A comparison of computerised strain gauge plethysmography with D-dimer testing in screening for deep-vein thrombosis

Diagnosis of deep vein thrombosis of the lower extremity: a systematic review and meta-analysis of test accuracy

Deep vein thrombosis (DVT) of the lower extremities can be associated with significant morbidity and may progress to pulmonary embolism and postthrombotic syndrome. Early diagnosis and treatment are important to minimize the risk of these complications. We systematically reviewed the accuracy of diagnostic tests for first-episode and recurrent DVT of the lower extremities, including proximal compression ultrasonography (US), whole leg US, serial US, and high-sensitivity quantitative D-dimer assays. We searched Cochrane Central, MEDLINE, and EMBASE for eligible studies, reference lists of relevant reviews, registered trials, and relevant conference proceedings. Two investigators screened and abstracted data. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 and certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation framework. We pooled estimates of sensitivity and specificity. The review included 43 studies. For any suspected DVT, the pooled estimates for sensitivity and specificity of proximal compression US were 90.1% (95% confidence interval [CI], 86.5-92.8) and 98.5% (95% CI, 97.6-99.1), respectively. For whole-leg US, pooled estimates were 94.0% (95% CI, 91.3-95.9) and 97.3% (95% CI, 94.8-98.6); for serial US pooled estimates were 97.9% (95% CI, 96.0-98.9) and 99.8% (95% CI, 99.3-99.9). For D-dimer, pooled estimates were 96.1% (95% CI, 92.6-98.0) and 35.7% (95% CI, 29.5-42.4). Recurrent DVT studies were not pooled. Certainty of evidence varied from low to high. This systematic review of current diagnostic tests for DVT of the lower extremities provides accuracy estimates. The tests are evaluated when performed in a stand-alone fashion, and in a diagnostic pathway. The pretest probability of DVT often assessed by a clinical decision rule will influence how, together with sensitivity and specificity estimates, patients will be managed.

American Society of Hematology 2018 guidelines for management of venous thromboembolism: diagnosis of venous thromboembolism

BACKGROUND

Modern diagnostic strategies for venous thromboembolism (VTE) incorporate pretest probability (PTP; prevalence) assessment. The ability of diagnostic tests to correctly identify or exclude VTE is influenced by VTE prevalence and test accuracy characteristics.

OBJECTIVE

These evidence-based guidelines are intended to support patients, clinicians, and health care professionals in VTE diagnosis. Diagnostic strategies were evaluated for pulmonary embolism (PE), deep vein thrombosis (DVT) of the lower and upper extremity, and recurrent VTE.

METHODS

The American Society of Hematology (ASH) formed a multidisciplinary panel including patient representatives. The McMaster University GRADE Centre completed systematic reviews up to 1 October 2017. The panel prioritized questions and outcomes and used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess evidence and make recommendations. Test accuracy estimates and VTE population prevalence were used to model expected outcomes in diagnostic pathways. Where modeling was not feasible, management and accuracy studies were used to formulate recommendations.

RESULTS

Ten recommendations are presented, by PTP for patients with suspected PE and lower extremity DVT, and for recurrent VTE and upper extremity DVT.

CONCLUSIONS

For patients at low (unlikely) VTE risk, using D-dimer as the initial test reduces the need for diagnostic imaging. For patients at high (likely) VTE risk, imaging is warranted. For PE diagnosis, ventilation-perfusion scanning and computed tomography pulmonary angiography are the most validated tests, whereas lower or upper extremity DVT diagnosis uses ultrasonography. Research is needed on new diagnostic modalities and to validate clinical decision rules for patients with suspected recurrent VTE.

Is there still a role for computerized strain gauge plethysmography in the assessment of patients with suspected deep vein thrombosis?

INTRODUCTION

Although deep vein thromboses (DVTs) are common, only a minority of patients referred with suspected DVT will have the condition. Various strategies exist to allow rapid and safe discharge of low-risk patients, thus precluding the need for imaging.

AIMS AND OBJECTIVES

We aimed to investigate the accuracy of clinical risk assessment, D-Dimer analysis, computerized strain gauge plethysmography (CSGP) or a combination of the above in the assessment of outpatients with suspected DVT.

METHODS

We performed a prospective cohort study on outpatients referred with suspected DVT to our medical assessment unit. Patients systematically underwent clinical risk assessment, D-Dimer analysis, CSGP and imaging with ultrasonography and/or venography.

RESULTS

One hundred and eighty patients with suspected DVT were included in the analysis. Using a threshold of 0.6 mg/l, D-Dimer had a sensitivity and negative predictive value (NPV) of 100% for detecting DVT. Incorporating D-Dimer analysis with clinical risk assessment increased the specificity of the test. The sensitivity and NPV of CSGP were poor at 52.8 and 86.7%, respectively. Incorporating CSGP with D-Dimer did not influence decision making. Although the sensitivity of CSGP was higher for above knee (73.7%) than below knee DVT (29.4%), neither was sufficient for use as a screening tool.

CONCLUSION

Our study did not support the role of CSGP either as a stand-alone screening tool or in conjunction with clinical risk scoring. As the evidence base for CSGP is conflicting, its accuracy should first be assessed before being incorporated into hospital algorithms as a DVT exclusion tool. However, our results support the current practice for D-Dimer use either alone or in conjunction with clinical assessment tool in the assessment of lower limb DVT.