The Incidence of Un-indicated Preoperative Testing in a Tertiary Academic Ambulatory Center: a Retrospective Cohort Study

Background: Despite existing evidence and guidelines advocating for appropriate risk stratification, ambulatory surgery in low-risk patients continues to be accompanied by a battery of routine tests prior to surgery. Using a single-center retrospective cohort study, we aimed to quantify the incidence of un-indicated preoperative testing in an academic ambulatory center by utilizing recommendations by the recently developed American Society of Anesthesiology (ASA) "Choosing Wisely" Top-5 list.

Methods: We utilized data from the EPIC medical records of 3111 patients who had ambulatory surgery at the Hospital of the University of Pennsylvania during a 6-month period. Data were abstracted from laboratory studies- complete blood count, electrolyte panel, coagulation studies, and cardiac studies-stress test, and echocardiogram obtained within 30 days prior to surgery. Preoperative tests obtained from each patient were categorized into "indicated" (ASA ≥ 3) and "un-indicated" (ASA 1 and 2) tests, and percentages were reported.

Results: During the study period, 52.9 % (95 % confidence interval (CI) 37.6-66.4) of all patients had at least one un-indicated laboratory test performed preoperatively. Further analysis revealed variation in the incidence of preoperative ordering between tests; 73 % of all complete blood counts (CBCs), 70 % of all metabolic panels, and 49 % of all coagulation studies were considered un-indicated by "Top-5 List" criteria. Stated differently, of the patients included in the sample, 51 % of patients received an un-indicated CBC, 41 % an un-indicated metabolic panel, and 16 % un-indicated coagulation studies. Twelve percent of "any un-indicated preoperative test" were obtained from ASA 1 healthy patients. Of the 587 patients less than 36 years old, 331 (56 %) had at least one test that was deemed un-indicated. Forty-one patients had either an echocardiogram or stress test ordered and performed within 30 days of surgery. Of these, eight (19.5 %) studies were un-indicated as determined by chart review.

Conclusions: The incidence of ordering "at least one un-indicated preoperative test" in low-risk patients undergoing low-risk surgery remains high even in academic tertiary institutions. In the emerging era of optimizing patient safety and financial accountability, further studies are needed to better understand the problem of overuse while identifying modifiable attitudes and institutional influences on perioperative practices among all stakeholders involved. Such information would drive the development of feasible interventions.