Higher frequency of false‐positive serum galactomannan tests among older subjects and the association with elevated serum immunoglobulin G levels
Yoshiaki Abe  Kentaro Narita  Hiroki Kobayashi  Akihiro Kitadate  Masami Takeuchi  Kosei Matsue
First published: 05 June 2019 https://doi.org/10.1111/myc.12951
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/myc.12951
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Abstract
Background
The incidence of false‐positive serum galactomannan (GM) enzyme‐linked immunosorbent assay test results has been scarcely examined among older subjects. Additionally, previous studies have highlighted the influence of serum immunoglobulin G (IgG) levels on GM test results. We hypothesised that age‐related IgG level elevation might also be associated with false‐positive GM test results in older subjects.

Objectives
This study aimed to examine the association between false‐positive GM test results and age or serum IgG levels.

Patients/Methods
We investigated the association between false‐positive serum GM test results and age in 1071 healthy adult subjects. Then, we validated this association and further explored the correlation with serum IgG levels by retrospectively identifying 700 patients with newly diagnosed haematologic disorders without probable or proven invasive aspergillosis.

Results
Healthy subjects with false‐positive GM test results were significantly older than those without false‐positive results (P < 0.001). Among patients with haematologic disorders, IgG myeloma patients showed significantly higher false‐positive rates (57/125 [45.6%]) than patients with other haematologic disorders (malignant lymphoma: 48/315 [15.2%], myelodysplastic syndrome/aplastic anaemia: 19/141 [13.5%]; both P < 0.001) or other types of myeloma (IgA myeloma: 13/60 [21.7%], light chain myeloma: 9/52 [17.3%]; both P < 0.01). Furthermore, among non‐multiple myeloma patients, advanced age and higher IgG level were also significantly associated with the high frequency of false‐positive GM test results.

Conclusions
False‐positive serum GM test results were frequent among older subjects and patients with elevated serum IgG levels. These results suggested that age‐ and/or disease‐related IgG level elevation could induce this phenomenon.