How Much Severe is the Severe Asthma of Patients Who Will be Medicated With Mepolizumab? Μeasurement of Respiratory Mechanics by Means of Impulse Oscillometry in Severe Eosinophilic Asthmatics Before and After Mepolizumab Initiation
Conditions: Severe Asthma
Sponsor: University of Thessaly

Protocol information 
Full title: 
Impulse Oscillometry Measurements in Severe Eosinophilic 
Asthmatics Before and After Anti-IL-5 Factor Initiation (IMPOSE) 
ClinicalTrials.gov ID NCT05147155 
Sponsor University of Thessaly 
Information provided by Ourania Kotsiou, University of 
Thessaly (Responsible Party) 
Last Update Posted 2024-05-10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Title of the trial for lay people, in easily understood, i.e., non-technical, language:  
Impulse oscillometry as a method to document and monitor the efficacy of anti-IL-5 
factor in patients with severe eosinophilic asthma. 
 
SCIENTIFIC RATIONALE 
Asthma is an inflammatory airways disease affecting the entire bronchial tree. 
The importance of small airways in asthma has been well documented [1,2]. Small 
airways defined as those with an internal diameter of 2 mm or less, which referred to 
as the silent zone of the lungs. Small airway disease (SAD) is present across patients 
with all stages of asthma, but it is particularly prevalent in those with more severe 
disease and more frequent symptoms [3]. Particularly, the silent zone has been 
related to asthma control, severity, and risk of exacerbation [3,4]. SAD is more 
prevalent in asthmatic patients with fixed airflow obstruction compared to asthmatic 
patients without fixed airflow obstruction [5].  
The small airways contribute to the resistance in the airways of patients with 
obstructive airways disease [6]. It was estimated that total small airways resistance 
was 24% of total airway resistance in healthy adults and increased to 34% in 
asymptomatic newly diagnosed patients with asthma and 51% in patients with severe 
asthma [4].  
Structural alterations at the peribronchiolar level contribute to the 
pathogenesis of functional abnormalities observed in patients with severe asthma [7]. 
Remodeling can affect small airway wall stiffness, thereby changing their distensibility 
[8]. An increase in type collagen, matrix metalloproteinase and fibronectin and a 
decrease in collagen III localized to the outer part of the lung were found in patients 
who died of asthma [9]. It has been recently documented that those structural 
abnormalities in patients with severe asthma associated with a higher frequency of 
exacerbations, worse asthma severity, quality of life, and asthma control [3]. 
Moreover, it has been reported reproducibly higher alveolar NO concentrations in 
refractory asthma group compared to mild-moderate asthma group, supporting the 
hypothesis that refractory asthma is associated with distal lung inflammation [10].  
Although it is increasingly recognized that the small airways play an important 
role in severe asthma and SAD may complicate severe asthma treatment, it is 
notoriously difficult to measure small airways inflammation and/or dysfunction 
[11,12]. SAD is a complex and silent signature of severe asthma that is likely to be 
directly or indirectly captured by combinations of physiological tests, such as 
spirometry, body plethysmography, impulse oscillometry (IOS), and multiple breath 
nitrogen washout. For clinical practice, it is important to adopt easy-to-use clinical 
measures, such as IOS and spirometry, to delineate various severe asthma SAD 
subtypes. 

