PT  - JOURNAL ARTICLE
AU  - Chen, Der-Yuan
AU  - Huang, Yen-Hsiang
AU  - Chen, Yi-Ming
AU  - Chen, Jeremy J W
AU  - Yang, Tsung-Ying
AU  - Chang, Gee-Chen
AU  - Tang, Kuo-Tung
TI  - ANA positivity and complement level in pleural fluid are potential diagnostic markers in discriminating lupus pleuritis from pleural effusion of other aetiologies
AID  - 10.1136/lupus-2021-000562
DP  - 2021 Nov 01
TA  - Lupus Science & Medicine
PG  - e000562
VI  - 8
IP  - 1
4099  - http://lupus.bmj.com/content/8/1/e000562.short
4100  - http://lupus.bmj.com/content/8/1/e000562.full
SO  - Lupus Sci Med2021 Nov 01; 8
AB  - Objective Lupus pleuritis is the most common pulmonary manifestation of systemic lupus erythematosus (SLE). We aimed to compare various biomarkers in discriminating between pleural effusions due to lupus pleuritis and other aetiologies.Methods We determined in 59 patients (16 patients with SLE and 43 patients without SLE) pleural fluid levels of high-mobility group box 1, soluble receptor for advanced glycation end products (sRAGE), adenosine deaminase (ADA), interleukin (IL) 17A, tumour necrosis factor-α, antinuclear antibodies (ANA), and complements C3 and C4.Results We found significant differences in the pleural fluid level of sRAGE, ADA, IL-17A, C3 and C4, and in the proportion of ANA positivity, among lupus pleuritis and other groups with pleural effusion. Specifically, ANA positivity (titre ≥1: 80) achieved a high sensitivity of 91%, specificity of 83% and negative predictive value (NPV) of 97% in discriminating lupus pleuritis from non-lupus pleural effusion. A parallel combination of the level of C3 (<24 mg/dL) and C4 (<3 mg/dL) achieved a sensitivity of 82%, specificity of 89% and NPV of 93% in discriminating lupus pleuritis from non-lupus exudative pleural effusion.Conclusions In conclusion, ANA, C3 and C4 in pleural fluid are useful in discriminating lupus pleuritis from pleural effusion due to other aetiologies with high NPV.Data are available upon reasonable request. Data are available from the corresponding author upon reasonable request.