Agreement between Platelia Aspergillus Ag and Aspergillus Galactomannan Ag VirClia Monotest for detection of galactomannan in serum and bronchoalveolar lavage

Author:

Kauser Jabeen (PK)

Abstract:

Background:
Galactomannan detection in serum or bronchoalveolar lavage (BAL) is a valuable tool for invasive aspergillosis diagnosis along with relevant host and radiological criteria. Platelia Aspergillus Ag (Bio-Rad) test has been used for past several years globally. Recently, Aspergillus galactomannan Ag VirClia monotest (Vircell) has been introduced and seems promising due to its single test automated format with a shorter turnaround time.
Objectives:
To evaluate agreement of Platelia Aspergillus Ag and Aspergillus Galactomannan Ag VirClia Monotest for galactomannan detection in both serum and BAL.
Methods:
The study was conducted at the Aga Khan University Hospital laboratory, Karachi, Pakistan from March-August 2023. Specimens were sent by physicians for galactomannan testing and were first tested using Platelia Aspergillus Ag (Bio-Rad) as per manufacturers recommendations. All positive and a proportion of negative samples were then stored at −80°C. Only a single sample per patient was evaluated. The stored samples were retested within 1-2 weeks using Aspergillus Galactomannan Ag VirClia Monotest (Vircell) according to the manufacturer’s recommendations. The results between methods were compared through Cohen’s kappa coefficient (к). Results were interpreted as: Kappa < 0: No agreement, Kappa between 0.00 and 0.20: Slight agreement, Kappa between 0.21 and 0.40: Fair agreement, Kappa between 0.41 and 0.60: Moderate agreement, Kappa between 0.61 and 0.80: Substantial agreement and Kappa between 0.81 and 1.00: Almost perfect agreement. Results: A total of 69 samples (55 serum and 14 BAL) were evaluated. 18 samples were positive with Platelia Aspergillus and 10 samples were positive with VirClia Monotest. Overall, concordant results were seen in 59 samples (85.5%) (Kappa= 0.681, SE of kappa = 0.088, 95% CI; 0.508-0.855) showing substantial agreement. All negative results with Platelia Aspergillus Ag were found to be negative with VirClia Monotest 41/41 (100%). Of the positive samples reported with Platelia Aspergillus Ag, concordant results were seen in 18/28 (64.3%) by VirClia Monotest. Ten positive samples (6 serum and 4 BAL) were discordant (6 negative and 4 equivocal) by VirClia Monotest. Conclusions: Although a substantial agreement was seen between both tests, but high proportion of positive results reported negative by VirClia Monotest is concerning and need further evaluation.

Abstract Number: 28

Conference Year: 2024

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