Heterogeneous airway narrowing is a significant marker of severe asthma 
related to resistance and reactance [13]. IOS seemed to have better sensitivity to 
detect SAD than effort-dependent forced expiratory flow between 25% and 75% 
(FEF25-75%) [11]. Spirometry, which is the standard method for measurement of 
pulmonary function, is unlikely to reflect the pathophysiology of SAD since it measures 
bulk flow propagating predominantly from the larger central airways; therefore, there 
are limitations in detecting changes in small airways and airway trapping in patients 
with asthma [14]. Furthermore, spirometry performance remains challenging for 
many elderly patients who have comorbidities that affect the test procedure, as well 
as in cases where patient cooperation is lacking, such as children or patients with 
physical and cognitive limitations [14]. Therefore, a more readily available test for SAD 
is crucial for patient assessment. 
The use of commercialized forced oscillation technique (FOT) devices to assess 
impedance in obstructive diseases such as asthma has gained popularity. The earlier 
FOT instruments allowed only one sound frequency to be passed at a time. Some of 
the more recent FOTs now use sound waves of two or three different frequencies at 
one time [15]. IOS is an improvised technique of that FOT that could use multiple 
sound frequencies at one time [16]. Although FOT devices are generally comparable, 
IOS is the most commonly used type of FOT in clinical practice [17]. IOS is a noninvasive 
and convenient technique to measure both airway resistance and reactance during 
tidal breathing by an effort-independent and patient-friendly modality for evaluating 
lung function and peripheral airway dysfunction [18], providing extensive description 
of oscillatory pressure and giving better mathematical analyses of resistance and 
reactance using the fast Fourier transform (FFT) technique compared to FOT. In FOT, 
the sound waves of different frequencies were transmitted sequentially, whereas in 
IOS, an impulse, which can be mathematically decomposed into different frequencies, 
is transmitted. This helps in reducing the time of the test and also provides a high 
signal to noise resolution [18]. Resistance can be conceptualized as a sound wave 
requires to travel through the airways and inflate the lung [19]. The reactance of the 
respiratory system is composed of the inert and elastic properties of the respiratory 
system. The sum of the forces ahead of the sound wave (resistance) and those 
generated behind the sound wave in response to the pressure of the wave 
(reactance) equal the impedance of the entire respiratory system; thus permits 
passive measurement of lung mechanics [19]. Importantly, IOS can differentiate small 
airway obstruction from large airway obstruction and is more sensitive than 
spirometry for peripheral airway disease [13,19].  
The clinical classification of SAD into subtypes by use of IOS is meaningful, 
given its association with GINA severity stages, asthma control, quality of life, and 
exacerbations. IOS can be useful in determining baseline lung function, demonstrating 
a response to bronchodilator or bronchoprovocation, and predicting asthma 
exacerbations and loss of disease control especially, in children and elderly with 

obstructive airway diseases [20]. Moreover, the SAD subtype classification with IOS 
has been used to determine the inhaled corticosteroids particle size is needed for 
proper airway inflammation treatment [21]. 
Eosinophilic inflammation in the small airways of patients with severe asthma 
is considered to be an important marker of disease severity [2,22,23). In clinical trials, 
treatment with mepolizumab reduces exacerbation rates by almost a half along with 
modest improvements in symptom scores and forced expiratory volume in 1 s (FEV1) 
early after the first month of commencing mepolizumab treatment [23,24]. However, 
there is an apparent discrepancy between major patient-reported outcomes and lung 
function that should be explored. 
It has recently been reported that mepolizumab improves small airway 
function in severe eosinophilic asthma as detected by multiple-breath nitrogen 
washout test [23]. The improvement in small airway function was seen rapidly after 
the first mepolizumab injection and was associated with a sustained response in the 
majority of patients [23]. However, gaps in knowledge about the choice of device, gas, 
and standardization across systems are key issues leading the committee to conclude 
that multiple-breath nitrogen washout test is not ready for use as a clinical trial 
endpoint in asthmatics [16]. 
In the past few months, Antonicello et al. provided data showed that FOT could 
be an effective method to document and monitor the efficacy of mepolizumab in 
treating severe eosinophilic asthma. In this study, FOT detected early treatment-
induced changes in peripheral airways function [25]. This study included 18 patients 
with severe eosinophilic asthma, candidates for mepolizumab therapy, and no other 
control groups were enrolled [25]. These preliminary results motivate further 
prospective studies to evaluate respiratory mechanics using other FOT devices such 
as the IOS; thus enriching the knowledge regarding the small airway asthma 
phenotype by unlocking the lung’s quiet zone. 
 
 
 
HYPOTHESIS 
We hypothesize that early improvement in small airway function may be a significant 
contributor to the therapeutic response of anti-IL-5 monoclonal antibody therapy in 
patients with severe uncontrolled eosinophilic asthma. We speculate that SAD could 
be effectively evaluated using IOS. Consequently, this study could lead to novel SAD 
subtypes with possible clinical relevance in the context of treatment with anti-IL-5 
factor. We hypothesize that healthy individuals and patients with severe controlled 
asthma would disclose a lesser extent of SAD than patients with severe uncontrolled 
eosinophilic asthma with or without fixed airway obstruction.  

 
OBJECTIVES 
We sought to describe early changes in respiratory mechanics by means of IOS 
in patients with severe eosinophilic asthma commencing mepolizumab treatment. 
The detected parameters will be compared to a group of matched for age and gender 
healthy controls as well as with a group of patients with severe controlled asthma 
matched for age and gender requiring high dose inhaled corticosteroids (ICS) /long-
acting beta-agonist (LABA) combination therapy to prevent asthma from becoming 
uncontrolled. 
 
METHODS 
Study Population  
Our sample will consist of 40 patients between 18 and 82 years of age with 
uncontrolled severe eosinophilic asthma despite receiving high dose ICS/LABA 
combination therapy. 
 
