Objective

Although a possible association among myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA), microscopic polyangiitis (MPA), and idiopathic pulmonary fibrosis (IPF) has been suggested, the clinical significance of MPO-ANCA in idiopathic interstitial pneumonias (IIPs), including IPF and non-IPF, remains unclear. We aimed to investigate the frequency of MPO-ANCA positivity, as well as MPA incidence and risk factors for development in patients initially diagnosed with IIP.

Methods

We retrospectively analysed 305 consecutive patients who were initially diagnosed as IIP and had MPO-ANCA results available.

Results

Of the 305 patients, 26 (8.5%) were MPO-ANCA-positive. Baseline characteristics were similar between the MPO-ANCA-positive and -negative patients. The cumulative 5-year MPA incidence was 24.3% in the MPO-ANCA-positive patients and 0% in the -negative patients (P < 0.0001). MPO-ANCA was positive in 15 of 133 (11.3%) patients initially diagnosed with IPF and in 11 of 172 (6.3%) patients initially diagnosed with non-IPF (P = 0.56), with cumulative 5-year MPA incidence of 6.2% and 1.0%, respectively (P = 0.10). Multivariate analysis revealed that UIP pattern on HRCT (HR = 3.20, P < 0.01) and no treatment for IIP (HR = 3.52, P < 0.01) were independently associated with MPA development in MPO-ANCA-positive patients.

Conclusion

MPO-ANCA positivity was uncommon, but was associated with subsequent MPA development in patients initially diagnosed with IIP, including both IPF and non-IPF cases. The study suggested that attention should be paid to MPA development in MPO-ANCA-positive IIP patients with UIP pattern on HRCT and those without treatment for IIP.

中文翻译：

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髓过氧化物酶抗中性粒细胞胞浆抗体在特发性间质性肺炎中的临床意义

客观的

尽管已提出了髓过氧化物酶抗中性粒细胞胞浆抗体（MPO-ANCA），显微多血管炎（MPA）和特发性肺纤维化（IPF）之间的可能关联，但MPO-ANCA在特发性间质性肺炎（IIP）中的临床意义，包括IPF和非IPF，仍不清楚。我们旨在调查最初诊断为IIP的患者MPO-ANCA阳性的频率，以及MPA发生率和发展的危险因素。

方法

我们回顾性分析了305例最初被诊断为IIP并具有MPO-ANCA结果的连续患者。

结果

在305位患者中，有26位（8.5％）的MPO-ANCA阳性。MPO-ANCA阳性和阴性患者的基线特征相似。MPO-ANCA阳性患者的5年累积MPA发生率为24.3％，阴性患者为0％（P <0.0001）。最初诊断为IPF的133名患者中有15名（11.3％）和最初诊断为非IPF的172名（11％）患者中有11名MPO-ANCA阳性（P = 0.56），累计5年MPA发生率为6.2％和1.0％（P = 0.10）。多因素分析显示，HRCT的UIP模式（HR = 3.20，P <0.01），未治疗IIP（HR = 3.52，P） <0.01）与MPO-ANCA阳性患者的MPA发生独立相关。

结论

MPO-ANCA阳性并不常见，但与最初诊断为IIP的患者（包括IPF和非IPF病例）的随后MPA形成有关。研究表明，应重视在HRCT上有UIP模式且未经IIP治疗的MPO-ANCA阳性IIP患者中MPA的发展。