Session Information
Date: Sunday, November 8, 2015
Title: Vasculitis Poster I
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose:
The purpose of this study was to evaluate the contribution of MPO-/PR3-ANCA tests to the diagnosis of ANCA-associated vasculitis (AAV).
Methods:
We extracted patients who underwent MPO-/PR3-ANCA tests during the 5-year period from June 2009 to July 2014 using an electronic medical record system of a general hospital that has Departments of Rheumatology, Nephrology, Respiratory Diseases, Neurology, Cardiology, General Internal Medicine, and Dermatology in Okinawa, Japan. In the extracted patients, the clinical diagnosis and patients’ background were confirmed using this system.
Results:
From June 2009 to July 2014, 2,782 samples obtained from 2,019 subjects were presented to the MPO-ANCA and PR3-ANCA tests (CLEIA method). MPO-ANCA and PR3-ANCA were positive in 107 (5%) and 36 (2%) subjects, respectively, of whom 50 (48.0%) and 3 (8.3%), respectively, had AAV, and 12 (11.2%) and 12 (33.3%), respectively, had infection. In the MPO-ANCA-positive patients, those with AAV showed a significantly higher MPO-ANCA level than the non-AAV patients (p = 0.001). In the PR3-ANCA-positive patients, the PR3-ANCA level did not differ between AAV and non-AAV patients. In this study, the sensitivity, specificity, positive predictive value, and negative predictive value of the MPO-ANCA test in AAV diagnosis were 0.85, 0.69, 0.47, and 0.93, respectively, and those of the PR3-ANCA test were 0.25, 0.79, 0.08, and 0.93, respectively.
Conclusion:
In daily practice in the Department of Rheumatology and the other departments, many samples had been presented for MPO-/PR3-ANCA tests. However, the percentage of patients positive for each test was low (< 10%). In this study, the positive predictive values of both MPO-ANCA and PR3-ANCA tests were low. Most ANCA-positive patients had diseases other than AAV, including many with infection. These results suggest that the results of the ANCA tests in daily practice should be carefully interpreted, and differential diagnosis between AAV and other diseases such as infection is important. The MPO-ANCA level was higher in the AAV group than in the non-AAV group. However, both the MPO-ANCA and PR3-ANCA values markedly varied in each group, and AAV diagnosis based on the ANCA level was difficult. In a previous large-scale study, the sensitivity and specificity of the MPO-ANCA test for MPA were 58 and 91%, respectively, and those of the PR3-ANCA test for GPA were 65-67 and 86-89%, respectively. The low specificity of the MPO-ANCA test based on data in this hospital suggests the presence of many patients with ANCA-negative MPA. In addition, compared with the previous study, the sensitivity and positive predictive value of PR3-ANCA were extremely low. These results may reflect the low prevalence of GPA in Japan.When samples are presented for ANCA tests, patients in whom the pre-test probability of AAV is high should be selected, and the results of the test should be carefully interpreted even when samples are positive.
To cite this abstract in AMA style:
Uechi E, Nakata C, Murayama T, Shiohira Y. Contribution of MPO-/PR3-ANCA Tests to the Diagnosis of ANCA-Associated Vasculitis in a Community Hospital: Evaluation of 2,782 Samples [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/contribution-of-mpo-pr3-anca-tests-to-the-diagnosis-of-anca-associated-vasculitis-in-a-community-hospital-evaluation-of-2782-samples/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/contribution-of-mpo-pr3-anca-tests-to-the-diagnosis-of-anca-associated-vasculitis-in-a-community-hospital-evaluation-of-2782-samples/