D-dimer and Body CT to Identify Occult Malignancy in Acute Ischemic Stroke

Patients with acute ischemic stroke associated with cancer have D-dimer elevations greater than those with acute ischemic stroke or cancer alone. While D-dimer has been proposed as a screening tool to identify such patients, its use in clinical practice to identify malignancy and to inform the use of CT scanning has not been well characterized.

We conducted a retrospective cohort study of patients with acute ischemic stroke to evaluate how D-dimer levels and CT chest, abdomen, and pelvis scanning were used in practice to screen for occult malignancy. Patients were excluded if they had known active cancer and or received tPA.

Of 480 patients, 254 (53%) had D-dimer measured, 49 (10%) underwent CT screening for cancer, and 11 (2%) had findings concerning for malignancy. There was no difference in D-dimer level between patients who underwent CT evaluation for cancer and those who did not (median 1.01 vs 0.85 p = 0.19). Patients with CT concerning for cancer had higher D-dimer levels than those with a negative CT (median 2.52 vs 0.74 p = 0.01). D-dimer demonstrated moderate discrimination with a c-statistic of 0.77. Selecting a cut point of >1.2 ug/mL (60^th percentile of our cohort and 2.4-times the upper limit of normal for our institution's D-dimer assay) provided a sensitivity of 85% and specificity of 65%, a positive likelihood ratio of 2.32, and an odds ratio of 9.6 (95% confidence interval 2.1-44.1, p = 0.004) for having a CT scan concerning for malignancy.

Elevated D-dimer levels are suggestive of occult malignancy in acute ischemic stroke patients and should inform selective use of CT to screen for cancer.