Principal inclusion criteria: 
– Written informed consent 
– Male or female outpatient aged 18 to 82 years inclusive 
– History of bronchial asthma for at least six months as defined by ATS criteria 
[26]. 
The patients will be required to have one or more of the following objective 
physiological criteria: positive results on methacholine or mannitol challenge 
during the previous year, bronchodilator reversibility to 400 mg of inhaled 
Salbutamol of FEV1 ≥12% and 200ml or peak flow variability of ≥20% over two 
weeks.  
– Diagnosis of severe asthma, defined as asthma that requires treatment with 
high dose inhaled corticosteroids plus a second controller and/or systemic 
corticosteroids to prevent it from becoming uncontrolled or that remains 
uncontrolled despite this therapy [27, 28]. 
All patients will be medicated with at least 880 μg of fluticasone propionate or 
the equivalent by inhalation per day and at least three months of treatment 
with an additional controller. Patients will be allowed to continue their anti-
asthma therapy throughout the study.  
– Patients should have uncontrolled asthma commencing mepolizumab 
treatment, based on investigator assessment, including one or both of the 
following: 

-Poor symptom control (frequent symptoms or reliever use, activity limited by 
asthma, night waking due to asthma), defined as ACQ consistently ⩾1.5 or 
ACT<20. 
-Frequent exacerbations (≥2/year) requiring oral corticosteroids, or severe 
exacerbations (≥1/year) requiring hospitalization or burst of systemic 
corticosteroids (≥3 days) [29]. 
– All patients will have an eosinophil count of at least 150 cells per microliter in 
the peripheral blood at screening or at least 300 cells per microliter at some 
time during the previous year.  
 
Control groups  
Control groups will be a set of 50 healthy individuals matched for age and gender and 
40 patients with severe well-controlled asthma requiring high dose ICS/LABA 
combination therapy from becoming uncontrolled, as previously defined, matched for 
age and gender.  
 
Principal exclusion criteria: 
– Diseases and health status: 
-clinically relevant abnormal laboratory values suggesting an unknown disease 
and requiring further clinical evaluation  
-suffering from COPD (i.e., chronic bronchitis or emphysema) and/or other 
relevant lung diseases causing alternating impairment in lung function  
– Asthmatic patients and healthy controls currently smoking or with a smoking 
pack history greater than 10 will be excluded. 
 
Common exclusion criteria: 
– -pregnancy 
-intention to become pregnant during the course of the study 
-breast feeding 
-participation in another study within the 30 days preceding and during the 
present study  
-known or suspected non-compliance, alcohol or drug abuse 
-inability to follow the procedures of the study, e.g., due to language 
problems, psychological disorders 
Sampling  
Approximately 1000 patients with asthma per year are treated in the external 
Unit of Asthma of Respiratory Medicine Department of the University of Thessaly in 

Greece. Nevertheless, in order to certainly achieve the estimated study sample size, 
to maximize the response rate and to reduce survey error, the Respiratory Medicine 
Department of the University of Thessaly will cooperate with a network of private 
respiratory physicians in Central and Northern Greece that serves a population base 
of about 3,000,000. Asthma education programs will regularly take place to raise 
severe asthma awareness, improve asthma control and management by creating a 
community Interlink between Respiratory Medicine Department and private sector 
from across central and northern Greece. 
Furthermore, Respiratory Medicine Department of the University of Thessaly, 
via more than 12 clinical-community partnership spirometry surveillance programs 
with ten primary Health Care Centers in Central and Northern Greece, has already 
created a network of researchers, experts, and healthcare practitioners which is vitally 
important to early identify patients with uncontrolled asthma.  
Ethics 
Verbal and written informed consent will be obtained from all subjects before 
the study, according to the Helsinki declaration [30]. The protocol has already been 
approved by the Larissa University Hospital Ethics Committee (Approval number: 
48841/25/10/2019) 
Target enrolment/sample size: (Required for clinical studies) 
130 (40 patients with severe uncontrolled eosinophilic asthma commencing 
mepolizumab treatment, 40 patients with severe controlled asthma medicating with 
high dose ICS/LABA combination therapy, and 50 healthy individuals matched for age 
and gender) 
 
Anticipated rate of enrolment: (Required for clinical studies) 
1 to 4 patients per month 
 
Estimated study start date: (FSFV/Study Start/Analysis Start) 
May 2020 
 
Estimated study completion date: (LSLV/Study End/Analysis Complete) 
September 2023 
 
Study Design and Methods 
This will be a 2-year prospective, cohort study. Patients will receive mepolizumab, 
which will be administered as a 100-mg subcutaneous dose every four weeks. Subjects 

will be present for subcutaneous mepolizumab (100 mg) injection initially at visit 0 
(Week 0), then for reassessment at two (Week 2) and four weeks (Week 4) and 
continued monthly treatment with reassessment at three (Week 12) and six months 
(Week 26). The patients will not alter their usual treatment regimen between Week 0 
and Week 12; thus mitigating any other potential confounder.  
 
