Background/Purpose

Many patients with interstitial lung disease (ILD) complicated by microscopic polyangiitis (MPA) show a UIP pattern on chest CT. The prognosis is poorer than that of ILD-free MPA(1). However, the details remain to be clarified.

To investigate the prognosis of pulmonary fibrosis with microscopic polyangiitis (MPA-ILD) and prognostic factors.

Methods

Of patients with MPA who were admitted to our hospital between 2001 and 2013 based on the EMEA classification in 2007, the subjects were MPO-ANCA-positive patients with ILD on HRCT. Using the clinical data and fibrosis score on HRCT(2), we examined prognostic factors.

Results

There were 42 patients with MPA-ILD, consisting of 20 males and 22 females, with a median age (interquartile range) of 73 years (range: 69-76 years). The MPO-ANCA, KL-6, Aa-DO2, %FVC, %DLco/VA, and RV/TLC values at the start of treatment were 189 (52-459) EU, 446 (261-615) U/mL, 25.7 (12-34), 81.3 (69-95)%, 61.4 (45-71)%, and 41.1 (33-50)%, respectively. Concerning HRCT images, 30 patients showed a UIP pattern, and 12 showed a non-UIP pattern. PSL was administered to 41 patients. In 37, it was combined with immunosuppressive drugs (CY was used in 16). In 8, apheresis was performed. In 37 patients, the MPO-ANCA level was maintained below the detection limit.

With respect to the prognosis, 8 patients died (exacerbation of interstitial pneumonia: 2, infection and alveolar hemorrhage: 2, pulmonary hypertension: 1, sudden death: 2, and renal failure: 1). The 5- and 10-year survival rates after the start of treatment were 81.6 and 68.0%, respectively.

Univariate analysis using Cox’s proportional hazard model showed that prognostic factors for lung disease-associated death included the HRCT score (p<0.001), CPFE (p=0.025), and administration of CY (p=0.041). However, on multivariate analysis of these factors, the HRCT score was significantly correlated (p=0.006).

Conclusion

Treatment for MPA-ILD was continued, and the prognosis was more favorable than previously reported. Marked fibrosis and CPFE at the start of treatment were considered to be prognostic factors for lung disease-associated death. Immunosuppressive therapy early after onset may improve the prognosis of MPA-ILD.

reference

(1) Fernandez Casares M, Gonzalez A, Fielli M. Microscopic polyangiitis associated with pulmonary fibrosis. Clin Rheumatol. 2014; May 27.[Epub ahead of print] 

(2) Wells AU, Hansell DM, Rubens MB. Fibrosing alveolitis in systemic sclerosis: indices of lung function in relation to extent of disease on computed tomography. Arthritis Rheum. 1997; 40: 1229-36.

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