What are effective strategies in diagnosing venous thromboembolic events in primary care?
The main points of these guidelines to the diagnosis of venous thromboembolic events (VTE) are: 1. Begin by using validated clinical prediction rules, like the Wells prediction rule, to estimate the clinical likelihood of VTE. 2. In patients with a low clinical likelihood of VTE, a negative result from a high-sensitivity D-dimer test confirms that the patient is unlikely to have a VTE. 3. Perform an ultrasound of the lower extremities in patients with intermediate to high clinical likelihood of VTE. 4. Patients with intermediate or high clinical likelihood of pulmonary embolism require diagnostic imaging studies. (LOE = 1a)
Qaseem A, Snow V, Barry P, et al, for the Joint American Academy of Family Physicians/American College of Physicians Panel on Deep Venous Thrombosis/Pulmonary Embolism. Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med 2007;5:57-62. [PMID:17261865]
This clinical practice guideline was derived from a well-done systematic review of the literature* performed by the Agency for Healthcare Research and Quality Evidence-Based Practice Centers. The guideline is aimed at any clinician who diagnoses VTE; there is an accompanying guideline on managing VTE.** The guideline answers questions about the role of clinical prediction rules, D-dimer tests, ultrasounds, and computed axial tomography (CT) in the diagnosis of VTE. The authors found 19 studies using clinical prediction rules, 17 of which used the Wells prediction rule. These studies support the use of prediction rules. With the combination of a negative D-dimer result and a negative clinical prediction rule in low-risk patients, the probability of VTE is quite low. The authors found 4 studies evaluating D-dimer testing without the concomitant use of a clinical prediction rule. These studies support the theory that a negative result from a highly sensitive D-dimer test can exclude VTE in low-risk patients. The evidence-based practice center review found ultrasound to be very sensitive (89%-96%) and specific (94%-99%) in diagnosing symptomatic proximal vein lower extremity thromboses. It is less sensitive in asymptomatic thromboses (47%-62%). The studies of CT were of variable quality and the results were less consistent. Because of this, further imaging is likely needed in patients who have a high pretest probability of pulmonary embolism and a negative CT scan result. *Segal JB, et al. Ann Fam Med 2007;5:63-73. ** Snow V, et al. Ann Fam Med 2007;5:74-80
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