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I agree with Dr Laks' comments that aggressive investigations into the diagnostic accuracy of combinations of noninvasive determinations and ventilation/perfusion scanning are needed. While we are waiting for such studies, clinicians need to have some basis for decision making, using information currently available. The PIOPED study looked at the diagnostic accuracy of clinical suspicion of pulmonary embolism and the ventilation/perfusion scan.Dr Laks' statements, however, are not relevant for the patient with normal findings from noninvasive leg studies. The PIOPED study did not address impedence plethysmography and duplex ultrasound, yet these techniques are used in patients with suspected pulmonary embolism. One is left, then, with balancing the associated risk-benefit ratios of angiogram vs anticoagulation for a patient who may or may not have pulmonary embolism. The relative risk of anticoagulation is greater than the risks inherent to angiography.Also, a relative bias exists when the diagnosis of pulmonary
Bone RC. The Diagnosis of Pulmonary Embolism-Reply. JAMA. 1990;264(20):2625. doi:10.1001/jama.1990.03450200031017