Should I repeat my 1:2s QC rejection?

Area of Science:

• Clinical Chemistry
• Laboratory Quality Control

Background:

• Repeating quality control (QC) samples outside 2 standard deviations (1:2s rule) is a frequent practice.
• Despite its common use, the statistical power of this repeat-sampling approach has not been rigorously evaluated.

Purpose of the Study:

• To mathematically and computationally evaluate the power of 1:2s repeat-sampling strategies.
• To compare the effectiveness of these strategies against established QC rules (1:2s, 1:3s) and common multirules.

Main Methods:

• Power functions were computed using mathematical calculations and computer simulations.
• Four distinct 1:2s repeat-sampling strategies were analyzed.
• Performance was benchmarked against the 1:2s rule, 1:3s rule, and two common QC multirules.

Main Results:

• Repeat-sampling strategies demonstrated low false-rejection rates, similar to the 1:3s QC rule.
• Error detection rates for repeat-sampling approached those of the 1:2s rule for significant errors.
• The power of repeat-sampling strategies generally exceeded that of the evaluated QC multirules, with a 4-13% increase in QC utilization.

Conclusions:

• Repeat-sampling strategies effectively combine the benefits of 1:2s and 1:3s QC rules.
• These strategies offer favorable power compared to common QC multirules.
• The enhanced performance is achieved with a minor increase in the average number of controls tested.