Yield and cost of individual common diagnostic tests in new primary care outpatients in Japan

Abstract

Background: Appropriate diagnostic testing involves considerations of cost-effectiveness. We examined the cost-effectiveness of individual tests in a panel of tests defined by the Japan Society of Clinical Pathology. Methods: We studied 540 new, symptomatic primary care outpatients with a set of 30 common diagnostic tests [the Essential Laboratory Tests (2); ELT(2) panel] for clinical evaluation and identification of occult disease. A useful result (UR) of testing was defined as a finding that contributed to a change in a physician's diagnosis or decision-making relating to a "tentative initial diagnosis" obtained from history and physical examination alone. Results: The ELT(2) panel testing yielded 398 URs and uncovered 261 occult diseases among 540 patients. In total, 1592 tests contributed to either UR-generation or discovery of occult disease. The cost per effective test (cost required per test that contributed to either definition of effectiveness) ranged from ¥108 (∼US$0.92) for total cholesterol to ¥6200 (∼$52.50) for chest x-ray. Contribution rates and the cost per effective test varied among disease categories. We restructured panel components considering the effectiveness of each test. Subsets of the ELT(2) would have improved cost-effectiveness and achieved cost savings in five of eight disease categories. Conclusions: Assembly of tests based on cost-effectiveness can improve clinical efficiency and decrease total cost of panel testing for selected patient groups. © 2002 American Association for Clinical Chemistry.