Renal Function–Adjusted d-Dimer Levels in Critically Ill Patients With Suspected Thromboembolism*

Objectives: Diagnosing thromboembolic disease typically includes d -dimer testing and use of clinical scores in patients with low to intermediate pretest probability. However, renal dysfunction is often observed in patients with thromboembolic disease and was previously shown to be associated with increased d -dimer levels. We seek to validate previously suggested estimated glomerular filtration rate–adjusted d -dimer cutoff levels. Furthermore, we strive to explore whether the type of renal dysfunction affects estimated glomerular filtration rate–adjusted d -dimer test characteristics. Design: Single-center retrospective data analysis from electronic healthcare records of all emergency department patients admitted for suspected thromboembolic disease. Setting: Tertiary care academic hospital. Subjects: Exclusion criteria were as follows: age less than 16 years old, patients with active bleeding, and/or incomplete records. Interventions: Test characteristics of previously suggested that estimated glomerular filtration rate–adjusted d -dimer cutoff levels (> 333 µg/L [estimated glomerular filtration rate, > 60 mL/min/1.73 m 2 ], > 1,306 µg/L [30–60 mL/min/1.73 m 2 ], and > 1,663 µg/L [< 30 mL/min/1.73 m 2 ]) were validated and compared with the conventional d -dimer cutoff level of 500 µg/L. Main Results: A total of 14,477 patients were included in the final analysis, with 467 patients (3.5%) diagnosed with thromboembolic disease. Renal dysfunction was observed in 1,364 (9.4%) of the total population. When adjusted d -dimer levels were applied, test characteristics remained stable: negative predictive value (> 99%), sensitivity (91.2% vs 93.4%), and specificity (42.7% vs 50.7%) when compared with the conventional d -dimer cutoff level to rule out thromboembolic disease (< 500 µg/L). Comparable characteristics were also observed when adjusted d -dimer cutoff levels were applied in patients with acute kidney injury (negative predictive value, 98.8%; sensitivity, 95.8%; specificity, 39.2%) and/or “acute on chronic” renal dysfunction (negative predictive value, 98.0%; sensitivity, 92.9%; specificity, 48.5%). Conclusions: d -Dimer cutoff levels adjusted for renal dysfunction appear feasible and safe assessing thromboembolic disease in critically ill patients. Furthermore, adjusted d -dimer cutoff levels seem reliable in patients with acute kidney injury and “acute on chronic” renal dysfunction. In patients with estimated glomerular filtration rate less than 60 mL/min/1.73 m 2 , the false-positive rate can be reduced when estimated glomerular filtration rate–adjusted d -dimer cutoff levels are applied.