# In-Depth Evaluation of Association between Crash and Hand Arthritis via Naturalistic Driving Study
## 1 Introduction  
Rheumatoid arthritis is a health condition that is characterized by the inflammation of joints that can limit an individual's range of motion. In the United States, approximately 54 million individuals are diagnosed with arthritis, and among them, 24 million had activity limitations attributable to the condition [1]. Arthritis typically develops with age, and approximately 50% of individuals over the age of 65 have been diagnosed with arthritis [1]. Severe arthritis may increase the driver's crash risk due to a reduced range of joint motion and pain. The high prevalence of arthritis among the driver population is a safety and public health concern, especially among senior drivers. There is a need to understand the impacts of arthritis on crash risk and driving behavior because this understanding will provide critical information for the development of assistance systems that improve the safety and mobility of drivers with arthritis. Scholars have shown that individuals with rheumatoid arthritis could have deteriorated driving performance and difficulty in driving [2, 3]. [PERSON] et al. [4] indicated that drivers with rheumatoid arthritis and osteoarthritis had difficulty conducting common driving tasks, including buckling the seat belt, looking over one's shoulder to check blind spots, turning the wheel, and using the hand brake. Similarly, [PERSON] et al. [5] showed that drivers with arthritis experienced problems that could affect safety. However, the authors of these studies also suggest that the majority of the difficulties with the driving task would not necessarily affect safety. Proper techniques, such as threading steering and backing up using mirrors can effectively mitigate the impairment associated with arthritis [4]. Relatively few studies have directly linked arthritis with crash risk, and inconsistent results have been reported. [PERSON] et al. (2016) conducted a population-based case-control study of chronic medical conditions and crashes among older drivers. The study found that arthritis was associated with an increased risk among females (odds ratio [OR] = 1.8) but not among males (OR = 0.8). A 5-year cohort study (1991-1995) by [PERSON] et al. (2017) based on police-reported crashes in Alabama for 174 senior drivers (>55 years old) revealed that there is no association between arthritis and crashes. Similarly, in a cohort study of 1791 older drivers, [PERSON] et al. (2018) found no association between arthritis and crash involvement. The inconsistency in the relevant literature suggests that in-depth studies are needed to fully understand the safety impacts of arthritis. Fitness-to-drive has been a major safety and mobility concern for senior drivers, and it can be directly affected by arthritis (2019). Researchers have shown that the fitness abilities of senior drivers can affect both driving safety and the decision to give up driving. [PERSON] et al. (2019) showed that fitness-to-drive is a key reason that seniors give up driving. Using naturalistic driving study (NDS) data, [PERSON] et al. (2018) showed that certain fitness measures, including upper body strength, are associated with increased crash risk. Because drivers with arthritis or other fitness conditions tend to drive less than others, arthritis could be a factor underlying the well-documented low-mileage-bias (LMB) issue for senior drivers. The LMB refers to the phenomenon that senior drivers with lower annualized mileage are at significantly higher risk compared to drivers with higher annualized mileage (2019). The connection between arthritis and these known risk factors can help shed light on the causal path for arthritis and crashes. Arthritis can also affect driver behavior, such as cellphone use and other secondary tasks.