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Exclusion and diagnosis of deep vein thrombosis in outpatients by sequential noninvasive tools
J J Michiels1, H Kasbergen, R Oudega
1Hemostasis and Thrombosis Research, Department of Hematology, University Hospital Antwerp, Belgium. postbus@goodheartcenter.demon.nl
Insights
Deep vein thrombosis (DVT) diagnosis can be improved using clinical scores and D-dimer testing alongside compression ultrasonography (CUS). This strategy enhances diagnostic accuracy and cost-effectiveness for suspected DVT cases.
Area of Science:
- Vascular Medicine
- Diagnostic Imaging
- Clinical Pathology
Background:
- Phlebography, the gold standard for deep vein thrombosis (DVT) diagnosis, has been largely replaced by compression ultrasonography (CUS) due to its invasive nature.
- Compression ultrasonography (CUS) confirms DVT in only 16-28% of outpatients, missing calf vein thrombosis despite a high positive predictive value for proximal DVT.
- Serial CUS is often recommended for suspected DVT but is costly and can be optimized by integrating clinical scores and D-dimer testing.
Purpose of the Study:
- To evaluate the efficacy of combining clinical scores and D-dimer testing with CUS for the accurate and cost-effective diagnosis of DVT.
- To determine the negative predictive value of various diagnostic strategies for excluding DVT in outpatients.
- To establish an optimized diagnostic pathway for suspected DVT that minimizes unnecessary testing.
Main Methods:
- Analysis of diagnostic performance metrics including sensitivity, specificity, and predictive values.
- Assessment of DVT prevalence in different clinical score subgroups (low, moderate, high).
- Evaluation of combined diagnostic strategies: CUS, clinical score, and rapid ELISA D-dimer testing.
Main Results:
- A low clinical score combined with a negative rapid ELISA D-dimer test achieves a negative predictive value >99.9% for DVT exclusion, obviating the need for CUS.
- Combining negative CUS and negative rapid ELISA D-dimer test safely excludes DVT regardless of clinical score.
- Specific combinations of CUS, clinical score, and D-dimer levels guide decisions on repeat CUS, particularly for moderate to high clinical scores.
Conclusions:
- Integrating rapid ELISA D-dimer testing with clinical assessment and CUS offers a more cost-effective and efficient strategy for diagnosing DVT.
- A negative rapid ELISA D-dimer test in low-risk patients effectively rules out DVT, simplifying diagnostic protocols.
- Risk-stratified application of CUS, guided by D-dimer results and clinical scores, optimizes DVT management and resource utilization.
Abstract:
Phlebography is the reference gold standard for the diagnosis of deep vein thrombosis (DVT), but due to its invasive nature and associated side effects it has been replaced by compression ultrasonography (CUS). Patients suspected of DVT are subjected to leg vein CUS that actually confirms DVT in only 16 to 28% of outpatients in large prospective management studies. CUS has a high positive predictive value of more than 98% for proximal DVT but usually misses calf vein thrombosis. Its negative predictive value for proximal DVT is about 97-98%, on the basis of which repeated scanning at day 7 after a negative first CUS (serial CUS) in outpatients with a first suspicion of DVT is advocated. Serial ultrasonography is costly and can be simplified and improved by the addition of clinical score and D-dimer testing. The safe exclusion of DVT by a rapid sensitive D-dimer test in combination with clinical score and/or CUS requires a negative predictive value of >99%. The negative predictive value for DVT is determined by the sensitivity of the rapid ELISA D-dimer test and the prevalence of DVT in subgroups of outpatients suspected of the condition. The prevalence of DVT in outpatients with a low, moderate and high clinical score varies widely from 3-10%, 15-30% and >70%, respectively. The combination of a low clinical score (prevalence DVT 3-5%) and a negative rapid ELISA D-dimer alone test will have a very high negative predictive value of >99.9% to exclude DVT without the need of CUS testing. The combination of a negative CUS and a negative rapid ELISA D-dimer test safely excludes DVT in patients with suspected DVT irrespective of the clinical score. The combination of a negative CUS, a low clinical score and a positive ELISA D-dimer but <1000 ng/ml excludes DVT with a negative predictive value of >99% without the need to repeat CUS. Patients with a negative CUS, scan but a positive ELISA D-dimer, and a moderate or high clinical score are still at risk with a probability of DVT of 3-5% and 20-30%, respectively and are thus candidates for repeated ultrasound scanning. The rapid ELISA D-dimer first followed by risk-based no, single or repeated CUS will be the most cost-effective strategy.