Radiographic Axial SpondyloarthritisNCT07515131
Respiratory Function and S-index in Radiographic Axial Spondyloarthritis
An observational study of Radiographic Axial Spondyloarthritis, run by Gazi University at 1 site in Turkey (Türkiye).
Trial summary
Radiographic axial spondyloarthritis (r-axSpA) is a chronic inflammatory disease that may lead to reduced chest expansion and impaired respiratory function due to thoracic involvement. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Radiographic Axial Spondyloarthritis
- How many people
- 52 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 3 Jan 2025to 28 Oct 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: The study population consisted of patients diagnosed with radiographic axial spondyloarthritis who were followed at the Department of Physical Medicine and Rehabilitation at Gazi University, and healthy volunteers recruited from the same institution.
Who may be able to join
- Willingness to participate in the study and provide informed consent
- Age ≥18 years
- Absence of any known chronic disease (for the healthy control group)
- Diagnosis of radiographic axial spondyloarthritis according to the Assessment of SpondyloArthritis international Society (ASAS) criteria and absence of any additional chronic disease (for the r-axSpA group)
Who cannot join
- Presence of known cardiopulmonary disease
- Presence of any rheumatologic disease other than radiographic axial spondyloarthritis (r-axSpA)
- Inability to cooperate with testing procedures
- Presence of chest wall or spinal deformities that may restrict lung capacity (e.g., pectus carinatum, pectus excavatum, scoliosis)
- Professional athletes
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Gazi University Hospital, Department of Physical Medicine and Rehabilitation
Ankara, 06560
About this study
Official title: Chest Expansion, Pulmonary Function, and Dynamic Inspiratory Muscle Strength (S-index) in Patients With Radiographic Axial Spondyloarthritis
Radiographic axial spondyloarthritis (r-axSpA) is a chronic inflammatory disease that may lead to reduced chest expansion and impaired respiratory function due to thoracic involvement. While inspiratory muscle strength is commonly assessed using maximum inspiratory pressure (MIP), the S-index is a novel parameter reflecting dynamic inspiratory muscle strength and has not yet been investigated in this population.
This study aims to compare chest expansion, spirometric parameters, and S-index values between individuals with r-axSpA and healthy controls. Additionally, the relationships between these parameters and clinical indices (BASDAI, BASFI, and BASMI) will be evaluated in patients with r-axSpA. The study also aims to explore the potential role of the S-index in the assessment of pulmonary function in this patient group.
Read the detailed description
Radiographic axial spondyloarthritis (r-axSpA) is a systemic, chronic inflammatory rheumatic disease strongly associated with HLA-B27, primarily affecting the sacroiliac joints and the axial skeleton. Its prevalence in the general population ranges between approximately 0.1% and 1.4%. In patients with r-axSpA, involvement of the costovertebral and costosternal joints, as well as the entheses in the thoracic region, may lead to progressive ankylosis over time. This process results in reduced thoracic mobility, decreased chest expansion in the early stages, and a predominantly restrictive pattern of respiratory dysfunction.
Previous studies have investigated the relationships between chest expansion, aerobic capacity, and spirometric parameters with disease activity, functional status, and spinal mobility, as assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), and Bath Ankylosing Spondylitis Metrology Index (BASMI), in individuals with r-axSpA.
Maximum inspiratory pressure (MIP) is widely used for the static assessment of inspiratory muscle strength and has been evaluated in conjunction with chest expansion and spirometric parameters in several studies. In contrast, the S-index is a relatively novel parameter that reflects inspiratory muscle strength dynamically and has not yet been investigated in patients with r-axSpA. Although previous studies have demonstrated moderate to strong correlations between S-index and MIP, these measures represent different physiological aspects of respiratory muscle function and therefore do not yield identical results.
The present study aims to compare chest expansion, spirometric parameters, and S-index values between individuals with r-axSpA and healthy controls. In addition, within the r-axSpA group, the relationships between these parameters and clinical indices (BASDAI, BASFI, and BASMI) will be examined.
Furthermore, the discriminative ability of chest expansion, spirometric parameters, and the S-index in distinguishing individuals with r-axSpA from healthy controls will be evaluated. As a distinctive aspect of this study, S-index values will be analyzed both in comparison between groups and in relation to spirometric parameters, chest expansion, and clinical indices in patients with r-axSpA.
This study is expected to provide novel evidence regarding the potential role of the S-index in the assessment of pulmonary function in patients with r-axSpA.
