Background:
An emerging trend of increasing strokes has been noted among the younger population. However, studies on the age differences in incidence and in-hospital outcomes are lacking, particularly for the Asian population.

Objective:
To compare incidence and in-hospital outcomes and to evaluate their 10-year trends according to age and stroke subtype.

Method:
A total of 137,927 patients with a primary diagnosis of stroke or transient ischemic attack (TIA) in Hong Kong between 2011-2020 were included. Outcomes were incidence, in-hospital deaths, length of stay (LOS), and 30-day unplanned readmission rates by age and subtype. Time-series analysis using cumulative annual percentage changes (CAPC) and statistical process control (SPC) was conducted to examine time trends.

Results:
Decreasing incidence was observed in all subtypes among old adults (aged≥65), who yielded the most dramatic incidence reduction in ischemic stroke (IS) and intracerebral hemorrhage (ICH) (per 100,000 person-years 2011-2020, CAPC; IS: 931 to 424, -54%; ICH: 180 to 101, -44%), compared to young (aged≤44) and midlife adults (aged 45-64). TIA incidence increased in young by 19% but declined by 40% in old adults, whereas subarachnoid hemorrhage (SAH) incidence remained steady for young and midlife. In-hospital deaths (10%) and 30-day unplanned readmission rates (9.8%) were highest for old adults with any subtype, while acute LOS was longest in the young (mean [SD] days; IS: 6.1 [13.3]; ICH: 14.6 [47.4]; SAH: 21.9 [60.2]) except TIA. SPC analysis demonstrated a significant rise in in-hospital deaths for all IS. There were longer LOS and more 30-day stroke-cause unplanned readmissions for all subtypes in young adults over ten years, but outcomes did not change in old adults apart from IS and TIA.

Conclusion:
Age-specific trends in incidence and in-hospital outcomes varied in stroke subtypes. The temporal increase in LOS and readmissions in young strokes highlight the need for age-targeted care improvements.