We investigated the prevalence of social and medical factors that may increase the risk of MVAs among older patients aged ≥ 65 years. Notably, although less in number, 4 (3.1%) out of 127 participants were in a state of requiring level 1 or 2 assistance. By determining the current situation of older car drivers through this type of study, further measures can be improved at both national and medical field levels.
Previous literature has suggested that advanced age itself is a risk factor for MVAs.16 In addition, a wide variety of mental and physical dysfunctions inevitably observed during aging has been proven to yield a high incidence of MVAs.5 More specifically, dysfunctions in the sensory system (visual and auditory), central nervous system (stroke, depression, dementia, Parkinson’s disease, and insomnia), cardiovascular system (arterial hypertension, arrhythmia, coronary heart disease, and heart failure), musculoskeletal system (osteoarthritis and rheumatoid arthritis), diabetes mellitus, and polypharmacy as a consequence of the above potentially threatening traffic safety. Some of these factors are treatable, but most are refractory in older adults.
A causal association between multiple medications and MVAs in older people has already been demonstrated.17 In particular, use of narcotic analgesics combined with muscle relaxants, antidepressants, and antianxiety agents are known to lead to MVAs. Although trends in polypharmacy have recently been ameliorated in Japan,18 it remains a major problem among older adults. Dementia disturbs the integrated cognitive functions 19 and attention,20 which are vital for safe driving. However, dementia patients continue to drive in the community, without proper physical fitness and appropriate driving behavior.21 Frailty also increases the risk of MVAs.22 According to a Japanese observational study, pre-frailty/frailty individuals were highly at risk of experiencing MVAs in the past year compared with robust individuals (OR: 3.74, 95% CI: 1.75–7.96).23 However, a recent review article did not show the clear relationship between MVAs and sarcopenia.5 The prevalence of medical factors in the present study was as follows: polypharmacy, 27.6%; dementia, 16.4%; and frail, 15.0%, indicating that older adults with medical factors are driving on a daily basis.
No differences were observed in the medical factors between the everyday drivers and occasional drivers, except for the high frequency of sarcopenia among everyday drivers, which was contrary to our expectations. However, occasional drivers had a higher rate of MVA history (46%), while 58% of them were not intended to return their licenses, suggesting that occasional drivers may have a potential risk for MVAs in community.
A social opinion may be flipping in the restriction of car driving among older adults; however, the negative consequences should be considered. Recent cohort studies have suggested the relationship between driving cessation and an increased risk of functional deterioration in terms of physical, social, and mental health.24,25 With a limitation in out-of-home activity due to driving cessation, the alternative means of transportation are necessary for them to maintain their independence.26 In addition to social aging, the number of older people living independently in rural areas continues to increase. Thus, this would be particularly true for those living in rural areas, since car driving is indispensable in the absence of an adequate public transportation network. Therefore, the advantages of car driving among aged individuals should also be considered.
The present study has a strength, in that the data were collected through physical examinations performed by physicians; thus, the results are considered credible. However, this study has several limitations. First, considering the feasibility of the study, the finger-ring test and 30-second chair stand test were used to screen for sarcopenia, the Mini-Cog test for dementia, and the frailty screening index for frailty. However, the results of these screening tests should have been validated using more accurate scoring systems. Second, the data on the history of traffic accidents lacked detailed information, especially the time of occurrence and situation. Therefore, we cannot clearly describe its relationship with medical factors. Third, the generalizability needs to be carefully assessed, since the study included older patients visiting the hospitals. Despite these limitations, our attempt to identify the prevalence of medical factors among older drivers would be meaningful, as the results can objectively raise the potential issue in this aging society.
In summary, older people with medical factors drive cars on a daily basis in our community. To avoid MVAs caused by older drivers, further strict screenings and evaluations may be required; however, protecting the lives of older adults living in rural areas should be taken into account. Based on these findings, we hope to establish a process for renewing drivers’ licenses for older adults, in order to achieve social sustainability.