Diagnostic performance of measuring antibodies to the glycopeptidolipid core antigen specific to Mycobacterium avium complex in patients with rheumatoid arthritis: results from a cross-sectional observational study

Systematic review for the treatment of older rheumatoid arthritis patients informing the 2024 update of the Japan College of Rheumatology clinical practice guidelines for the management of rheumatoid arthritis

OBJECTIVES

To update an evidence base informing the 2024 Japan College of Rheumatology clinical practice guidelines for the management of rheumatoid arthritis (RA) in older adults.

METHODS

Four clinical questions (CQs) regarding efficacy and safety of drug treatment were evaluated, with CQ1 addressing methotrexate (MTX), CQ2 biological disease-modifying antirheumatic drugs, CQ3 Janus kinase (JAK) inhibitors, and CQ4 glucocorticoids (GCs). Quality of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation system.

RESULTS

Observational studies confirmed a pivotal role of methotrexate in the treatment of older RA patients. The meta-analysis showed that tumour necrosis factor inhibitors and JAK inhibitors were unequivocally effective in older RA patients. No data indicated that biological disease-modifying antirheumatic drugs were unsafe for older patients. No safety data for JAK inhibitor use in older patients were available. One randomized controlled trial demonstrated that long-term treatment with low-dose GCs increased risks of GC-associated adverse events. The certainty of overall evidence was very low for all CQs.

CONCLUSIONS

This systematic review provides the necessary evidence for developing 2024 Japan College of Rheumatology clinical practice guidelines for managing older patients with RA. Continued updates on the evidence of JAK inhibitors and GC are desired.

Diagnosis and Management of Pulmonary NTM with a Focus on Mycobacterium avium Complex and Mycobacterium abscessus: Challenges and Prospects

BACKGROUND

Nontuberculous mycobacteria (NTM) are ubiquitous. NTM can affect different organs and may cause disseminated diseases, but the pulmonary form is the most common form. Pulmonary NTM is commonly seen in patients with underlying diseases. Pulmonary Mycobacterium avium complex (MAC) is the most common NTM disease and M. abscessus (MAB) is the most challenging to treat. This review is prepared with the following objectives: (a) to evaluate new methods available for the diagnosis of pulmonary MAC or MAB, (b) to assess advances in developing new therapeutics and their impact on treatment of pulmonary MAC or MAB, and (c) to evaluate the prospects of preventive strategies including vaccines against pulmonary MAC or MAB.

METHODS

A literature search was conducted using PubMed/MEDLINE and multiple search terms. The search was restricted to the English language and human studies. The database query resulted in a total of 197 publications. After the title and abstract review, 64 articles were included in this analysis.

RESULTS

The guidelines by the American Thoracic Society (ATS), European Respiratory Society (ERS), European Society of Clinical Microbiology and Infectious Diseases (ESCMID), and Infectious Diseases Society of America (IDSA) are widely applicable. The guidelines are based on expert opinion and there may be a need to broaden criteria to include those with underlying lung diseases who may not fulfill some of the criteria as 'probable cases' for better follow up and management. Some cases with only one culture-positive sputum sample or suggestive histology without a positive culture may benefit from new methods of confirming NTM infection. Amikacin liposomal inhalation suspension (ALIS), gallium containing compounds and immunotherapies will have potential in the management of pulmonary MAC and MAB.

CONCLUSIONS

the prevalence of pulmonary NTM is increasing. The efforts to optimize diagnosis and treatment of pulmonary NTM are encouraging. There is still a need to develop new diagnostics and therapeutics.

Serological diagnosis of Mycobacterium avium complex lung diseases by enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen

Introduction

There is an increasing trend worldwide in the incidence of Mycobacterium avium complex pulmonary diseases (MAC-PD) and the diagnosis is sometimes complicated. Recently, an enzyme immunoassay (EIA) kit that detects serum IgA antibody against MAC-specific glycopeptidolipid (GPL) core antigen had been developed and found to be useful in discriminating MAC-PD from other lung diseases. The antibody was subsequently also found to be elevated in patients suffering Mycobacterium abscessus pulmonary diseases (MAB-PD). This study is to evaluate this EIA kit in the serological diagnosis of MAC-PD in Hong Kong Chinese patients.

Methods

The study was conducted in Grantham Hospital, Hong Kong between July 2017 and July 2018. Assay of the IgA antibody level using the EIA kit was done on blood samples collected from patients suffering from MAC-PD, MAB-PD, pulmonary tuberculosis and other lung diseases.

Results

There were 100 subjects recruited into the study, among which 11 were excluded. By using the cut-off value 0.7 U/mL provided by the manufacturer, the sensitivity and specificity for diagnosis were 73.7% and 77.6% for MAC-PD; 50% and 77.6% for MAB-PD. By receiver operating characteristic curves analysis, new cut-off for MAC-PD and MAB-PD were calculated as 1.771 U/mL and 0.172 U/m, respectively. The sensitivity and specificity were 68.4% and 86.2% for MAC-PD, whereas 66.7% and 72.4% for MAB-PD.

