Harmonization of ANA testing challenge: quantification strategy to accurately predict end-point titers avoiding...

Area of Science:

• Immunology
• Clinical Chemistry
• Laboratory Medicine

Background:

• Automated antinuclear antibody (ANA) analysis offers advantages, but predicting end-point titers without serial dilutions remains a challenge.
• Current methods for ANA titer determination often involve time-consuming serial dilutions, impacting laboratory efficiency.

Purpose of the Study:

• To develop and validate a conversion table correlating fluorescence signal intensity (FI) values with ANA end-point titers.
• To establish a method for predicting ANA titers from a single sample dilution, avoiding traditional serial dilutions.

Main Methods:

• Eight hundred ninety-four serum samples were analyzed for ANA using the Image Navigator System.
• Statistical discriminant analysis was employed to classify FI into ranges corresponding to conventional end-point titers.
• A validation study assessed agreement and error rates between visual readings and the conversion table for 1119 ANA-positive samples.

Main Results:

• A conversion table was computed, establishing FI ranges for end-point titers across different staining patterns.
• Overall agreement between the conversion table and visual readings was 98.4% for single-pattern samples (titers 1:160-1:2560).
• Concordance rates were high for nuclear (98.4%) and cytoplasmic (100%) patterns, with slightly lower rates for mitotic patterns (66.6%).

Conclusions:

• A novel quantification method for autoantibody titer assessment was developed, utilizing a single sample dilution.
• This method offers significant advantages for routine laboratories, including reduced hands-on time and improved result harmonization.
• The developed tool effectively predicts ANA end-point titers, enhancing efficiency in automated ANA analysis.