Antinuclear antibody testing: discordance between commercial laboratories

Area of Science:

• Clinical Immunology
• Laboratory Medicine
• Rheumatology

Background:

• Antinuclear antibody (ANA) testing is crucial for patient evaluation, diagnosis, and treatment.
• Discrepancies in ANA test results across different laboratories can complicate clinical management.

Purpose of the Study:

• To assess the agreement level of ANA test results between two commercial laboratories.
• To investigate the clinical implications of inter-laboratory variability in ANA testing.

Main Methods:

• A retrospective chart review of 101 paired ANA tests performed at two commercial laboratories.
• Sensitivity analysis was conducted using four different criteria (A to D) to define agreement.
• Relevant clinical data, including presenting complaints, exam findings, and diagnoses, were collected.

Main Results:

• Agreement between paired ANA tests was low, ranging from 18% (strictest criteria) to 42% (most lenient criteria).
• For patients with ANA-associated rheumatic disease (n=7), none of the paired tests agreed under the strictest criteria.
• Two of seven patients with rheumatic disease showed agreement under the most lenient criteria.

Conclusions:

• Significant variability exists in ANA test results between commercial laboratories.
• The poor agreement raises concerns about the reliability of current ANA testing practices.
• Inter-laboratory differences in ANA testing may have substantial clinical consequences for patient care.