Full Length ArticleIs D-dimer used according to clinical algorithms in the diagnostic work-up of patients with suspicion of venous thromboembolism? A study in six European countries
Introduction
When reviewing a patient with suspected venous thromboembolism (VTE), i.e. pulmonary embolism (PE) or deep venous thromboembolism (DVT), it is recommended first to estimate the pre-test probability of PE/DVT by means of clinical signs and symptoms [1], [2], [3], [4], [5], [6]. This pre-test probability can be assessed either by using clinical experience or by calculating the probability based on scores i.e. clinical decision rules like the Wells scores for PE or DVT [5]. The rationale behind estimating the probability of VTE before further testing is to be able to select a safe and efficient diagnostic work-up based upon the recommended clinical algorithm [1], [2], [3], [4], [5], [6], [7], [8]. In patients with a low to moderate pre-test probability, a negative D-dimer is sufficient to exclude VTE, while in a patient with a higher pre-test probability, a negative D-dimer cannot exclude VTE, and the patient has to be referred to radiologic imaging to be able to exclude or confirm VTE. Patients with low to moderate pre-test probability and a positive D-dimer result, should also be referred to imaging [1], [2], [3], [4], [5], [6], [7], [8]. By using pre-test probability scores followed by the clinical algorithm described above, studies have shown that VTE can be ruled out without imaging in 30–40% of the patients where VTE is suspected [1], [3], [4], [5], [7], [8], [9], [10]. However, recent studies suggest that such pre-test probability scores and the clinical algorithm are not implemented in the routine diagnostic work-up of VTE in some countries [11], [12], [13], [14], [15], [16], [17]. The aim of this study was to explore how clinicians from several countries working in emergency departments investigate patients with suspected VTE in relation to their own estimated pre-test probabilities of VTE, and to compare this practice with the recommended clinical algorithm.
Section snippets
Methods
Two case histories followed by a questionnaire were developed by the members of the Working Group on Postanalytical Phase (WG-POST) of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) and the European Organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM), and were piloted by 1–5 physicians in Italy, Turkey, Norway, Hungary and Croatia. The case histories were slightly modified after the results from the pilot. During the summer of 2012,
Results
Altogether, 542 physicians responded to the questionnaire. General practitioners, laboratory physicians and medical students were excluded, leaving 487 physicians for further analyses. The response rate varied from 4.1% to 42.7% in the different countries (median 20.8%). Numerically, most responses were from Turkey and Norway (68%) (Table 1). Background characteristics of the physicians are outlined in Table 1. Eight percent did not answer all questions in Case A and B, and these physicians did
Case history A – clinical actions based on a negative D-dimer
Given a D-dimer of 0.45 mg/L (negative), 65% of physicians chose the “correct” clinical action based upon their own stated pre-test probability (Fig. 2A, Part II, green colours), 25% chose an action with “waste of resources” (Fig. 2A, Part II, yellow colour) and 11% an action which could be “hazardous” for the patient (Fig. 2A, Part II, red colour).
Discussion
The aim of this study was to explore how clinicians working in emergency departments investigated patients with suspected VTE in relation to their own estimated pre-test probabilities of VTE.
It is important to underline that the present study deals with the actions of the physicians after they have chosen a pre-test probability, and not if the pre-test probability chosen was correct based on the case history. The reason for not addressing the last question is that the case history can be
Conclusion
The findings in this study suggest that although pre-test probability scores are used, the recommended clinical algorithm following such scores, are not systematically adhered to by a substantial number of physicians. This could result in under- and over-diagnosing of patients, which can put the patients into significant risk [26]. Not following the algorithms also lead to an extra burden on the health care system by applying both D-dimer and imaging in a significant amount of the patients
Acknowledgements
We would like to thank all the national societies who kindly offered to recruit their member physicians to this study (Norwegian Society of Internal Medicine, Turkish Society of Internal Medicine, Hungarian Society of Emergency Medicine, Croatian Society of Cardiology, Italian Academy of Emergency Medicine Care, all the participating physicians and in addition Thomas H Røraas for statistical support and Silvia Cattaneo (EFLM) for SurveyMonkey support. We also wish to thank Andreas Hillarp and
References (32)
- et al.
Diagnosis of DVT: antithrombotic therapy and prevention of Thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines
Chest
(2012) - et al.
Clinical prediction rules for pulmonary embolism: a systematic review and meta-analysis
J. Thromb. Haemost.
(2010) - et al.
Adherence to PIOPED II investigators' recommendations for computed tomography pulmonary angiography
Am. J. Med.
(2013) - et al.
Probability scores and diagnostic algorithms in pulmonary embolism: are they followed in clinical practice?
Arch. Bronconeumol.
(2014) - et al.
Is the ordering of imaging for suspected venous thromboembolism consistent with D-dimer result?
Ann. Emerg. Med.
(2009) - et al.
Value of assessment of pretest probability of deep-vein thrombosis in clinical management
Lancet
(1997) - et al.
Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators
Am. J. Med.
(2006) - et al.
Accuracy and safety of pretest probability assessment of deep vein thrombosis by physicians in training using the explicit Wells clinical model
J. Thromb. Haemost.
(2006) - et al.
The interobserver reliability of pretest probability assessment in patients with suspected pulmonary embolism
Thromb. Res.
(2005) - et al.
The importance of clinical probability assessment in interpreting a normal d-dimer in patients with suspected pulmonary embolism
Chest
(2008)