TY - JOUR T1 - Prevalence and prognosis of unclassifiable interstitial lung disease JF - European Respiratory Journal JO - Eur Respir J SP - 750 LP - 757 DO - 10.1183/09031936.00131912 VL - 42 IS - 3 AU - Christopher J. Ryerson AU - Thomas H. Urbania AU - Luca Richeldi AU - Joshua J. Mooney AU - Joyce S. Lee AU - Kirk D. Jones AU - Brett M. Elicker AU - Laura L. Koth AU - Talmadge E. King, Jr AU - Paul J. Wolters AU - Harold R. Collard Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/3/750.abstract N2 - The aim of this study was to determine the prevalence, characteristics and outcomes of patients with unclassifiable interstitial lung disease (ILD) and to develop a simple method of predicting disease behaviour. Unclassifiable ILD patients were identified from an ongoing longitudinal cohort. Unclassifiable ILD was diagnosed after a multidisciplinary review did not secure a specific ILD diagnosis. Clinical characteristics and outcomes were compared with idiopathic pulmonary fibrosis (IPF) and non-IPF ILDs. Independent predictors of mortality were determined using Cox proportional-hazards analysis to identify subgroups with distinct disease behaviour. Unclassifiable ILD was diagnosed in 10% of the ILD cohort (132 out of 1370 patients). The most common reason for being unclassifiable was missing histopathological assessment due to a high risk of surgical lung biopsy. Demographic and physiological features of unclassifiable ILD were intermediate between IPF and non-IPF disease controls. Unclassifiable ILD had longer survival rates when compared to IPF on adjusted analysis (hazard ratio 0.62, p = 0.04) and similar survival compared to non-IPF ILDs (hazard ratio 1.54, p = 0.12). Independent predictors of survival in unclassifiable ILD included diffusion capacity of the lung for carbon monoxide (p = 0.001) and a radiological fibrosis score (p = 0.02). Unclassifiable ILD represents approximately 10% of ILD cases and has a heterogeneous clinical course, which can be predicted using clinical and radiological variables. Unclassifiable ILD has a heterogeneous clinical course that can be predicted using clinical and radiological variables http://ow.ly/mdjwg ER -