The analysis of risk factors of pulmonary embolism in patients with negative D-dimer

Abstract

Objective To analyze the risk factors of pulmonary embolism in patients with negative D- dimer in serum in order to determine the need of pulmonary computed tomography angiograph (CTA) to confirm the final diagnosis in those patients for avoidance of misdiagnosis. Methods A retrospective analysis of 106 patients suspected to suffer from pulmonary embolism (PE) with serum negative D-dimer checked with pulmonary CTA was carried out. According to the results of CTA, the patients were divided into two groups, namely PE group (n=41) and non-PE group (n=65). The difference in clinic presentation, the time elapsed from onset to visit, N-terminal pro-brain natriuretic peptide (NT-proBNP) , high risk factors (such as immobilization for 3 weeks, leg swelling and pain to palpation, history of deep vein thrombosis, malignancy) and Wells score (≥4 points indicates probability of PE). And logistic regression analysis was made to investigate the risk factors in PE with negative D-dimer. Results The analysis study showed that 38.6% of total patients suspected to suffer from PE with serum negative D-dimer were checked by CTA to confirm the presence of PE. One important characteristics of the D-dimer negative PE patients was the longer time consumed from onset to visit [(9.51±2.01) d vs. (4.01±1.92) d, P <0.05] , and majority of the CTA positive patients suspected to suffer from PE with negative D-dimer had high risks of PE (P <0.01). Compared with the non-PE group, the Wells score ≥4 points and the level of serum NT-proBNP significantly increased in the PE group (P <0.01). Logistic regression analysis revealed that dyspnea, high NT-proBNP level and Wells sore ≥4 points were risk factors for D-dimer negative PE. Conclusion Delayed treatment was the main cause of misdiagnosis of D-dimer negative PE. Dyspnea, high NT-proBNP level and Wells sore ≥4 points were risk factors for suspected PE patients with negative D-dimer, and these patients should be confirmed by pulmonary CTA. On the contrary, PE could be excluded if patients with D-dimer negative had no these risk factors. Key words: D-dimer; Negative; Risk factor; N-terminal pro-brain natriuretic peptide; Pulmonary embolism