239 Mortality of Motor Vehicle Accidents by Elderly Drivers: A Nationwide Hospital-Based Registry in Japan

Abstract

Japan is the leading aging country, and motor vehicle accidents (MVAs) by elderly drivers have been exceedingly increasing in recent years. However, there were no clinical studies evaluating the impact of MVAs by elderly drivers in Japan. We aimed to assess the MVA incidence and outcomes by elderly drivers, especially by those aged >=75 years who were transported to emergency department and registered in the Japan Trauma Data Bank. This was a prospective nationwide hospital-based registry for trauma patients from 256 institutions in Japan, and enrolled all MVA drivers having more than legal age for driving between 2004 and 2015. We divided the registered patients into the following three groups; the adult (aged =<64 years), the young-old (aged 65-74 years), and the old-old (aged >=75 years). The primary outcome was in-hospital mortality, and the secondary outcome was length of hospital stay (LOS) and discharge place. The trend in the proportion of MVAs caused by the young-old or the old-old group was evaluated using the Cochran-Armitage trend test. To assess the association of the old-old group with in-hospital mortality compared to the adult group, we applied a multivariable logistic regression analysis. During the study period, a total of 236,698 trauma patients were registered, and 39,691 patients were eligible for our analysis. The proportion of MVAs caused by the young-old and the old-old group significantly increased from 8.1% and 3.6% in 2004 to 10.6% and 13.2% in 2015, respectively (each P for trend<0.001). As for the primary outcome, unadjusted in-hospital mortality rate increased with age, but the mortality rate decreased year by year irrespective of age group. In the multivariable logistic regression analysis, in-hospital mortality rate was significantly higher in the old-old group than in the adult group (17.3% [584/3372] versus 8.0% [2556/31,985], adjusted odds ratio 4.80; 95% confidence interval 4.06-5.67). In addition, among survival cases, LOS was longer in the old-old group than in the adult group (median [interquartile range], 19 [8-41] versus 13 [4-31], p<0.001), and the old-old group was more likely to discharge to health care facilities such as nursing home or long-term care institutions than the adult group (46.9% [1580/3372] versus 33.0% [10,553/31,985], p<0.001). In the super-aging society of Japan, the proportion of MVAs by elderly drivers increased year by year, and the mortality rate was highest in the old-old group. We should pay further attention to the trend in the MVA incidence and outcomes by elderly drivers, especially the old-old group, to decrease the MVA mortality in Japan.View Large Image Figure ViewerDownload Hi-res image Download (PPT)