Old dilemma: asthma with irreversible airway obstruction or COPD

Abstract

Older asthmatic patients may develop fixed airway obstruction and clinical signs of chronic obstructive pulmonary disease (COPD). We investigated the added value of pathological evaluation of bronchial biopsies to help differentiate asthma from COPD, taking into account smoking, age, and inhaled corticosteroid (ICS) use. Asthma and COPD patients (24 of each category) were matched for ICS use, age, FEV(1), and smoking habits. Five pulmonary and five general pathologists examined bronchial biopsies using an interactive website, without knowing patient information. They were asked to diagnose asthma or COPD on biopsy findings in both a pairwise and randomly mixed order of cases during four different phases, with intervals of 4-6 weeks, covering a maximal period of 36 weeks. Clinically concordant diagnoses of asthma or COPD varied between 63 %-73 %, without important differences between pairwise vs randomly mixed examination or between general vs pulmonary pathologists. The highest percentage of concordant diagnoses was in young asthmatic patients without ICS use and in COPD patients with ICS use. In non ICS users with fixed airway obstruction, a COPD diagnosis was favored if abnormal presence of glands, squamous metaplasia, and submucosal infiltrate was present and an asthma diagnosis in case of abnormal presence of goblet cells. In ICS users with fixed airway obstruction, abnormal presence of submucosal infiltrates, basement membrane thickening, eosinophils, and glands was associated with asthma. Histological characteristics in bronchial biopsies are reproducibly recognized by pathologists, yet the differentiation by histopathology between asthma and COPD is difficult without information about ICS use.

Keywords: Asthma; Asthma COPD Overlap Syndrome; COPD; Pathology.

Fig. 1

Example slide on interactive website. Screenshot of the interactive website, showing a slide with a representative bronchial biopsy at ×20 magnification. The small image in the lower part of the picture is the overview window, showing the current position and size of the large window. The website allowed to view the slides at different magnifications and to navigate into different areas of the bronchial biopsy like a normal microscope

Fig. 2

Example slide on interactive website including the list with pathological criteria. Screenshot of the interactive website, showing a slide (phase 3a) with a representative bronchial biopsy at ×10 magnification. The small image in the lower part of the picture is the overview window, showing the current position and size of the large window. At the right side of the slide the pathologists may record the observed abnormal presence of 12 pathological criteria (yes/no), the diagnosis of asthma or COPD, how sure they feel about the diagnosis, and rank the 3 most relevant features