Echocardiography in patients with suspected endocarditis: a cost-effectiveness analysis.

PURPOSE We sought to determine the appropriate use of echocardiography for patients with suspected endocarditis. PATIENTS AND METHODS We constructed a decision tree and Markov model using published data to simulate the outcomes and costs of care for patients with suspected endocarditis. RESULTS Transesophageal imaging was optimal for patients who had a prior probability of endocarditis that is observed commonly in clinical practice (4% to 60%). In our base-case analysis (a 45-year-old man with a prior probability of endocarditis of 20%), use of transesophageal imaging improved quality-adjusted life expectancy (QALYs) by 9 days and reduced costs by $18 per person compared with the use of transthoracic echocardiography. Sequential test strategies that reserved the use of transesophageal echocardiography for patients who had an inadequate transthoracic study provided similar QALYs compared with the use of transesophageal echocardiography alone, but cost $230 to $250 more. For patients with prior probabilities of endocarditis greater than 60%, the optimal strategy is to treat for endocarditis without reliance on echocardiography for diagnosis. Patients with a prior probability of less than 2% should receive treatment for bacteremia without imaging. Transthoracic imaging was optimal for only a narrow range of prior probabilities (2% or 3%) of endocarditis. CONCLUSION The appropriate use of echocardiography depends on the prior probability of endocarditis. For patients whose prior probability of endocarditis is 4% to 60%, initial use of transesophageal echocardiography provides the greatest quality-adjusted survival at a cost that is within the range for commonly accepted health interventions.