Laboratory-Developed Tests Account for a Small Minority of Tests Ordered in an Academic Hospital System.

Abstract

To determine the frequency of use of laboratory-developed tests (LDTs) in an academic medical center system. Retrospective analysis of 2021 test order data from an academic medical center (hospital, outpatient clinics, and cancer center) was done. Measures included assay type, assay methodology, regulatory status, test order volume, inpatient vs outpatient setting, and provider medical specialty. Of the 3,016,928 tests ordered in 2021, 2,831,489 (93.9%) were tests cleared, approved, and/or authorized by the US Food and Drug Administration (FDA); 116,583 (3.9%) were LDTs; and 68,856 (2.3%) were standard methods. These test orders were performed using a total of 1,954 distinct assays. Of these, 983 (50.3%) were FDA assays, 880 (45.0%) were LDTs, and 91 (4.7%) were standard methods. Laboratory-developed tests were more commonly ordered in the outpatient vs inpatient setting and represented a higher proportion of the test volume at the cancer center compared with the university hospital (5.6% vs 3.6%, respectively). The top 167 LDT assays accounted for 90% of the LDT volume (104,996 orders). Among the 20 most frequently ordered LDTs were mass spectrometry assays and tests used in the care of immunocompromised patients. Internal/family medicine placed the greatest number of orders (1,044,642) and ordered one of the lowest proportions of LDTs (3.2%). Laboratory-developed tests made up a small percentage of the total laboratory tests ordered within the academic health system studied.