Ventilation Heterogeneity Is a Treatable Trait in Severe Asthma

Abstract

Background: Ventilation heterogeneity (VH) is a feature of asthma and indicates small airway disease. Nuclear imaging methods assess VH, which can facilitate clinical diagnosis and further our understanding of disease aetiology.

Objective: We sought to assess VH in severe eosinophilic asthma (SEA) using ventilation/perfusion single-photon emission computed tomography (V/P SPECT), and to assess its use as an objective test of the effect of biologic treatment for ventilation defects in SEA.

Methods: Adults (≥18 y) with severe asthma were recruited to participate in a cross-sectional observational study. Participants underwent a clinical assessment and V/P SPECT CT using Technegas as the ventilation agent. Measures were repeated for a nested before-after treatment study in people with SEA commencing biologics.

Results: A total of 62 participants with severe asthma were recruited. From this, 38 participants with SEA were included in the before-after study. The VH was associated with clinical variables such as lung function impairment and significantly improved after monoclonal antibody treatment in the severe asthma group. The changes in VH correlated with change in post bronchodilator forced expiratory volume in 1 second (FEV₁) %predicted (r = -0.503; P = .001) and post bronchodilator FEV₁/FVC (forced vital capacity) (r = -0.415; P = .01).

Conclusions: The VH is clinically significant, measurable, and treatable, which establishes VH as a treatable trait in severe asthma.

Keywords: Asthma; Eosinophil; Small airway disease; Technegas; Treatable traits; V/P SPECT; Ventilation heterogeneity.