Variation in ANA titres in Auckland

Area of Science:

• Immunology
• Clinical Chemistry
• Rheumatology

Background:

• Antinuclear antibody (ANA) testing is crucial for diagnosing autoimmune rheumatic diseases.
• Previous studies indicated significant intralaboratory and interlaboratory variation in ANA titre reporting.

Purpose of the Study:

• To assess current intralaboratory and interlaboratory variation in ANA titre reporting among three Auckland laboratories.
• To compare current findings with a similar study conducted in 1981 to evaluate improvements in ANA test reproducibility.

Main Methods:

• Serum samples from 26 rheumatology patients were analyzed.
• Samples were sent to three Auckland laboratories on two separate days for ANA presence and titre determination.

Main Results:

• Intralaboratory variation decreased, with no differences greater than two titre dilutions observed.
• Interlaboratory correlation improved since the 1981 study, notably between Laboratory A and Laboratory B.

Conclusions:

• The ANA test, when reported as titres, demonstrates enhanced reproducibility in Auckland laboratories compared to historical data.
• Improvements suggest better standardization and consistency in ANA testing procedures over time.