Factors Influencing Hospitalization Among Older Adults in Tokyo's Emergency Medical Services: The Role of Cerebral Disease and Seasonal Variations.
Geriatrics & gerontology international · 2025-10-22 · Registry study
Abstract
BACKGROUND: The global acceleration of population aging, especially in developed countries, has led to increased demands on emergency medical services. In Tokyo, Japan's largest city, over half of all emergency transports involve older adults aged 65 and older, a figure that continues to rise annually. These patients often present with complex medical conditions, require intensive prehospital interventions, and have higher hospitalization rates compared to younger populations. Despite these trends, there is a scarcity of studies examining the characteristics of older adults patients transported by ambulance and the factors associated with their hospitalization. METHODS: We conducted a retrospective study using emergency transport data from the Tokyo Fire Department (2017-2021), targeting patients aged 65 and older. We excluded non-transported cases, unknown severity assessments, and those deceased on initial evaluation. Patients were categorized into hospitalized (moderate to critical) and non-hospitalized (mild) groups. We analyzed demographics, accident type, location, prehospital care, and diagnosis. Logistic regression and inverse probability weighting were used to estimate risk differences (RDs) with 95% confidence intervals. RESULTS: This study analyzed 1.2 million older adults emergency transports in Tokyo, with 61% resulting in hospitalization. Hospitalized patients were older, more often male, and more frequently from care facilities. Cerebral diseases showed the highest risk difference for hospitalization (RD = 4.96), followed by cardiac and respiratory diseases. Cases with unspecified diagnoses accounted for 62% and were strongly associated with non-hospitalization (RD = 0.77). Severity profiles varied by disease, with moderate severity most common in cerebral cases and high severity in cardiac cases. Across all groups, emergency calls peaked between 9 and 10 a.m. CONCLUSION: This study identified disease-specific associations with hospitalization among older adults using emergency transport data in Tokyo. Even after adjustment, cerebral diseases remained strongly associated with hospitalization, while unspecified diagnoses were linked to non-hospitalization. These findings highlight the importance of prehospital assessment and may inform strategic improvements in triage and transport decision-making.