 
Detailed lung function tests will be performed at visit 0 in the following order: the 
fraction of exhaled nitric oxide (FeNO), IOS performance then spirometry and lung 
volumes measurement. All testing will be conducted before and 30 minutes after 
mepolizumab injection. Asthma control and quality of life questionnaires will be filled. 
All testing will be conducted on Week 0, Week 4, Week 12 and Week 26. 
Measurements 
At each clinic visit, we will evaluate the results of spirometric, IOS and lung volumes 
tests and will administer the 5-item Asthma Control Questionnaire (ACQ-5), Asthma 
Control Test (ACT), and Asthma Quality of Life Questionnaire (AQLQ). 
Asthma control questionnaire (ACQ-5) 
Symptom control will be determined using the symptom-only 5-item asthma control 
questionnaire (ACQ-5). A score > 1.5 indicates poor control and an individual change 
> 0.5 is clinically important [31].  
Asthma Control Test (ACT) 
The ACT will provide us with a snapshot of how well asthma has been controlled over 
the last four weeks, giving a score out of 25. A score of less than 20 means that asthma 
may not have been controlled during the past four weeks [32]. 
Asthma Quality of Life Questionnaire (AQLQ) 
The Asthma Quality of Life Questionnaire (AQLQ) is a 20-item self-administered 
questionnaire that covers four dimensions (breathlessness, mood, social limitation 
and worrying) and gives a total score and subscales scores. Patients have to respond 
to a series of statements describing how asthma (or its treatment) affects them and 
indicate which option closely applies to them over the past four weeks. A score of 10 
corresponds to a maximum impairment of quality of life and a score of 0 corresponds 
to no impairment [33]. 

Lung function tests  
Fraction of exhaled nitric oxide (FeNO).  
The fraction of exhaled nitric oxide (FeNO) (MEDISOFT, MEDICAL GRAPHICS CORP, 
Minnesota, USA) will be performed according to American Thoracic Society/European 
Respiratory Society (ATS/ERS) guidelines [20]. Recommended cutoff values for normal 
FeNO levels < 25 parts per billion (ppb) and elevated FeNO > 50 ppb have been 
published [34,35]. 
Impulse Oscillometry (IOS) 
IOS measurements will be performed in triplicate according to standard 
guidelines, with a Jaeger MasterScreen IOS system (Carefusion, Germany, JLAB 
software version 5.22.1.50) [36-38]. A volume calibration will be performed daily using 
a 3-L volume syringe, and the accuracy of resistance measurements will be confirmed 
daily using a standard 0.2 Kpa.s.L−1 resistance mesh. Each patient will be seated 
upright, wear a nose clip, and press on their cheeks with their hands to prevent an 
upper airway shunt. To avoid air leakage, patients will seal their lips tightly around the 
mouthpiece [39-41]. While the impulse will be produced by the speaker is moving with 
the patient’s breathing, a pressure and flow transducer will be measure inspiratory 
and expiratory flow and pressure changes in the respiratory system. Mean values for 
resistance at 5 Hz (R5: indicates total airway resistance); resistance at 20 Hz (R20: 
approximates central airway resistance); the difference between R5 and R20 (R5-R20: 
considered to be an index for small airways); reactance at 5 Hz (X5: relates to 
compliance); resonant frequency (Fres); and integrated area of low-frequency X (AX) 
values will be derived as previously reported [41-44]. Fres and AX are values that 
detect expiratory flow limitations. R5–R20 and AX are thought to reflect changes in 
the quiet zone of the lungs [45]. IOS data will be carefully reviewed offline and quality-
assured by professor K.I Gourgoulianis, an expert clinician, to reject segments affected 
by airflow leak or swallowing artifacts. Acceptability criteria for IOS measurements will 
include coherence values of ≥0.6 at 5 Hz, between test coefficient of variation of Zrs 
of <15% (with a minimum of three tests) and the absence of the following features 
within the flow tracings gauged by visual inspections (swallowing, glottis closure, leak 
around the mouthpiece, improper seal with the nose clip). The best of three 
acceptable attempts with the lowest respiratory resistances will be chosen for the 
final data analysis. During this study, one technician will obtain all IOS measurements.  
Prof. Gourgoulianis make substantial contributions to the clinical application 
of airway diseases with more than 300 publications in this research area [46-68], 
performing measurements with FOT over several decades, be able to educate a 
number of respiratory physicians in Respiratory Medicine Department of University of 
Thessaly by sharing his vast expert knowledge in pulmonary physiology, FOT, and IOS 
testing and related areas.  

