Summary
It was the objective of this study to determine the proportion of patients who undergo
an appropriate diagnostic work-up following a D-dimer test performed to evaluate suspected
pulmonary embolism (PE) or deep vein thrombosis (DVT). We performed a retrospective
cohort study at a tertiary care hospital. We included patients if they underwent D-dimer
testing between 2002 and 2005, if the D-dimer was performed for evaluation of VTE,
and if the D-dimer test was successful. We classified: the patients’ clinical probability
of DVT or PE according to theWells models,the imaging results,and the appropriateness
of the testing algorithm. Of 1,000 randomly selected patients, 863 met our study criteria.
Seven hundred nineteen patients (83%) had testing during an emergency department visit,
while 144 were tested as inpatients (17%). Physicians performed the D-dimer test to
evaluate DVT and PE in 238 (28%) and 625 (72%) patients, respectively. Overall, the
testing strategy was appropriate in 69% (95% confidence interval [CI]: 66%–72%) of
cases. The testing strategy was more likely to be appropriate for emergency department
versus inpatients (75% vs. 39%, p < 0.05) and for DVT versus PE patients (84% vs.
63%, p < 0.05). Of all inappropriately tested patients, under-utilization of diagnostic
imaging was more common than over-utilization (90% vs. 10%, p < 0.05). VTE was confirmed
in 37 of 138 ‘DVT patients’ and 35 of 625 ‘PE patients’ (16% [95% CI: 11%–21%] and
6% [95% CI: 4%–8%], respectively). In conclusion, physicians often fail to use diagnostic
testing strategies for VTE correctly following a D-dimer test.
Keywords
Diagnostic tests - venous thromboembolism - D-dimer test
