Abstract
BackgroundMyeloperoxidase anti-neutrophil cytoplasmic antibody-related nephritis (MPO-ANCA nephritis) is occasionally accompanied by lung abnormalities such as pulmonary fibrosis. However, the clinical features of pulmonary fibrosis in patients with MPO-ANCA nephritis have not been well documented. This study was performed to compare the prognosis of a usual interstitial pneumonia (UIP) pattern of lung fibrosis in patients with MPO-ANCA nephritis with the prognosis of idiopathic pulmonary fibrosis (IPF).MethodsWe retrospectively reviewed the medical records of 126 patients with MPO-ANCA nephritis and identified 31 with a UIP pattern of lung fibrosis on high-resolution or thin-slice computed tomography (CT). We compared the characteristics and prognosis of these patients with those of 32 patients with IPF. In 18 patients from both groups, we assessed and compared the decline in lung volume over time using three-dimensional (3D) CT images reconstructed from thin-section CT data.ResultsThe numbers of male and female patients were nearly equal among patients with MPO-ANCA nephritis exhibiting a UIP pattern; in contrast, significant male dominancy was observed among patients with IPF (p = 0.0021). Significantly fewer smokers were present among the patients with MPO-ANCA nephritis with a UIP pattern than among those with IPF (p = 0.0062). There was no significant difference in the median survival time between patients with MPO-ANCA nephritis with a UIP pattern (50.8 months) and IPF (55.8 months; p = 0.65). All patients with IPF in this cohort received antifibrotic therapy (pirfenidone or nintedanib). Almost half of the deaths that occurred in patients with MPO-ANCA nephritis with a UIP pattern were caused by non-respiratory-related events, whereas most deaths in patients with IPF were caused by respiratory failure such as acute exacerbation. In the 3D CT lung volume analyses, the rate of decline in lung volume was equivalent in both groups.ConclusionsMPO-ANCA nephritis with a UIP pattern on CT may have an unfavorable prognosis equivalent to that of IPF with a UIP pattern treated with antifibrotic agents.
Highlights
Myeloperoxidase anti-neutrophil cytoplasmic antibody-related nephritis (MPO-Anti-neutrophil cytoplasmic antibody (ANCA) nephritis) is occasionally accompanied by lung abnormalities such as pulmonary fibrosis
MPO-ANCA nephritis with a usual interstitial pneumonia (UIP) pattern on computed tomography (CT) may have an unfavorable prognosis equivalent to that of idiopathic pulmonary fibrosis (IPF) with a UIP pattern treated with antifibrotic agents
Our study showed that MPO-ANCA nephritis with a UIP pattern might have a poor prognosis similar to that of IPF under the appropriate therapy for each type of disease
Summary
Myeloperoxidase anti-neutrophil cytoplasmic antibody-related nephritis (MPO-ANCA nephritis) is occasionally accompanied by lung abnormalities such as pulmonary fibrosis. MPOANCA-associated vasculitis more frequently occurs in Japanese patients, whereas proteinase-3 ANCA-associated vasculitis is more common in Europe and the United States [7] Because both glomerulonephritis and pulmonary fibrosis are known to be unfavorable prognostic factors in patients with AAV, management of pulmonary fibrosis in patients with MPO-ANCA-related nephritis (MPO-ANCA nephritis) is a critical clinical problem [8, 9]. Some previous studies have addressed the relationship between MPO-ANCA and pulmonary fibrosis, showing that MPO-ANCA positivity is associated with a poor prognosis of pulmonary fibrosis [10] Because these studies focused mainly on pulmonary fibrosis, they may have included patients whose vasculitis activities were indolent or silent. The detailed clinical features of pulmonary fibrosis in patients with overt ANCA-related pathological conditions (i.e., those affecting other organs such as the kidney) have not been fully elucidated
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