Test Utilization Proposal for Reflex Bilirubin Testing: Why Order Two Tests When One Will Do?

Background: Reflex testing algorithms are effective tools to reduce unnecessary laboratory testing. Direct (conjugated) bilirubin (DB) and total bilirubin (TB) are often ordered together at our institution. Therefore, the objective of our study was to evaluate the potential impact of performing reflex testing for DB when TB is elevated.

Methods: We performed a retrospective review of test orders (patients ≥18 years of age) for DB, TB, or for both DB and TB on the same accession number received in our stat laboratory from January through April 2017. The orders were binned into 4 categories depending on the results from each individual test: (a) DB normal and TB normal, (b) DB normal and TB high, (c) DB high and TB normal, and (d) DB high and TB high. The percentage of orders and median (range) test result for each category was calculated.

Results: During the months evaluated, a total of 4828 stat orders were placed for DB, TB, or both DB and TB. A total of 4296 stat orders (89%) were placed with both DB and TB on the same accession number for 4158 unique patients. Of those orders, the vast majority of tests (87.3%) contained normal results for both analytes; only 12.7% of orders contained ≥1 abnormal result.

Conclusions: The majority of all bilirubin tests ordered stat for emergency department and hospitalized patients have values within the reference interval. Consequently, if reflex testing were executed on elevated TB, a large number of DB tests could be avoided.