Silent cerebrovascular disease increases risk for subsequent stroke

In patients aged 50 years and older, silent brain infarction and white matter disease were common and correlated with significant increases in risk for subsequent symptomatic stroke, according to a study published in Neurology.

“In previous work, we developed a Natural Language Processing (NLP) algorithm to identify individuals with incidentally-discovered [silent brain infarction (SBI)] and [white matter disease (WMD)] through the automated review of neuroradiology reports obtained in clinical practice and demonstrated both a high degree of accuracy with respect both to the findings on neuroimaging reports and also to the findings on the actual neuroimages when these are re-read,” David M Kent, MD, MS, from the Predictive Analytics and Comparative Effectiveness Center at Tufts Medical Center in Boston, and colleagues wrote. “Herein, we port the algorithms into a large integrated health care system in southern California to examine the prognostic significance of NLP-identified, incidentally discovered silent cerebrovascular disease with respect to the future risk of stroke.”

The study comprised 262,875 patients from the Kaiser Permanente South California health system who were aged at least 50 years and had silent cerebrovascular disease without prior ischemic stroke, transient ischemic attack or dementia/Alzheimer’s disease. Patients received a head CT or MRI between 2009-2019. Natural language processing from neuroimaging reports aided in the identification of silent brain infarction (n = 13,154) and white matter disease (n = 78,330).

Study data showed that for patients with silent brain infarction, incidence of future stroke was 32.5 (95% CI, 31.1-33.9) per 1,000 patient-years, 19.3 (95% CI, 18.9-19.8) per 1,000 patient-years for patients with white matter disease and 6.8 (95% CI, 6.7-7) per 1,000 patient-years for patients without silent cerebrovascular disease. Among those with both white matter disease and silent brain infarction, the researchers reported an incidence rate of 40.6 (95% CI, 38.4-42.9).

According to Kent and colleagues, the crude hazard ratio correlated with silent brain infarction was 3.4 (95% CI, 3.25-3.56) and 2.63 (95% CI, 2.54-2.71) for white matter disease. The adjusted HR with MRI-discovered silent brain infarction was 2.95 (95% CI, 2.53-3.44) for those younger than 65 years and 2.15 (95% CI, 1.91-2.41) for those older than 65 years. For those younger than 65 years, the adjusted HR with CT scan was 2.48 (95% CI, 2.19-2.81) and 1.81 (95% CI, 1.71-1.91) for those older than 65 years. Kent and colleagues noted that the adjusted HR correlated with a finding of white matter disease was 1.76 (95% CI, 1.69-1.82); however, it was not modified by age or imaging modality. The impact of SBI “attenuated gradually over time,” while the impact of white matter disease “appeared constant,” according to the researchers.

“The incidence of subsequent stroke in this population appears to be comparable to the incidence of recurrent stroke in some clinical trial populations examining secondary prevention strategies,” Kent and colleagues wrote. “The ability to identify these patients at scale represents a large opportunity for stroke prevention.”