Acute exacerbation of interstitial pneumonia other than idiopathic pulmonary fibrosis

Backgrounds: Acute exacerbation (AE) in idiopathic pulmonary fibrosis (IPF) is increasingly recognized as a relatively common and highly morbid clinical event. However, clinical data on AE in non-IPF interstitial pneumonia are sparse. This study was performed to find the frequency, clinical features, and outcome of AE in non-IPF interstitial pneumonia. Methods: Retrospective analysis of 10 patients who satisfied the modified Akira criteria for AE during follow-up of 74 patients with surgical lung biopsy-confirmed idiopathic nonspecific interstitial pneumonia (I-NSIP) and 93 patients with biopsy-confirmed interstitial pneumonia associated with collagen vascular disease (CVD-IP). Results: AE occurred in six patients with I-NSIP (1-year frequency, 4.2%) and in four patients with CVD-IP (rheumatoid arthritis [RA], n = 3; scleroderma, n = 1), with 1-year frequency of 3.3%. Median age was 58 years (range, 47 to 75); six patients were female. AE occurred in two patients immediately after surgical biopsy. Median duration of acute symptom before hospital admission was 10 days (range, 1 to 30). Median ratio of PaO2 to the fraction of inspired oxygen (FIO2) was 172 (range, 107 to 273), and PaO2/FIO2 ratio was < 200 in six patients. Surgical lung biopsy performed at the time of AE in two patients revealed diffuse alveolar damage superimposed on nonspecific interstitial pneumonia pattern. Four patients with I-NSIP survived to discharge and were followed up for 24 months (range, 6 to 121). Conclusion: AE occurred in the patients with I-NSIP with apparently better prognosis. In patients with CVD-IP, AE occurred mostly with RA-usual interstitial pneumonia in our small series with poor outcome.