How does number of risk factors affect prognosis in young patients with ischemic stroke?

We aimed to explore clinical features of young patients with ischemic stroke with no traditional vascular risk factors and to assess the impact of risk factor counts on outcomes. We included 990 patients aged 15 to 49 years with first-ever ischemic stroke followed for a mean of 9.0 ± 3.8 years (survivors). Risk factors were categorized as well-documented and less well-documented. Outcome measures were unfavorable functional outcome (3-month modified Rankin Scale 2-6); recurrent ischemic stroke; myocardial infarction or other arterial noncerebrovascular event; and death from any cause. Compared with those with at least 1 well-documented risk factor, the 127 (12.8%) patients without risk factors were younger (median age, 37 versus 44 years; P<0.001), likely to be females (54.3% versus 34.9%; P<0.001), and they had more frequently a low-risk source of cardioembolism (21.3% versus 8.1%; P<0.001), internal carotid artery dissection (12.6% versus 6.4%; P=0.011), or vertebral artery dissection (17.3% versus 7.2%; P<0.001). The groups had similar 3-month functional outcomes. Patients without well-documented risk factors had less frequently recurrent ischemic strokes (4.7% versus 13.6%; log rank P=0.014), noncerebrovascular arterial events (0% versus 6.1%; P=0.008), and lower long-term mortality (3.4% versus 14.3%; P=0.003) than did those with at least 1 risk factor. Adjusted for demographics and stroke etiology, the number of well-documented risk factors was associated with higher risk for noncerebrovascular events. Increasing count of less well-documented risk factors was, in turn, independently associated with higher long-term mortality. In young adults with first-ever ischemic stroke, risk factor counts added independent prognostic information regarding noncerebrovascular events and mortality.