Aim
Urbanization and ageing are worldwide issues for healthcare providers. In particular, older adults aged 90 years and older have increased cognitive impairment and lower daily functioning than younger adults. However, the healthcare use of the oldest old remains unclear. This study aimed to describe the healthcare use of the oldest old compared with younger older adults in a city using the ecology of medical care model.

Methods
We conducted a cross-sectional study. This study targeted all residents aged 75 years and older registered in a city in Japan for one year. We described healthcare use per 1000 inhabitants over a 1-month period and included: outpatient visits, emergency department visits, hospitalizations, home visits, home care services, and facility services. We also compared healthcare use among older adults aged 75–89 years and 90 years and older.

Results
We described the healthcare use of 454 366 (male/female: 186 177/268 189) older adults. The numbers of persons per 1000 residents who used healthcare resources at least once in 1 month (75–89 years/90 years and older) were: outpatient clinic visits, 622/570; hospital outpatient visits, 300/263; advanced treatment hospital outpatient visits, 16/6; emergency department visits, 10/27; hospitalizations, 45/96; advanced treatment hospital hospitalizations, 2/1; planned home visits, 36/228; urgent home visits, 6/38; home care services, 173/533; and facility services, 32/178.

Conclusions
The results revealed that older adults over 90 years had more hospitalizations, emergency department visits and home visits, and used facility/home care services more compared with older adults aged 75–89 years. The results provide a useful benchmark for healthcare use estimation. Geriatr Gerontol Int 2022; 22: 483–489.