Objective: To study the global distribution of risk factors, causes and 3-month mortality of young ischemic stroke patients, by performing a patient data meta-analysis form different cohorts worldwide.

Methods: We did a pooled analysis of individual patient data from cohort studies which included consecutive ischemic stroke patients aged 18-50 years. We studied differences in prevalence of risk factors and causes between different ethnic groups, geographic regions and countries with different income levels. We investigated differences in 3-month mortality by mixed-effects multivariable logistic regression.

Results: We included 17,663 patients from  32 cohorts in 29 countries. Hypertension and diabetes were most prevalent in Blacks (hypertension, 52.1%; diabetes, 20.7%) and Asians (hypertension 46.1%, diabetes, 20.9%). Large vessel atherosclerosis and small vessel disease were more often cause of stroke in high-income countries (HICs; both p<0.001), whereas ‘’other determined stroke’’ and ‘’undetermined stroke’’ were higher in low and middle-income countries (LMICs; both p<0.001). Patients in LMICs were younger, had less vascular risk factors, and despite this, more often died within 3 months than those from HICs (OR 2.49; 95% CI 1.42-4.36).

Conclusion: The ethnic and regional differences in risk factors and causes of stroke at young age provide an understanding of ethnic and regional differences in incidence of ischemic stroke. Our results also visualize the dissimilarities in outcome after stroke in young adults that exist between LMICs and HICs, which should serve as a call to action to improve healthcare facilities in LMICs.