Development of a prediction model for deep vein thrombosis in a retrospective cohort of patients with suspected deep vein thrombosis in primary care.

OBJECTIVE: Early and accurate prediction and diagnosis of deep vein thrombosis (DVT) is essential to allow for immediate treatment and reduce potential complications. However, all potentially strong risk factors have not been included in pretest probability assessments such as the Wells score. In addition, the Wells score might not be suitable for use in primary care because it was developed for secondary care. We hypothesized that the addition of more risk factors for DVT to existing diagnostic approaches could improve the prediction of DVT. METHODS: All consecutive patients suspected of having DVT from 2004 to 2016 in a primary care setting were included in our retrospective study. All the patients had undergone Wells score, D-dimer, and duplex ultrasound assessments. The available recorded data of the patients were used to develop a model to predict DVT. RESULTS: Of 3381 eligible patients, 489 (14.5%) had confirmed DVT. The developed model, which included the D-dimer level, Wells score, gender, anticoagulation use, age, and family history of venous thrombosis, was able to distinguish patients with DVT among those with suspected DVT with a sensitivity of 82% (95% confidence interval, 78%-86%) and specificity of 82% (95% confidence interval, 80%-83%). CONCLUSIONS: The proposed model was able to predict for the presence of DVT among all patients with suspected DVT in a primary care setting with reasonable accuracy. Further validation in prospective studies is required.

Safe Exclusion of Deep Vein Thrombosis by a Rapid Sensitive ELISA D-dimer and Compression Ultrasonography in 1330 Outpatients With Suspected DVT.

Of 1330 outpatients with suspected deep vein thrombosis (DVT), a normal enzyme-linked immunosorbent assay (ELISA) d-dimer (VIDAS) of <500 ng/mL was true negative in 382 of 384 and false negative in compression ultrasonography (CUS) in 2, indicating a sensitivity of 99.52% and a negative predictive value (NPV) of 99.48%, with a specificity of 36% irrespective of clinical score. In 1059 outpatients with no DVT, the CUS was positive for the alternative diagnoses (AD): Bakers cyst, muscle hematoma, or old DVT in 62 (5.8%); superficial vein thrombosis without DVT in 78 (7.4%), and leg edema or varices in 17%. A second CUS in 641 patients was positive in 26 (4.0%), indicating an NPV of 96% after a first negative CUS. The NPV of the combination of a negative first CUS and a ELISA d-dimer test <1000 ng/mL was 99.1% at a specificity of 66.9%. As this strategy is cost effective by reduction in the need to repeat CUS by 67%, we designed a novel algorithm for the safe exclusion and diagnosis of DVT and AD for subsequent evaluation in a large prospective study.