Does routine repeat testing of critical values offer any advantage over single testing?

Area of Science:

• Clinical laboratory science
• Hematology
• Diagnostic accuracy

Background:

• Critical laboratory values require verification before communication to caregivers.
• Repeat testing aims to ensure accuracy and prevent reporting of false or erroneous results.

Purpose of the Study:

• To evaluate if a second testing run offers benefits over a single run for critical laboratory values.
• To assess if repeat testing enhances accuracy or reduces reporting errors.

Main Methods:

• Retrospective collection of over 500 critical values for five hematology tests: hemoglobin, white blood cell count, platelet count, prothrombin time, and activated partial thromboplastin time.
• Calculation and averaging of absolute value and percentage change between two testing runs for each critical value.
• Comparison of results against laboratory-defined acceptable tolerance limits for reruns.

Main Results:

• Mean differences between runs were within acceptable tolerance limits for all tested critical values (e.g., hemoglobin: 0.08 g/dL, 1.4%).
• The percentage of specimens outside acceptable tolerance limits ranged from 0% to 2.2%.
• No false or erroneous critical results were identified between the two testing runs across all categories.

Conclusions:

• Routine repeat testing of critical hemoglobin, platelet, and white blood cell counts, as well as prothrombin time and activated partial thromboplastin time, provides no added advantage over a single testing run.
• Current practices of repeat testing for these critical values may not be necessary for ensuring accuracy.