Combined use of clinical pretest probability and D-dimer test in cancer patients with clinically suspected deep venous thrombosis

BACKGROUND: The value of the D-dimer (DD) test in combination with the clinicalpretest probability (PTP) has not been evaluated in cancer patients withsuspected deep vein thrombosis (DVT), whereas this group of patients usuallyaccounts for 10-25% of clinically suspected DVT.METHODS: A cohort of 2066 consecutive patients with clinically suspected DVT was investigated. Patients were judged to be positive or negative for DVT accordingto the outcomes of serial compression ultrasound and a 3-month follow-up periodwith imaging test verification of the symptomatic cases. Diagnostic accuracyindices of the DD test according to the PTP score were assessed in patients with and without cancer.RESULTS: Of the cohort, 244 (11%) were known to have cancer at presentation. Avenous thromboembolic event was diagnosed in 41% of the patients with cancer and in 22% of the patients without malignancy. Among the cancer patients, 17% wereconsidered to have a low PTP, 35% a moderate and 41% a high PTP. The negativepredictive value (NPV) of the DD test was 100% (95% CI, 85-100) and 97% (95% CI, 88-99) among cancer patients with low PTP or low-moderate PTP. In the absence of malignancy, the corresponding NPV were 98% and 97%, respectively. The specificityof the DD test progressively decreased moving from the low to the higher PTP.CONCLUSIONS: In cancer patients with clinically suspected DVT, a negative DDmight be useful in excluding the diagnosis within the low or low-moderate PTPgroups. More studies are warranted to confirm these findings.