Incidental Detection of Previously Unknown Strokes on Head CT Examinations: An Untapped Opportunity for Secondary Prevention.

Abstract

Background: The incidental discovery of previously unknown strokes on neuroimaging is an opportunity to implement secondary prevention, reducing the risk of recurrent strokes by up to 80%.

Objective: To evaluate the prevalence of previously unknown strokes on emergency department (ED) head CT imaging and identify associated patient and imaging factors.

Methods: Retrospective study of adult patients receiving head CT (age ≥ 18 years) at three EDs between July and December 2023. Old strokes on CT imaging were categorized as previously known or unknown. Patient and imaging factors associated with unknown strokes were assessed via univariable regression, multivariable regression, and decision tree analysis.

Results: In 21,985 ED encounters with head CT, 869 (4.0%) examinations demonstrated an old stroke (mean age, 74.4 years ± 14.0 [SD]), of which 372 (43%; 1.7% of all CTs) were unknown. Univariable analysis showed that unknown strokes were associated with greater age (odds ratio [OR], 1.03; 95% confidence interval [CI]: 1.02-1.04; P < .001), a single site of old stroke (OR, 2.7; 95% CI: 2.06-3.58; P and < .001), smaller strokes (OR, 1.8, 95% CI: 1.6-2.0, P < .001), as well as gangliocapsular (OR, 2.8; 95% CI: 1.9-4.0; P < .001) and cerebellar location (OR, 2.1; 95% CI: 1.4-3.2; P < .001). Results of further analyses corroborated those of the univariable regression.

Conclusion: More than a third of old strokes on head CT imaging are unknown to patients and clinicians. Capturing this opportunity for secondary prevention could benefit 100,000 to 200,000 patients per year in the United States, based on trends in ED care.