The Yield of Computed Tomography of the Head Among Patients Presenting With Syncope: A Systematic Review

Abstract

Background: Overuse of head computed tomography (CT) for syncope has been reported. However, there is no literature synthesis on this overuse. We undertook a systematic review to determine the use and yield of head CT and risk factors for serious intracranial conditions among syncope patients. Methods:We searched Embase, Medline, and Cochrane databases from inception until June 2017. Studies including adult syncope patients with part or all of patients undergoing CT head were included. We excluded case reports, reviews, letters, and pediatric studies. Two independent reviewers screened the articles and collected data on CT head use, diagnostic yield (proportion with acute hemorrhage, tumors or infarct), and risk of bias. We report pooled percentages, I 2 , and Cochran's Q-test.Results: Seventeen articles with 3,361 syncope patients were included. In eight ED studies (n = 1,669), 54.4% (95% confidence interval [CI] = 34.9%-73.2%) received head CT with a 3.8% (95% CI = 2.6%-5.1%) diagnostic yield and considerable heterogeneity. In six in-hospital studies (n = 1,289), 44.8% (95% CI = 26.4%-64.1%) received head CT with a 1.2% (95% CI = 0.5%-2.2%) yield and no heterogeneity. In two articles, all patients had CT (yield 2.3%) and the third enrolled patients ≥ 65 years old (yield 7.7%). Abnormal neurologic findings, age ≥ 65 years, trauma, warfarin use, and seizure/stroke history were identified as risk factors. The quality of all articles referenced was strong.Conclusion: More than half of patients with syncope underwent CT head with a diagnostic yield of 1.1% to 3.8%. A future large prospective study is needed to develop a robust risk tool. S yncope is defined as a sudden and brief loss of consciousness (LOC) due to transient global cerebral hypoperfusion, followed by spontaneous and complete recovery. 1 It accounts for 1% to 3% of emergency department (ED) visits. 1-4 Among ED patients with syncope, 7% to 23% will have serious underlying conditions identified either in the ED or within 30 days of their index visit. 5-8 Previous studies have reported 2.3% to 4.4% incidence of serious intracranial conditions (subarachnoid hemorrhage, subdural hematoma, space-occupying lesion, or intraparenchymal infarct or hemorrhage) among

Moving Beyond Diagnostic Accuracy With Systematic Reviews and Meta‐analyses

“…This approach is particularly important for heterogeneous conditions such as syncope. The systematic review by Viau et al . likely overreports the proportion having a serious diagnosis as the proportion of syncope cases undergoing head CT was only about half.…”

“…While this systematic review fails to produce an exact diagnostic yield for CT scan of the head in patients with syncope due to certain limitations, it produces valuable information that could be used in clinical practice . The authors of the systematic review recommend estimating a pretest probability for serious intracranial pathologies for each patient with syncope before ordering the test.…”

“…This pretest probability is estimated based on patients’ risk factors, possibility of other pathologies mimicking syncope (e.g., seizure), and also preferences. The authors suggest that when this assessment generates a low pretest probability, CT scan of the head should be deferred …”

“…In this issue of Academic Emergency Medicine , Viau et al . assess the yield of computed tomography (CT) of the head among patients presenting with syncope.…”

“…Approximately half of these ED patients underwent head CT with a 1.2 and 3.8% yield of serious intracranial conditions identified in admitted patients and ED patients, respectively. Serious intracranial conditions were selected based on clinical relevance, previous literature, and consensus among the coauthors . While this systematic review is not directly a diagnostic accuracy trial, it gives us an opportunity to discuss how to appraise the evidence pertaining to diagnostic tests within the context of clinical efficiencies in an era of value‐based purchasing.…”