- Conditions
- Radiographic Axial Spondyloarthritis
- Keywords
- Axial Spondyloarthritis, Radiographic Axial Spondyloarthritis, Ankylosing Spondylitis, S-index, Inspiratory Muscle Strength, Thoracic Expansion, Spirometry, Respiratory Function
- Medical subject headings
- Axial Spondyloarthritis, Spondylitis, Ankylosing, Respiratory Aspiration
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Radiographic Axial Spondyloarthritis (r-axSpA) Group | Individuals diagnosed with radiographic axial spondyloarthritis according to the Assessment of SpondyloArthritis international Society (ASAS) criteria, who were followed at the Department of Physical Medicine and Rehabilitation at Gazi University. Participants underwent standardized assessment of chest expansion, spirometric parameters, inspiratory muscle strength using the S-index, and clinical indices including BASDAI, BASFI, and BASMI | |
| Healthy Control Group | Healthy individuals without a diagnosis of axial spondyloarthritis. Participants will undergo assessment of chest expansion, spirometric parameters, and inspiratory muscle strength using the S-index. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Inspiratory muscle strength assessed by S-index
S-index was measured using the PowerBreathe K5 device (PowerBreathe International Ltd., UK). The test assesses inspiratory muscle strength based on flow and pressure during dynamic inspiration from residual volume to total lung capacity. Measurements were performed under standardized conditions (same device, operator, afternoon hours, 20-25°C). Participants were seated upright with a nasal clip and instructed to perform maximal and rapid inspiratory efforts against resistance after normal expiration. Eight maneuvers were performed in 2-3 sets with ≥30-second rest intervals. The test was considered valid if the difference between the highest three values was <10%, and the highest value was used for analysis.
Measured: Baseline
Secondary outcomes (5)
Pulmonary function parameters (FVC, FEV1, FEV1/FVC, PEF)
Spirometry was performed using a Cosmed device (Omnia, Italy) following calibration before each test. Participants were seated upright with a nasal clip and instructed to perform maximal inspiration followed by forced expiration. Measurements were conducted under standardized conditions (same operator, afternoon hours, 20-25°C). At least three acceptable maneuvers were obtained, and the highest value was recorded if variability was <10%. Up to eight maneuvers were performed with ≥30-second rest intervals. Measurements were evaluated according to ATS/ERS criteria. Parameters recorded included FEV1, FVC, FEV1/FVC, and peak expiratory flow (PEF).
Measured: Baseline
Chest expansion
Chest expansion was measured using a tape measure at the level of the 4th intercostal space with the participant in an upright position. The difference in chest circumference between maximal inspiration and maximal expiration was recorded as chest expansion. Measurements were performed twice, and the highest value was used for analysis.
Measured: Baseline
Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)
Disease activity was assessed using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), a validated 0-10 visual analog scale (VAS)-based instrument consisting of six items evaluating fatigue, spinal pain, peripheral joint symptoms, enthesitis, and morning stiffness. Higher scores indicate greater disease activity.
Measured: Baseline
Bath Ankylosing Spondylitis Functional Index (BASFI)
Functional status was assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI), a validated 0-10 visual analog scale (VAS)-based instrument consisting of ten items evaluating functional limitations in daily activities. Higher scores indicate greater functional impairment.
Measured: Baseline
Bath Ankylosing Spondylitis Metrology Index (BASMI)
Spinal mobility was assessed using the Bath Ankylosing Spondylitis Metrology Index (BASMI), which evaluates five clinical parameters including lateral lumbar flexion, tragus-to-wall distance, modified Schober test, intermalleolar distance, and cervical rotation. Scores range from 0 to 10, with higher scores indicating greater mobility limitation.
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Apr 2026
- Study start3 Jan 2025
- Primary completion28 Oct 2025
- Study completion28 Oct 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Radiographic Axial SpondyloarthritisStudies of the same condition, open and under way.
- More trials run by Gazi UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Enrolment
- 52 participants (actual)
Sponsor and investigators
- Lead sponsor
- Gazi University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Ayse BOZDAS, Gazi University
- Investigators
- Feride N Gogus, MD, Study director, Gazi University Faculty of Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07515131
- Sponsor's protocol ID
- Gazi R-axSpA S-index
- Status last verified
- Mar 2026
- First submitted
- 25 Mar 2026
- Last updated
- 7 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Chest Expansion, Pulmonary Function, and Dynamic Inspiratory Muscle Strength (S-index) in Patients With Radiographic Axial Spondyloarthritis
- ClinicalTrials.gov ID
- NCT07515131
- Acronym / sponsor ID
- Gazi R-axSpA S-index
- Conditions
- Radiographic Axial Spondyloarthritis
- Keywords
- Axial Spondyloarthritis, Radiographic Axial Spondyloarthritis, Ankylosing Spondylitis, S-index, Inspiratory Muscle Strength, Thoracic Expansion, Spirometry, Respiratory Function
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 52 participants (actual)
- Lead sponsor
- Gazi UniversityUniversity, hospital or other
- Study start
- 3 Jan 2025 (actual)
- Primary completion
- 28 Oct 2025 (actual)
- Study completion
- 28 Oct 2025 (actual)
- First posted
- 7 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Radiographic axial spondyloarthritis (r-axSpA) is a chronic inflammatory disease that may lead to reduced chest expansion and impaired respiratory function due to thoracic involvement. While inspiratory muscle strength is commonly assessed using maximum inspiratory pressure (MIP), the S-index is a novel parameter reflecting dynamic inspiratory muscle strength and has not yet been investigated in this population.
This study aims to compare chest expansion, spirometric parameters, and S-index values between individuals with r-axSpA and healthy controls. Additionally, the relationships between these parameters and clinical indices (BASDAI, BASFI, and BASMI) will be evaluated in patients with r-axSpA. The study also aims to explore the potential role of the S-index in the assessment of pulmonary function in this patient group.
