Hypothesis The risk of Venous Thromboembolism (VTE) including Pulmonary Embolism (PE) increases proportionately with the level of d-dimers.
Introduction The risk of PE/VTE is low when the values of d-dimers are below the reference range (1) (<500 ng/ml in our hospital). There is no clear evidence to suggest that risk of VTE increases proportionately with rising levels of d-dimers. We studied the correlation between the various values of d-dimers and the associated risk of having a PE/VTE.
Methods Data was collected retrospectively from March 2011 to Feb 2012. For the study we divided the patients into 3 risk groups based on d-dimers. Group1: 500–1000; Group 2: 1000–5000; Group 3: >5000. Each group was analysed by separate individual. Data was collected by selecting only those patients who had definitive scan to investigate for PE/VTE Results
See Table When d-dimers are >5000, the risk of PE/VTE is significantly elevated when compared to <5000. (p value <0.0005)
When the d-dimers are > 5000, it’s a good predictor of central PE (p value <0.0005) or Proximal DVT (p value <0.0005).
Conclusion Our study suggests that when the d-dimers are significantly elevated (>5000) the associated risk of VTE (PE and DVT) is significantly elevated. The risk appears to increase proportionately until the value of 5000 beyond which it increases exponentially. Levels >5000 strongly predicts the likelihood of a central PE or a proximal DVT. Clinicians could use this as an additional indicator to thrombolyse PE’s in absence of confirmatory test. Further validity studies will be required to confirm this.
Dr Stein et Al: d-Dimer for the Exclusion of Acute Venous Thrombosis and Pulmonary Embolism; Ann Intern Med. 2004;140(8):589–602.doi:10.7326/0003–4819–140-8–200404200–00005