Background: The objective was to determine whether variation in laboratory utilization exists and whether physicians were responsible for a portion of this variation.
Method: Variation in laboratory test ordering was collected on subspecialty services: the Medical Intensive Care Unit (MICU) and the Oncology Service. Ordinary least-squares regression was used to determine the effect of interns, residents, and attendings on the variation observed.
Results: Variation in laboratory utilization attributable to physicians exists. Housestaff explain a proportion of this variation on each subspecialty service.
Conclusions: Housestaff explain a large proportion of laboratory utilization attributable to physicians. This may represent an opportunity for education on systems-based practice and practice-based learning.