Detailed description
Radiographic axial spondyloarthritis (r-axSpA) is a systemic, chronic inflammatory rheumatic disease strongly associated with HLA-B27, primarily affecting the sacroiliac joints and the axial skeleton. Its prevalence in the general population ranges between approximately 0.1% and 1.4%. In patients with r-axSpA, involvement of the costovertebral and costosternal joints, as well as the entheses in the thoracic region, may lead to progressive ankylosis over time. This process results in reduced thoracic mobility, decreased chest expansion in the early stages, and a predominantly restrictive pattern of respiratory dysfunction.
Previous studies have investigated the relationships between chest expansion, aerobic capacity, and spirometric parameters with disease activity, functional status, and spinal mobility, as assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), and Bath Ankylosing Spondylitis Metrology Index (BASMI), in individuals with r-axSpA.
Maximum inspiratory pressure (MIP) is widely used for the static assessment of inspiratory muscle strength and has been evaluated in conjunction with chest expansion and spirometric parameters in several studies. In contrast, the S-index is a relatively novel parameter that reflects inspiratory muscle strength dynamically and has not yet been investigated in patients with r-axSpA. Although previous studies have demonstrated moderate to strong correlations between S-index and MIP, these measures represent different physiological aspects of respiratory muscle function and therefore do not yield identical results.
The present study aims to compare chest expansion, spirometric parameters, and S-index values between individuals with r-axSpA and healthy controls. In addition, within the r-axSpA group, the relationships between these parameters and clinical indices (BASDAI, BASFI, and BASMI) will be examined.
Furthermore, the discriminative ability of chest expansion, spirometric parameters, and the S-index in distinguishing individuals with r-axSpA from healthy controls will be evaluated. As a distinctive aspect of this study, S-index values will be analyzed both in comparison between groups and in relation to spirometric parameters, chest expansion, and clinical indices in patients with r-axSpA.
This study is expected to provide novel evidence regarding the potential role of the S-index in the assessment of pulmonary function in patients with r-axSpA.
Study design
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Radiographic Axial Spondyloarthritis (r-axSpA) Group | – | –Individuals diagnosed with radiographic axial spondyloarthritis according to the Assessment of SpondyloArthritis international Society (ASAS) criteria, who were followed at the Department of Physical Medicine and Rehabilitation at Gazi University. Participants underwent standardized assessment of chest expansion, spirometric parameters, inspiratory muscle strength using the S-index, and clinical indices including BASDAI, BASFI, and BASMI |
| Healthy Control Group | – | –Healthy individuals without a diagnosis of axial spondyloarthritis. Participants will undergo assessment of chest expansion, spirometric parameters, and inspiratory muscle strength using the S-index. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- The study population consisted of patients diagnosed with radiographic axial spondyloarthritis who were followed at the Department of Physical Medicine and Rehabilitation at Gazi University, and healthy volunteers recruited from the same institution.
Key inclusion criteria (4 listed)
- Willingness to participate in the study and provide informed consent
- Age ≥18 years
- Absence of any known chronic disease (for the healthy control group)
- Diagnosis of radiographic axial spondyloarthritis according to the Assessment of SpondyloArthritis international Society (ASAS) criteria and absence of any additional chronic disease (for the r-axSpA group)
Key exclusion criteria (5 listed)
- Presence of known cardiopulmonary disease
- Presence of any rheumatologic disease other than radiographic axial spondyloarthritis (r-axSpA)
- Inability to cooperate with testing procedures
- Presence of chest wall or spinal deformities that may restrict lung capacity (e.g., pectus carinatum, pectus excavatum, scoliosis)
- Professional athletes
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Inspiratory muscle strength assessed by S-index
Time frame: Baseline
S-index was measured using the PowerBreathe K5 device (PowerBreathe International Ltd., UK). The test assesses inspiratory muscle strength based on flow and pressure during dynamic inspiration from residual volume to total lung capacity. Measurements were performed under standardized conditions (same device, operator, afternoon hours, 20-25°C). Participants were seated upright with a nasal clip and instructed to perform maximal and rapid inspiratory efforts against resistance after normal expiration. Eight maneuvers were performed in 2-3 sets with ≥30-second rest intervals. The test was considered valid if the difference between the highest three values was <10%, and the highest value was used for analysis.
5 secondary outcomes
Pulmonary function parameters (FVC, FEV1, FEV1/FVC, PEF)
Time frame: Baseline
Chest expansion
Time frame: Baseline
Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)
Time frame: Baseline
Bath Ankylosing Spondylitis Functional Index (BASFI)
Time frame: Baseline
Bath Ankylosing Spondylitis Metrology Index (BASMI)
Time frame: Baseline
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Apr 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Feride N Gogus, MD study director
Gazi University Faculty of Medicine
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Radiographic Axial Spondyloarthritis, run by Gazi University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Inspiratory muscle strength assessed by S-index (time frame: Baseline). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Apr 2026.