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.