THE ROLE OF PLASMA D-DIMER CONCENTRATION IN THE EXCLUSION OF PULMONARY-EMBOLISM

Objective. To determine the role of four ELISA D-dimer assays in the e xclusion of pulmonary embolism. Design. Blinded comparison using pulmo nary angiography and/or lung scintigraphy as a reference method. Setti ng. A secondary and tertiary referral centre. Patients and methods. Co nsecutive patients with suspected pulmonary embolism underwent lung sc intigraphy, followed by angiography if a non-diagnostic result was obt ained. Comorbid conditions resulting in elevated plasma D-dimer levels were defined a priori. Cut-off levels for 100% sensitivity were deter mined. A decision-analytic model was used to determine effectiveness a nd costs in the management pulmonary embolism. Main outcome measures. The exclusion efficacy of the various assays at a sensitivity of 100%, and cost-effectiveness. Results. A total of 179 patients were include d (78 inpatients and 101 outpatients; 74 patients had comorbid conditi ons). Pulmonary embolism could be adequately excluded in between 8% an d 18% of all patients, and in between 3% and 7% and 11% and 27% of inp atients and outpatients, respectively, depending on the assay used. D- dimer assays could exclude pulmonary embolism in < 5% of patients with comorbid conditions, whereas this increased to 14-32% in outpatients without comorbid conditions. A cost-effectiveness analysis showed a co st reduction of 10% at a specificity of 30%, largely due to a 28% decr ease in angiography requirements. Furthermore, for every 2% decrease i n sensitivity, one per 1000 evaluated patients would die as a result o f inadequately treated pulmonary embolism. Conclusion. D-dimer ELISA a ssays may have a role in the exclusion of pulmonary embolism in sympto matic outpatients, where the application may reduce angiography by 30% and costs by 10%.