Andrew Dunn, MD, FACP
Is computed tomographic pulmonary angiography (CTPA) at least as safe as ventilation-perfusion (V/Q) lung scanning for ruling out pulmonary embolism (PE) in adults with acute symptoms?
Randomized, controlled, noninferiority trial.
Blinded (clinicians, outcome assessors during initial assessment, and adjudication committee).*
Outpatient clinics, emergency departments, and inpatient units of 5 academic health care centers in Canada and the USA.
1417 patients ≥ 18 years of age (mean 53 y, 62% women) who presented with signs and symptoms of acute PE, with or without signs of deep venous thrombosis (DVT); and were assessed to be clinically likely (Wells model score ≥ 4.5) or unlikely (score < 4.5) to have PE but with a positive D-dimer test. Exclusion criteria included PE or DVT in the past 3 months; unchanged pulmonary symptoms in the past 2 weeks; need for long-term anticoagulants; use of therapeutic doses of parenteral anticoagulants for > 48 hours; life expectancy < 3 months; contraindication to contrast media; and pregnancy.
Initial diagnostic imaging with CTPA (n = 701) or V/Q scan (n = 716). CTPA was done with either single (n= 195) or multidetector (n= 499) systems. Patients with positive CTPA or high-probability V/Q scans were considered to have PE; patients with normal V/Q scans were considered to have PE excluded. All other patients had leg ultrasonography (US). Management was based on clinical likelihood of PE, D-dimer, and US results. Patients diagnosed with PE or DVT were anticoagulated.
Development of DVT or PE at 3 months in patients in whom PE had initially been ruled out; and death.
99% (intention-to-treat analysis).
In the initial diagnostic period, 234 patients (17%) were diagnosed with PE or DVT. Among the 1172 patients in whom venous thromboembolism (VTE) was initially excluded as a diagnosis, the CTPA and V/Q groups did not differ for VTE at 3 months (Table); the between-group difference of −0.6% (95% CI −1.6 to 0.3) met the prespecified criteria for noninferiority (i.e., < 2.5% absolute difference between groups). The groups did not differ for mortality (Table).
Computed tomographic pulmonary angiography was not inferior to ventilation–perfusion lung scanning as part of a diagnostic-management strategy for ruling out pulmonary embolism.
Computed tomographic pulmonary angiography (CTPA) vs ventilation–perfusion lung scanning (V/Q) for detection of pulmonary embolism (PE)†
†DVT = deep venous thrombosis; NS = not significant; other abbreviations defined in Glossary. RRR, NNT, and CI calculated from data in article. Analysis based on 1172 patients in whom PE was ruled out during initial testing.
Dunn A. CT pulmonary angiography was not inferior to ventilation–perfusion lung scanning for ruling out pulmonary embolism. Ann Intern Med. 2008;148:JC4–10. doi: 10.7326/0003-4819-148-12-200806170-02010
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Published: Ann Intern Med. 2008;148(12):JC4-10.
Emergency Medicine, Pulmonary Embolism, Pulmonary/Critical Care, Venous Thromboembolism.
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