Cost-effective Approaches to the Diagnosis of Pulmonary Embolism-Reply

Merrill's statement that "the effectiveness of this approach [serial leg testing], however, is not so clearly defined" is incorrect. Our prospective cohort study¹ evaluated the effectiveness of serial noninvasive leg testing, and the safety of withholding anticoagulant therapy if the results of this testing were negative, even though pulmonary embolism may have remained undetected. The effectiveness of serial noninvasive leg testing was evaluated by measuring clinical outcome on long-term follow-up, and our study clearly did so. Furthermore, Merrill's statement that "not treating these patients [with pulmonary embolism] is likely to result in a poor outcome" is an opinion that is not supported by the outcome data from our prospective study. The cohort with negative results on serial leg testing had a low rate of venous thromboembolism on follow-up: pulmonary embolism, 0.6% (4 of 627 patients); deep vein thrombosis, 1.3% (8 of 627 patients).1 This outcome is similar to that