Prognosis and Treatment of Myositis-Associated Severe Interstitial Lung Disease: A Descriptive Study Using a Nationwide Inpatient Database in Japan.

Abstract

The aim of this study was to determine the prognosis, clinical course, and current management of severe interstitial lung disease (ILD) associated with myositis in Japan. We conducted a retrospective descriptive study using a nationwide database for inpatient care of acute illness in Japan. Among a total of ~66 million inpatient admissions, we identified patients with severe ILD associated with polymyositis (PM) or dermatomyositis (DM) who required mechanical ventilation and methylprednisolone pulse therapy (≥1 gm/day of methylprednisolone) from July 2010 to March 2018. We identified 155 patients with PM and 394 with DM who fulfilled the above criteria. The median age of patients was 65 years; DM patients were significantly younger than PM patients (64 versus 68 years; P < 0.001). The numbers of patients who were treated with calcineurin inhibitors, intravenous cyclophosphamide, and polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) were 403 (73.4%), 318 (57.9%), and 78 (14.2%), respectively. All these treatments were given significantly more frequently to the patients with DM compared with those with PM. The uses of other treatment options were much less frequent. The median periods after hospitalization when methylprednisolone pulse therapy, calcineurin inhibitors, mechanical ventilation, intravenous cyclophosphamide, and PMX-DHP were initiated and in-hospital death occurred among patients with DM were 2, 4, 7, 8, 17, and 36 days, respectively. In-hospital mortality was significantly higher in patients with DM than in those with PM (76.6% versus 56.8%; P < 0.001). The mortality of patients with myositis-associated severe ILD who require mechanical ventilation is extremely high despite aggressive and prompt interventions.