Breathing Versus Alcohol Impaired Controls," at the American Academy of Otolaryngology--Head and Neck Surgery Annual Meeting. It stated that driving or engaging in safety-sensitive activities while sleepy might be as dangerous as driving under the influence of alcohol. Dr. Powell's research findings received extensive media coverage; many state transportation agencies incorporated his work into their driver education programs. (Refer to http://ipsapp006.lwwonline.com/servlet/GetFileServlet?J=2340&I=21&A=23&U=1&T=0)
Subsequently, Dr. Powell and "Dateline" NBC news joined together to conduct one of thelargest surveys on this topic to determine an association of sleepiness and sleep-disorders to motor vehicle accidents and injury. He returns to the 2001 annual meeting of the American Academy of Otolaryngology--Head and Neck Surgery to present the survey results.
The presentation was authored by Dr. Powell, Clinical Professor, Department of Psychiatry and Behavioral Science, Stanford University Medical School, and his fellow researchers Robert W. Riley, MD, Kasey Li, MD, and Christian Guilleminault, MD, all at Stanford, and Kenneth B. Schechtman, PhD, Associate Professor Biostatistics, Washington University School of Medicine, St. Louis, MO. Their conclusions, offered in "The Association of Risk, Accidents and Injury While Driving Sleepy," will be available to the nation's ear, nose, and throat specialists on September 10 at their annual meeting being held September 9-12, at the Colorado Convention Center in Denver, CO.
Methodology: This cross sectional survey evaluated 11,383 subjects who entered an NBC Dateline web site to take a 15 question quiz on sleepy driving titled "The National Driving Test" and who then took an expanded questionnaire (64 questions) on the same subject which included data on demographics (age, gender, race, marital status, income and educational levels). The survey followed the 15-question quiz on sleepy driving taken by 120,746 subjects on the same Dateline NBC web site.
The expanded questionnaire was designed at the Stanford Sleep and Research Center and the Division of Biostatistics at the Washington University School of Medicine in St. Louis. In an attempt to improve the ease of taking such a long questionnaire, all questions were designed to be short and clearly worded and as unambiguous as possible. The 64 questions collected details on demographics, driving habits, sleeping habits, work hours and schedules, sleepiness, alcohol, accidents and injury data. The quiz and questionnaire were presented one week prior to an hour-long Dateline NBC television program on sleepy driving. Only those who had completed the quiz were offered the opportunity to take the expanded questionnaire. An Epworth Sleepiness Scale (ESS) was included in the body of the questionnaire to assess sleepiness levels against other outcome metrics.
Results: A total of 120,746 people entered the Dateline NBC web site and completed the 15-item questionnaire that was directly associated with Dateline's television program on sleepy drivers. Nine percent of this large sample, a subset that included 11,383 subjects, to the linked web site to the expanded questionnaire. The latter is the source of data for the findings below. Because 513 of these individuals did not complete the expanded questionnaire or indicated that they do not drive, this report is based on a sample of 10,870 drivers who completed the questionnaire. Demographic data indicates that participants were 61% women, middle aged, overwhelmingly Caucasian, well educated and married.
During a three-year period, 2,351 subjects reported that they had at least one accident during the study period. Almost nobody (0.2 percent) admitted to being cited for drunk driving during the past year, and most subjects (86.7 percent) did less than 15 percent of their driving between midnight and six a.m. Twenty-two and one half percent of the respondents reported having one of three sleep disorders: sleep apnea, insomnia, or narcolepsy. Other survey results indicated that:
* Younger age was significantly associated with an increased number of accidents. Subjects who reported three or more accidents were more than nine years younger than those who reported no accidents. There was also a strong association between increased accident rates and being African American or Hispanic, having limited education or minimum income, and being unmarried.
* An association existed between motor vehicle accidents and driving characteristics, the participant's work schedule, and two indicators of alcohol use. In all cases, results were significant, with increased probability for accidents of drivers with evening, night, or irregular work schedules, and those reporting a previous citation for drunk driving.
* The Epworth sleepiness score (a short series of questions that query the likelihood of sleepiness) of participants who reported three or more accidents was 3.4 times greater than the score of those who reported no accidents. The difference between the amount of reported sleep before work days and the amount reported when the subject was not working the next day was 0.50 hours greater in those with multiple accidents.
* A multivariate analysis of independent predictors listed the main findings of this study and included the ESS, driving at night, and consulted a professional because of tiredness, which helped to further associate and implicate sleepiness as a factor associated with increased accidents. The data suggest a strong tendency for repeat accidents associated with sleepiness that cannot be passed off as just "a run of bad luck." The fact that there was a statistically significant change in sleeping patterns (hours of sleep) associated with increased accidents supports a sleepiness and accident association.
* In those subjects with sleep disorders there was a statistically significant higher prevalence for three or more accidents. In addition, several factors associated with sleepiness and an increase in accidents carried similar risks as factors found in drinking drivers and accidents.
This study was somewhat different than other surveys since it included a large sample size, direct entry data via an Internet link and immediate and direct downloading of the data to a SAS statistical program. The authors acknowledge certain study limitations. For instance, it was not a true sample of the general population since the sample was self-selected. Additionally, subjects needed Internet access and a basic knowledge of its use. This group also must have been exposed to one of the media announcements on sleepy drivers, either on TV or in the written press, in order to be directed to the web site. Hence, it is probable this group had a special or personal interest in sleepiness and the effects of driving sleepy.
Conclusion: This cross-sectional survey contains a detailed statistics and results section that demonstrates associations of self reported sleepiness and sleep disorders with accidents and injuries in a large sample of drivers. The authors do not imply that these study data outcomes clearly delineate the accident or injury cause-effect relationship. However, it does implicate and lends supportive evidence that progressive levels of sleepiness are a factor that may contribute to an increase in auto accident and injury rates.
- end -
RSS