Evaluation of a screening protocol to exclude the diagnosis of deep venous thrombosis among emergency department patients.

OBJECTIVE

The purpose of this study was to evaluate the efficacy and cost effectiveness of a deep venous thrombosis (DVT) screening protocol incorporating DVT pretest probability (PTP), selective D-dimer assay, and venous duplex imaging (VDI) to exclude the diagnosis of DVT among emergency department (ED) patients.

METHODS

A prospective study of all patients evaluated in the ED for suspected DVT during 1 year was undertaken. Patients were classified into PTP risk category by ED physicians before VDI. Correlation studies were completed using VDI as the gold standard. Charges associated with the protocol were calculated.

RESULTS

One hundred fourteen patients were included. The incidence of DVT was 9.6% (11). Thirty-six (55%) patients were classified as high risk, 23 (35%) as moderate, and 7 (10%) as low risk. All patients diagnosed with DVT were in the high-risk group (incidence, 16.7%). The sensitivity and negative predictive value were both 100% when PTP and D-dimer were used, but fell to 80% and 95%, respectively, when only D-dimer was considered. The true negative rates were 23% and 37%, respectively. Based on this study, we propose the following screening: for high-risk patients, use direct VDI (no D-dimer); for low-risk or moderate-risk patients, obtain D-dimer, and if it is positive, use VDI, and if it is negative, no further action is required. The average charge associated with the protocol was 170.50 dollars as opposed to 202.00 dollars for global VDI.

CONCLUSION

A screening protocol using PTP along with selective D-dimer and VDI to exclude the diagnosis of DVT among ED patients is efficacious and cost efficient. This screening approach establishes criteria to satisfy billing requirements, can eliminate unnecessary VDI in 23% of ED referrals, and can reduce charges by 16%.