＜Editors' Choice＞ Comparison of clinical features between patients with acute exacerbation of idiopathic interstitial pneumonia and collagen vascular disease-associated interstitial pneumonia.

Acute exacerbation (AE) of interstitial pneumonia (IP) shows poor prognosis, due to the typical histological pattern of diffuse alveolar damage superimposed upon lung fibrosis. The previous reports comparing clinical features between AE of idiopathic interstitial pneumonias (IIPs) and those of IPs with known etiology are limited. We retrospectively compared clinical parameters including age, sex, Charlson Comorbidity Index score (CCIS), blood biomarkers at diagnosis of AE, treatment, and 3-month mortality between patients with AE of IIPs and collagen vascular disease-associated interstitial pneumonia (CVD-IP). We assessed 85 patients, comprising 66 patients with AE of IIPs (78%) and 19 patients with AE of CVD-IP (22%). The least absolute shrinkage and selection operator regression selected CCIS (hazard ratio, 1.281; 95% confidence interval, 1.055-1.556; P = 0.012) and log serum lactate dehydrogenase (LDH) (hazard ratio, 6.267; 95% confidence interval, 2.172-18.085; P < 0.001) as significant predictors of 3-month mortality among these patients. Also, the adjusted survival curves using sex, CCIS, and serum LDH showed no significant differences between these two groups. In conclusion, among AE patients, CCIS and serum LDH level may be more important prognostic factors for 3-month mortality rather than two classification of IP subtypes: IIPs and CVD-IP.