Serum galactomannan antigen test for the diagnosis of chronic pulmonary aspergillosis

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Summary

Background

A serum galactomannan (GM) antigen test has been widely used to diagnose invasive pulmonary aspergillosis. However, there are limited data on the use of the serum GM antigen test for the serologic diagnosis of chronic pulmonary aspergillosis (CPA).

Methods

Data were collected from all consecutive patients with a clinical suspicion of CPA who underwent a serum GM antigen test.

Results

In total, 334 patients who were suspected to have CPA were eligible for this study and 168 (50%) patients were finally diagnosed with CPA. The serum GM antigen test was positive in 38 (23%) patients with CPA and in 25 (15%) patients without CPA. The sensitivity of the serum GM antigen test was 23% (95% confidence interval [CI], 17–30%), and its specificity was 85% (95% CI, 79–90%), with positive and negative predictive values of 60% (95% CI, 47–72%) and 52% (95% CI, 46–58%), respectively. The accuracy of the test was 54%. The area under the receiver operating characteristic curve was 0.538 (95% CI, 0.496–0.580).

Conclusion

The serum GM antigen test could not be used for the serologic diagnosis of CPA.

Introduction

The chronic forms of pulmonary aspergillosis are simple aspergilloma, chronic cavitary pulmonary aspergillosis (CCPA), and chronic necrotizing pulmonary aspergillosis (CNPA).1 Although certain authors distinguish chronic fibrosing pulmonary aspergillosis (CFPA) from CCPA,2 many investigators have described CCPA, CFPA, and CNPA as chronic pulmonary aspergillosis (CPA) in the recent literature.3, 4, 5

The diagnosis of CPA is difficult and is generally based on a constellation of clinical signs and symptoms, radiologic manifestations, and microbiological evidence, including the positive isolation of Aspergillus species from respiratory tract samples.6, 7, 8, 9 However, in patients with CPA, the role of conventional culture is limited by low sensitivity and relatively delayed results.10 Therefore, a serum Aspergillus precipitin antibody test has been widely used for the serologic diagnosis of CPA.6, 7, 8, 10

Galactomannan (GM) is a component of the Aspergillus species cell wall and is released into the surrounding environment during fungal growth or tissue invasion.11 A serum GM antigen test has been widely used to diagnose invasive pulmonary aspergillosis.12 However, there are limited data on the use of the serum GM antigen test in patients with CPA.4, 10, 13, 14 Therefore, we investigated the diagnostic performance of the serum GM antigen test to evaluate the utility of the test for the serologic diagnosis of CPA.

Section snippets

Patients and methods

Data were collected from all consecutive patients with a clinical suspicion of CPA who underwent a serum GM antigen test at the Samsung Medical Center (a 1961-bed, university-affiliated, tertiary referral hospital in Seoul, South Korea) between January 2010 and December 2012 and were retrospectively analyzed. A portion of the clinical data from these patients was included in an article published in 2013.9 Immunocompromised patients, such as those with neutropenia, hematological malignancy, or

Results

During the study period, a total of 334 patients who were suspected to have CPA were eligible for this study. The clinical characteristics of the patients are presented in Table 1. Most patients had underlying lung disease, such as previous tuberculosis (n = 254, 76%), bronchiectasis (n = 181, 54%), or nontuberculous mycobacterial lung disease (n = 120, 36%). All patients presented with at least one of the following chest CT findings: cavity (n = 301, 90%), consolidation (n = 214, 64%),

Discussion

In the present study, we evaluated the utility of the serum GM antigen test for the diagnosis of CPA using a relatively large number of patients who were suspected to have CPA. However, the diagnostic performance of the serum GM antigen test was not acceptable for use in clinical practice due to low accuracy and discriminatory power.

The serum GM antigen test was originally studied and approved for use in the diagnosis of invasive aspergillosis.12 Recently, this test was evaluated as a method to

Conflict of interest statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Acknowledgments

This work was supported by a Samsung Biomedical Research Institute grant (SBRI C-B1-101).

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c

Beomsu Shin and Won-Jung Koh contributed equally to this work.

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