Clinical and Functional Characteristics of Patients with Unclassifiable Interstitial Lung Disease (uILD): Long-Term Follow-Up Data from European IPF Registry (eurIPFreg)

Abstract

: (1) Aim of the study: In spite of extensive research, up to 20% of interstitial lung diseases (ILD) patients cannot be safely classified. We analyzed clinical features, progression factors, and outcomes of unclassifiable ILD (uILD). (2) Methods: A total of 140 uILD subjects from the University of Giessen and Marburg Lung Center (UGMLC) were recruited between 11/2009 and 01/2019 into the European Registry for idiopathic pulmonary fibrosis (eurIPFreg) and followed until 01/2020. The diagnosis of uILD was applied only when a conclusive diagnosis could not be reached with certainty. (3) Results: In 46.4% of the patients, the uILD diagnosis was due to conflicting clinical, radiological, and pathological data. By applying the diagnostic criteria of usual interstitial pneumonia (UIP) based on computed tomography (CT), published by the Fleischner Society, 22.2% of the patients displayed a typical UIP pattern. We also showed that forced vital capacity (FVC) at baseline (p = 0.008), annual FVC decline ≥10% (p < 0.0001), smoking (p = 0.033), and a diffusing capacity of the lung for carbon monoxide (DLco) ≤55% of predicted value at baseline (p < 0.0001) were significantly associated with progressive disease. (4) Conclusions: The most important prognostic factors in uILD are baseline level and decline in lung function and smoking. The use of Fleischner diagnostic criteria allows further differentiation and accurate diagnosis.

Integration of transbronchial cryobiopsy into multidisciplinary board decision: a single center analysis of one hundred consecutive patients with interstitial lung disease

“…After final diagnostic procedures and MDTD, 16% of our patients remained non-classifiable (Fig. 1 B), which is consistent with the literature [ 8 ].…”

Comorbidities in Unclassifiable Interstitial Lung Disease

“…A larger proportion of our patients (34.5%) were never smokers compared to IPF (19.0-26.7%), which may partly explain the difference in the comorbidity burden [6, 14]. Krauss et al reported 38.6% never smokers in their uILD cohort, which was similar to our ndings in the present study, but lower than in cHP (50.2%) [3,12]. The spectrum of comorbidities included and differences in the approach to registration may also in uence the total number of comorbidities.…”

“…It still remains to be seen whether smoking and environmental and genetic risk factors or the underlying ILD disease is the most signi cant contributor to emphysema. Diabetes is a frequent comorbidity in IPF and other ILDs and was observed in almost 20% of our cohort [3,12,14,20]. The relationship between diabetes and brotic and/or in ammatory ILD has previously been described, but it is unclear whether diabetes is a potential risk factor for disease development or disease progression [21].…”

“…Arterial hypertension is consistently reported as the most common comorbidity in brotic ILD [1-3, 12, 14, 17]. Gastro-esophageal re ux disease (GERD) was among the ve most common comorbidities, similar to what was observed in IPF and uILD [1,2,12,14,17]. The in uence of GERD on disease progression in IPF has been repeatedly discussed and data on anti-acid treatment and surgical fundoplication are con icting [18,19].…”

“…The burden of comorbidities and their association with survival has been characterized in patients with IPF, but there is only limited information about the frequency and type of comorbidities and the impact on survival in patients with uILD [1,2,4,12]. No previous studies have explored combinations of comorbidities and whether they may represent speci c phenotypes in uILD.…”