A modified quality control protocol for infectious disease serology based on the Westgard rules

Area of Science:

• Clinical Laboratory Science
• Immunology
• Statistical Quality Control

Background:

• Traditional statistical quality control (SQC) protocols, such as the Westgard protocol, face challenges in infectious disease serology due to high false rejection probabilities.
• Assessing the probability of false rejection (Pfr) and error detection (Ped) is crucial for evaluating SQC performance in this field.

Purpose of the Study:

• To evaluate the Pfr of existing SQC protocols (Westgard and Rilibak) in infectious disease serology.
• To develop and verify an improved asymmetric SQC protocol with reduced Pfr and acceptable Ped.

Main Methods:

• Collected 6 months of quality control (QC) data to evaluate Pfr for Westgard and Rilibak protocols.
• Developed an asymmetric protocol with distinct rules for negative and positive QC data and reset QC means upon reagent lot changes.
• Synchronously tested QC materials and Standard Reference Materials over 6 months to validate the asymmetric protocol's Pfr and Ped.

Main Results:

• The Westgard protocol exhibited a higher rejection rate, particularly after reagent lot changes, with Pfr below the lower control limit (LCL) being significantly higher than above the upper control limit (UCL).
• False rejections were more prevalent in negative QC data, contributing to a Pfr-total of 27-65%.
• The developed asymmetric protocol significantly reduced the proportion of analytes with Pfr by over 20%.

Conclusions:

• Excessive Pfr in infectious disease serology is influenced by systematic errors (reagent lot changes) and random errors (routine QC data variation).
• An asymmetric QC protocol, employing different control limits for negative and positive QC data, effectively reduces Pfr.
• This approach enhances the reliability of serological testing by minimizing unnecessary rejections.