First ischemic stroke in young adults: Sex and age-related differences in stroke rates, risk factors, and etiologies

Abstract

Introduction: Sex differences in stroke incidence, vascular risk factors (VRFs), and etiologies among young adults remain underexplored, particularly regarding age-related patterns.

Patients and methods: We retrospectively analyzed young adults (18-55 years) with first-ever ischemic stroke treated at certified acute stroke units/centers between 2014 and 2022, using Swiss Stroke Registry data. Stroke rates (per 100,000 person-years), VRFs, and etiologies were assessed by age and sex.

Results: Among 3,995 stroke patients, stroke rates were similar between sexes until age 35, after which men showed a more pronounced exponential increase. This rise was particularly notable in patients with elevated BMI and ⩾2 VRFs. The proportion of patients with ⩾2 VRFs rose with age (18-35: 22%; 36-50: 48%; 51-55: 63%). While no statistically significant differences in VRF profiles were observed between men and women aged 18-35, men accumulated VRFs about five years earlier than women, leading to a higher prevalence of multiple VRFs in men aged 36-50, with the gap narrowing in the 51-55 group. Stroke etiologies shifted with age: patent foramen ovale and cervical artery dissection predominated in younger patients, while large artery atherosclerosis, small vessel disease, and strokes of undetermined etiology increased with age, with notable sex differences.

Discussion and conclusions: This study highlights sex and age differences in ischemic stroke rates, VRFs, and etiologies among adults under 55 years. After 35, stroke rates rose more sharply in men, paralleling their higher VRF burden. These findings emphasize the importance of early management of VRFs-including overweight-to mitigate stroke risk.

Keywords: Acute stroke; etiology; risk factors; sex differences.

Graphical abstract

Figure 1.

Patient flow chart. AF: atrial fibrillation. ESUS: embolic stroke of unknown source. LEF: low ejection fraction. mRS: modified Rankin Scale. PFO: patent foramen ovale. MPV: mechanical prosthetic valve. SVD: small vessel disease. TIA: transient ischemic attack.

Figure 2.

Age- and Sex-specific occurrence rates of first-ever ischemic stroke in Switzerland (2014-2022). Stroke rates per 100,000 person-years, stratified by sex and age (a), presence of ⩾ 2 vascular risk factors (VRFs) (b), BMI ⩾ 25 (c), and etiology (d). Data points represent observed rates; solid lines are fitted rates from Quasi-Poisson regression models adjusting for age, sex, their interactions, and additional interactions with etiology, number of risk factors, and BMI (Supplemental Tables 1–4).

Figure 3.

Vascular risk factors across age groups and sex: (a) percentage distribution of hypertension, hyperlipidemia, diabetes, smoking, and obesity across different age groups for both sexes and (b) Boxplot distribution of the number of cardiovascular risk factors by age group and sex.

Figure 4.

Distribution of Stroke Etiologies across age groups and sex. Percentage distribution of stroke etiologies across age groups (a) and in age groups 18–45 and 46–55 and segmented by sex (b).