A Normal D-dimer and a Low Clinical Probability Test Safely Excludes Venous Thromboembolism. A Follow-up D-dimer Adds No Further Information

Abstract number: P0468

Ljungqvist¹ M, Ahlgren¹ A, Moritz² P, Söderberg¹ M, Lärfars¹ G

¹¹Dept of Medicine, Stockholm Söder Hospital, Stockholm, Sweden ¹¹Dept of Medicine, Stockholm Söder Hospital, Stockholm, Sweden ²²Accident and Emergency Dept, Stockholm Söder Hospital, Stockholm, Sweden

Background:  Deep vein thrombosis (DVT) and pulmonary embolism (PE) are common conditions at the Emergency Room (ER). The diagnosis is often a challenge because the clinical signs and symptoms are not sufficient to establish or exclude the disease. Previous studies have shown that in patients with low clinical probability a normal D-dimer safely obviates the need for further investigation.

Aims:  The aim of this study was to find out if a low clinical probability using Wells pre-test probability score together with a normal D-dimer safely exclude venous thromboembolism (VTE) in out-patients at our hospital and, if a follow up D-dimer test increases the negative probability value of the method.

Methods:  130 patients (68% women) presenting at the ER with suspected VTE and a low pre-test probability score according to Wells and a normal D-dimer test (TinaQuant^®) were included in the study. Exclusion criteria were an elevated D-dimer (i.e. >0.5 mg/L) and/or high clinical probability according to Wells score. A follow-up D-dimer test was made 3–7 days after inclusion and if abnormal additional investigations were made to exclude a VTE. All patients were contacted by phone after 3 months.

Results:  There were 101 (78%) patients with suspected DVT and 29 (22%) with suspected PE in the study. 101/130 (78%) had a follow-up D-dimer, and in 13 (13%) patients the second test was elevated. None of these had VTE. 128/130 (98%) had a follow-up after 3 months, none of these patients reported any clinical signs of VTE. The study is ongoing and an intermediate result will be presented at the congress.

Conclusion:  A normal pre-test probability score according to Wells and a normal D-dimer safely exclude VTE. A follow-up D-dimer test adds no further information.