Conclusions

Our study showed that the enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen could help to distinguishing MAC and M. abscessus pulmonary diseases from pulmonary tuberculosis and other lung diseases among Hong Kong Chinese patients. Further larger scale studies in our local population for the usefulness of this antibody test in the diagnosis and monitoring of MAC and M. abscessus lung diseases might be warranted.

Application of a commercial serodiagnostic kit that measures the serum anti-glycopeptidolipid core IgA antibody in Mycobacterium avium complex pulmonary disease

The diagnosis of Mycobacterium avium complex (MAC) pulmonary disease is occasionally cumbersome and time-consuming because the MAC species is ubiquitous, and therefore its detection is not necessarily indicative of a definitive diagnosis. A serodiagnostic method specific for MAC pulmonary disease that measures the serum anti-glycopeptidolipid core antigen IgA has been developed and is commercially available. Meta-analysis revealed that the test showed a good diagnostic accuracy. The estimated sensitivity and specificity values were 69.6% (95% confidence interval 62.1-76.1) and 90.6% (95% confidence interval 83.6-95.1), respectively. As antibody levels may reflect the disease activity, their serial measurement can also be used in the management of MAC disease. To justify its routine use in clinical practice, further validation in various regions and studies addressing whether serodiagnosis combined with present diagnostic criteria facilitate more rapid accurate diagnosis of MAC pulmonary disease are necessary.

Levels of Antibody against Glycopeptidolipid Core as a Marker for Monitoring Treatment Response in Mycobacterium avium Complex Pulmonary Disease: a Prospective Cohort Study

The diagnosis of Mycobacterium avium complex pulmonary disease (MAC-PD) is sometimes complicated and time-consuming. A serodiagnostic kit that measures the serum levels of IgA antibodies against the glycopeptidolipid (GPL) core is commercially available and has good diagnostic accuracy for MAC-PD. However, the significance of measurement of GPL core IgA antibody levels in monitoring for chemotherapy response in patients with MAC-PD was not well investigated. Thirty-four treatment naive MAC-PD patients who were started on multidrug chemotherapy were enrolled. Their antibody levels were prospectively measured at regular intervals. The relationships between their antibody levels and the therapeutic outcomes were examined. The patients were classified into three groups (conversion, recurrence, and nonconversion) based on the bacteriological outcomes after chemotherapy. There were no significant differences in the antibody levels before treatment between the culture conversion (n = 19), recurrence (n = 7), and nonconversion (n = 8) groups (P = 0.9881). The levels decreased significantly after the chemotherapy (P < 0.0001). Recurrence and/or worsening of chest radiography findings were observed in cases whose antibody levels subsequently increased after cessation of the chemotherapy. No significant difference in the percent decrease in antibody levels by the chemotherapy was observed between the culture conversion and recurrence groups (P = 0.9338). The initial antibody levels are not a predictor of therapeutic outcomes, and also the percent decrease in antibody levels is not a sufficient indicator of the cessation of chemotherapy. However, serial measurements of antibody levels may allow objective monitoring of disease activity in individual MAC-PD patients.

Diagnostic test accuracy of anti-glycopeptidolipid-core IgA antibodies for Mycobacterium avium complex pulmonary disease: systematic review and meta-analysis

Currently, an anti-glycopeptidolipid (GPL)-core IgA antibody assay kit for diagnosing Mycobacterium avium complex (MAC) is commercially available. We conducted this systematic review and meta-analysis to reveal the precise diagnostic accuracy of anti-GPL-core IgA antibodies for MAC pulmonary disease (MAC-PD). We systematically searched reports that could provide data for both sensitivity and specificity by anti-GPL-core IgA antibody for clinically diagnosed MAC-PD. Diagnostic test accuracy was estimated using the bivariate model. Of the 257 articles that we had found through primary search, we finally included 16 reports consisted of 1098 reference positive subjects and 2270 reference negative subjects. The diagnostic odds ratio was 24.8 (95% CI 11.6–52.8, I² = 5.5%) and the area under the hierarchical summary receiver operating characteristic curves was 0.873 (95% CI 0.837–0.913). With a cutoff value of 0.7 U/mL, the summary estimates of sensitivity and specificity were 0.696 (95% CI 0.621–0.761) and 0.906 (95% CI 0.836–0.951), respectively. The positive and negative likelihood ratios were 7.4 (95% CI 4.1–13.8) and 0.34 (95% CI 0.26–0.43), respectively. The demanding clinical diagnostic criteria may be a cause of false positive of the index test. The index test had good overall diagnostic accuracy and was useful to ruling in MAC-PD with the cutoff value.