Laboratory Stewardship and Repetitive Testing: Effect of a Minimum Retest Interval Alert at Order Entry

Abstract

Repeat ordering of a laboratory test before a clinically meaningful change could plausibly have occurred -- a recognised, wasteful
pattern sometimes called repetitive testing -- persists at most hospitals despite widespread awareness of it as a stewardship target.
We implemented a minimum retest interval alert at order entry across twenty-two chemistry and haematology analytes, firing
when a repeat order fell inside an analyte-specific interval with no override reason recorded, and measured its effect on
repeat-order volume over twelve months against a twelve-month pre-implementation baseline. Repeat orders inside the minimum
interval fell by 34.6% overall, with the largest reductions in analytes ordered as part of routine daily panels rather than in
response to an acute clinical change, and clinicians overrode the alert with a documented reason in 11.2% of firings, most
commonly citing a genuine acute change in the patient's condition. We report the alert design, the interval table by analyte, and
the override pattern as a practical account of what a minimum retest interval intervention changes and what it does not.