Background: Determination of pretest probability and D-dimer tests are the first diagnostic steps in patients with suspected pulmonary embolism, which can be ruled out when clinical probability is unlikely and D-dimer level is normal. We evaluated the utility of D-dimer testing in patients with impaired renal function.
Methods: D-dimer tests were performed in consecutive patients with suspected pulmonary embolism and an unlikely clinical probability. Creatinine levels were assessed as clinical routine. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease formula. Correlation between D-dimer level and renal function and proportions of patients with normal D-dimer in different categories of estimated glomerular filtration rate (eGFR) were assessed. Different categories of decreasing eGFR were defined as: normal renal function (eGFR >89 mL/min), mild decrease in eGFR (eGFR 60-89 mL/min), and moderate decrease in eGFR (eGFR 30-59 mL/min).
Results: Creatinine levels were assessed in 351 of 385 patients (91%). D-dimer levels significantly increased in 3 categories of decreasing eGFR (P = .027 and P = .021 for moderate renal impairment compared with mild renal impairment and normal renal function, respectively). Normal D-dimer levels were found in 58% of patients with eGFR >89 mL/min, in 54% with eGFR 60-89 mL/min, and in 28% with eGFR 30-59 mL/min.
Conclusions: The specificity of D-dimer testing in patients with suspected pulmonary embolism and decreased GFR is significantly decreased. Nonetheless, performing D-dimer tests is still useful because computed tomography scanning can be withheld in a significant proportion of these patients.