Spirometry 
Spirometry (Spirolab, MIR, Rome, Italy) will be performed according to ATS/ERS 
guidelines [69]. Predicted values will be derived from the Global Lung Initiative [70]. 
To avoid any negative effects of forced expiration on the airway, spirometry will never 
be performed before the IOS measurements. The percent predicted forced vital 
capacity (%FVC), the percent predicted forced expiratory volume in 1 s (%FEV1), the 
FEV1/FVC ratio, the percent predicted the maximal mid-expiratory flow (%MMEF), and 
the percent predicted peak expiratory flow (%PEF) would be obtained. The best of at 
least 
three 
technically 
acceptable 
results 
will 
be 
selected. 
 
Constant volume plethysmograph 
Lung volumes measurement [total lung capacity (TLC), residual volume (RV), ratio of 
RV/TLC], and airway resistance (Raw) will be measured in a constant volume 
plethysmograph (CardinalHealth, Yorba Linda, CA, USA) as previously described 
[71,72]. 
 
Study Endpoints 
 
The study endpoints will be: 
 
1) To describe early and late changes in respiratory mechanics by means of IOS in 
patients with severe eosinophilic asthma commencing mepolizumab treatment. 
 
The secondary study endpoints will be: 
 
1) To identify differences in respiratory mechanics by means of IOS in patients 
with severe uncontrolled eosinophilic asthma prior to anti-IL-5 therapy 
compared to healthy individuals. 
 
2) To identify differences in respiratory mechanics by means of IOS in patients 
with severe eosinophilic asthma commencing anti-IL-5 treatment compared to 
patients with severe controlled asthma medicated high dose ICS/LABA 
combination therapy. 
3) To investigate the association between RV/TLC ratio, FeNO, spirometric values 
and IOS measurements in patients with severe uncontrolled asthma before 
and after mepolizumab treatment. 
4) To investigate the association between the changes in respiratory mechanics 
by means of IOS and asthma control measurement as defined by ACT and ACQ-

5 questionnaires in patients with severe eosinophilic asthma before and after 
mepolizumab treatment. 
5) To investigate the association between the changes in respiratory mechanics 
by means of IOS and the quality of life measurement as defined by AQLQ in 
patients with severe eosinophilic asthma before and after mepolizumab 
treatment. 
 
 
Statistical Plan or Data analysis 
 
Data will be analyzed using the statistical program SPSS 22 (IBM Corporation, Armonk, 
NY, USA). Quantitative variables will be presented as mean with standard deviation 
(SD), and qualitative variables will be presented as frequencies with percentages. Chi-
square test will be used to explore any associations between qualitative variables. To 
identify differences between two independent groups when the dependent variable 
will either ordinal or continuous, unpaired t-tests or Mann–Whitney U tests will be 
used for normally distributed and skewed data, respectively. Differences between 
more than two unrelated groups will be tested by one-way analysis of variance 
(ANOVA). A result will be considered statistically significant when the P-value will be 
<0.05. 
 
Limitations 
 
This will be the first study to investigate small airway dysfunction using IOS in patients 
with severe uncontrolled eosinophilic asthma commencing mepolizumab treatment. 
While oscillometry measurements are portrayed as a marker of small airway 
dysfunction, the normal reference ranges or threshold to define SAD has not been 
established yet. However, IOS has many advantages as is the most commonly used 
type of FOT in clinical practice including the use of simple tidal breathing maneuvers 
against forced maneuvers applied in spirometry and thus require less effort, while it 
demonstrates a change in early disease wherein spirometry is normal [16]. 
 
 
 
What is your planned publication? Abstract, Manuscript, Study report 
 
• Planned Publication date (Abstract): 
January 2022 
 
• Planned Publication date (Manuscript): 

March 2022 
 
• Planned Publication Date (Study report): 
March 2020 
 
 
 
Planned Publication Date 
(Study report) 
 
Planned Publication date 
(Abstract) 
 
Planned Publication date 
(Manuscript) 
March 2020 
January 2022 
March 2022 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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