Association Between Young-Onset Dementia and Risk of Hospitalization for Motor Vehicle Crash Injury in Taiwan.

Importance: Several studies have suggested that older-onset dementia is associated with an increased risk of motor vehicle crash injury (MVCI). However, evidence of an association between young-onset dementia and the risk of MVCI is insufficient, particularly in Asia. Objective: To investigate the association between young-onset dementia and MVCI-related hospitalization in Taiwan. Design, Setting, and Participants: In this nationwide, population-based cohort study in Taiwan, a cohort of 39 344 patients aged 40 to 64 years with incident dementia diagnosed between 2006 and 2012 was matched 1:1 with a cohort of participants without dementia by age, sex, and index year (initial diagnosis of dementia). Participants were identified from Taiwan's National Health Insurance Research Database (NHIRD). Data were analyzed between March 25 and October 22, 2021. Exposures: Dementia, defined by International Classification of Diseases, Ninth Revision, Clinical Modification codes. Main Outcomes and Measures: Hospitalization for MVCI, determined using linked data from Taiwan's Police-Reported Traffic Accident Registry and the NHIRD from January 1, 2003, to December 31, 2015. Hazard ratios (HRs) for MVCI-related hospitalization were estimated using Cox proportional hazards regression models adjusted for sex, age, salary-based insurance premium, urbanization level, and comorbidities. Results: Of the 78 688 participants, 47 034 (59.8%) were male; the mean (SD) age was 54.5 (7.4) years. During the 10-year follow-up period, the incidence density of MVCI-related hospitalization was 45.58 per 10 000 person-years (95% CI, 42.77-48.39 per 10 000 person-years) among participants with dementia and 24.10 per 10 000 person-years (95% CI, 22.22-25.99 per 10 000 person-years) among participants without dementia. Compared with participants without dementia, patients with young-onset dementia were at higher risk of MVCI-related hospitalization (adjusted HR [aHR], 1.83; 95% CI, 1.63-2.06), especially those in younger age groups (aged 40-44 years: aHR, 3.54; 95% CI, 2.48-5.07) and within a shorter period (within 1 year of follow-up: aHR, 3.53; 95% CI, 2.50-4.98) after dementia was diagnosed. Patients with young-onset dementia also had a higher risk of being a pedestrian when the crash occurred (aHR, 2.89; 95% CI, 2.04-4.11), having an intracranial or internal injury (aHR, 2.44; 95% CI, 2.02-2.94), and having a severe injury (aHR, 2.90; 95% CI, 2.16-3.89). Conclusions and Relevance: In this retrospective cohort study, patients in Taiwan with a diagnosis of young-onset dementia had a higher risk of MVCI-related hospitalization than did individuals without dementia and the risk varied by age, disease duration, transport mode, injury type, and injury severity. These findings suggest a need for the planning of strategies to prevent transportation crashes among patients with young-onset dementia.