Comparison of coccidioidal complement fixation and quantitative immunodiffusion serology at a reference laboratory

Area of Science:

• Medical Mycology
• Clinical Diagnostics
• Immunoserology

Background:

• Coccidioidomycosis incidence is rising, necessitating reliable diagnostic methods.
• Current non-invasive diagnostics include immunodiffusion and complement fixation (CF) testing.
• Complement fixation (CF) testing is considered the gold standard for coccidioidomycosis diagnosis.

Purpose of the Study:

• To directly compare quantitative immunodiffusion and complement fixation (CF) testing for IgG antibodies.
• To assess the concordance between immunodiffusion and CF tests in diagnosing coccidioidomycosis.
• To determine the interchangeability of these diagnostic methods in a reference laboratory.

Main Methods:

• Comparative analysis of 368 patient samples.
• Quantitative immunodiffusion assay for IgG antibodies.
• Complement fixation (CF) assay for IgG antibodies.

Main Results:

• A high concordance rate of 97.8% (360/368 samples) was observed between the two methods.
• Statistical analysis showed a P-value < .001, indicating a highly significant agreement.
• Both immunodiffusion and CF tests demonstrated strong agreement in detecting IgG antibodies.

Conclusions:

• Quantitative immunodiffusion and complement fixation (CF) testing for IgG antibodies are highly concordant.
• These diagnostic tests can be considered interchangeable in reference laboratory settings for coccidioidomycosis.
• The findings support the use of either method for reliable coccidioidomycosis diagnosis.