Year of Publication

2017

College

Public Health

Degree Name

Master of Public Health (M.P.H.)

Committee Chair

David M. Mannino, MD

Committee Member

Susan E. Spengler, MD, MSPH

Committee Member

Timothy S. Prince, MD, MSPH

Committee Member

Isabel Mellon, PhD

Abstract

OBJECTIVE: The Federal Motor Carrier Safety Administration (FMCSA) developed a National Registry of Certified Medical Examiners (NRCME) as a stride toward greater driver safety and public health. This retrospective, observational, cross-section study is intended to trend and analyze driver related factors that are pertinent to FMCSA certifying medical examination performed by NRCME providers in addition to driver behaviors and environmental factors from the years 2009 to 2015. The results of this study are intended to speculate the effectiveness of the NRCME and propose additional public health interventions aimed to reduce large vehicle fatalities.

METHODS: Data was extracted from the Fatality Analysis Reporting System (FARS) of the National Highway Traffic Safety Administration (NHTSA). For each year from 2009 to 2015, data outputs were restricted to vehicles weighing over 10,000 lbs. The fields that were queried included: crash fields, vehicle fields, occupant fields, and driver fields. Within those fields, the outputs of interest were: speeding, crash hour, crash month, light condition, atmospheric condition, age, injury severity of the driver, extent of vehicle damage, commercial driver license (CDL) status, compliance with CDL restrictions, driver related factor regarding the use or failure to use medication/drugs, condition or impairment of the driver at the time of the crash (fatigue or illness related), the use of restraints, and whether an airbag had deployed. Data was analyzed for associations between the outputs of interest and year, driver injury severity, and vehicular damage using Pearson Chi-Square, Kruskal-Wallis H, and Mann-Whitney U tests. ANOVA was used to assess difference in drivers’ mean age among years 2009-2015, driver injury severity levels, and vehicular damage. Pearson Chi-Square was used to determine an association between fatigue and daylight. Cross tabulations were used to look for proportional trends found among or between independent and dependent variables with statistically significant associations. Spearman rho was used to determine whether there was a linear relationship between daylight and fatigue. It was also used to assess the linear relationship between injury severity and vehicular damage.

RESULTS: The fatality rate was highest at 147.229 fatal large vehicle crashes per billion vehicle miles in 2015. The mean age of the drivers was not significantly different from 2009-2015. The mean driver age was highest for those who sustained fatal injury (48.66 years, F= 2.232, p < .001). From 2009 to 2015, the proportion of fatal accidents reported to involve speeding, fatigue, illness, and failed use of restraints had no statistically significant change over those years. Over those same years, the proportion of fatal crashes with reportedly fatigued divers ranged from 1.2-1.8%, those ill ranged from 0.4-0.6%, those speeding ranged from 21.7-23.4% and those with failed restraint use ranged from 15.7-17.5%. Drivers’ misuse of medication or drugs were reported in only 3 cases in this study, revealing a significant reporting deficiency. Statistically significant associations, with greater than expected counts, were observed between fatal injury and: speeding, failed restraint use, driver fatigue, driver illness, invalid CDL status, and lighting conditions other than daylight (p = .025, p < .001, p < .001, p < .001, p < .001, p < .001, p < .001, respectively). Disabling damage had statistically significant associations with weather that was not clear, driver fatigue, driver illness, and invalid CDL (p < .001, p < .001, p < .001, p = .004, respectfully). A very weak linear relationship was found between lighting and fatigue (rho = .057, p < .001). A moderate linear relationship was present between driver injury severity and vehicular damage (rho = 0.422, p < .001).

CONCLUSIONS: Though likely underreported and underestimated, the proportion of fatal large vehicle crashes in relation to driver fatigue, medication misuse, and driver illness or blackout was minute. Whereas the proportion related to speeding and failed use of restraints was substantial. The FMCSA certifying medical examination is an intervention to ensure safe driving by preventing and restricting drivers with potentially incapacitating medical conditions. This study highlights the importance of addressing safety behaviors in addition to illness and fatigue. Adding a query about safety restraints and speeding to the FMCSA certified medical examination report form is an opportunity to provide a nationalized message of safety to commercial drivers, further promoting a culture of safety.

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