Combined D-dimer and clinical probability are useful for exclusion of recurrent deep venous thrombosis

It is estimated that up to one-third of patients with a history of deep venous thrombosis (DVT) present with symptoms of recurrent DVT. Our objective was to investigate both the diagnostic value of D-dimer (DD) and safety of a standard diagnostic algorithm including clinical assessment, plasma DD levels, and compression venous ultrasound as diagnostic tools in outpatients presenting with clinically suspected acute recurrent DVT of the lower limbs. We have enrolled 105 outpatients with a previous history of confirmed DVT and clinically suspected recurrent DVT. A 3-month follow-up period was carried out for patients in whom DVT was initially excluded. Prevalence of DVT in our study population was 44.8% (47/105). DD was negative in 17.1% of cases (18/105) and DVT could be ruled out in 15.2% of patients evaluated (16/105) on the basis of an unlikely clinical probability and a negative DO result. Only one false negative DD result in a patient scored as likely for DVT was found. Sensitivity, specificity, positive and negative predictive value of DD for the diagnosis of DVT were 97.9% (95% CI 88.9-99.6%), 29.3% (95% CI 19.2-42.0%), 52.9% (95% CI 42.5-63.0) and 94.4% (95% CI 74.2%-99.0), respectively. Sensitivity was 100% (95% CI 75.7-100) in the group of patients in whom DVT was considered unlikely. A diagnostic strategy combining clinical evaluation and DD has proved to be useful for the exclusion of DVT in subjects with clinically suspected recurrent DVT, especially in patients included in the lower clinical pretest probability group.