Evaluation of an immunoturbidimetric D-dimer assay and pretest probability score for suspected venous thromboembolism in a district hospital setting.

Venous thromboembolism is a leading cause of co-morbidity and death in hospital patients. This observational study looks at the usefulness of pretest probability and immunoturbidimetric D-dimer levels for the diagnosis of thromboembolic episodes in outpatients (108 of 197; 54.8%) and inpatients (89 of 197; 45.2%). Across 197 consecutive patients, D-dimers showed 100% sensitivity (95% CI, 87-100%). As a result, the combination of normal D-dimers and low or intermediate probability score yielded a negative predictive value of 100% (95% CI, 90.6-100%). The tests lacked specificity and positive predictive value. Normal D-dimer level in patients with low or intermediate pretest probability makes venous thromboembolism an unlikely diagnosis and may obviate the need for confirmatory scans. All other patients will need diagnostic imaging. Clinicians should be aware of the above utility and limitations while making management decisions for patients with suspected thromboembolism.