Effects of impaired renal function on levels and performance of D-dimer in patients with suspected pulmonary embolism.

Clinical probability and D-dimer measurement play an essential role in the non-invasive diagnostic strategies for pulmonary embolism (PE). PE can be ruled out without further imaging in patients with non-high clinical probability and negative D-dimer. D-dimer level is increased in patients with renal impairment. Whether its diagnostic usefulness is maintained in these patients is not well determined. We aimed to evaluate the effects of renal impairment on diagnostic performances of D-dimer in patients with suspected PE. A retrospective analysis of 1,625 patients with suspected PE included in a multicentre prospective study was performed. D-dimer levels and percentages of patients with a negative D-dimer were compared between three subgroups according to glomerular filtration rate (GFR) estimated by the MDRD formula: ≥90 ml/min (normal renal function), 60-89 ml/min (mild renal impairment), 30-59 ml/min (moderate renal impairment). D-dimer levels increased and the proportion of negative D-dimer decreased significantly according to renal status: 46% negative D-dimer in patients with normal GFR, 31% in patients with mild renal impairment, 11% in those with moderate renal impairment, corresponding to number of patients needed to test to obtain one negative test of 2.2, 3.2 and 9, respectively. In conclusion, the clinical usefulness of D-dimer decreases with renal impairment. However, PE can still be ruled out by negative D-dimer in a substantial proportion of patients with non-high clinical probability, avoiding exposure to contrast media.