Comparing Advanced Technologies to Standard Testing for the Diagnosis of Airway Disease in Hospital and Community Settings

Long-term lung conditions such as COPD affect around one in five people and are the third leading cause of death in England. These conditions are often not picked up until they have reached an advanced stage, and sometimes people are given an incorrect diagnosis. They cause breathing difficulties due to lung damage, which cannot be reversed in the case of COPD.

At present, lung conditions are usually diagnosed through breathing tests like spirometry. These tests require people to blow forcefully into a machine several times, which can be uncomfortable and difficult for some patients. They also rely on specialist equipment and must be carried out and interpreted by highly trained professionals. Because there aren't enough of these professionals, waiting lists can be long. Even when spirometry is possible, it does not always detect lung disease early.

Two national NHS programmes - the Community Diagnostic Centre (CDC) programme and the Lung Cancer Screening (LCS) programme - create opportunities to find lung disease earlier. However, the same challenges with spirometry remain.

Recently, new types of lung tests have been developed. These tests may be simpler, quicker, and cheaper to use, but they are not yet part of standard NHS care. We need to find out whether these new tests can identify lung disease as well as, or better than, spirometry, especially at earlier stages. If they can, they may help prevent further lung damage and improve health outcomes. It is also important to understand how practical and cost-effective these tests are, and whether they could be used widely in different healthcare settings.

To explore this, we will carry out the new tests alongside traditional lung function tests in both community and hospital settings. We will invite adults with possible COPD who:

* have been referred for spirometry at local CDCs,
* have been referred for lung function testing at secondary care hospitals,
* are attending for a lung scan as part of the LCS pathway, and
* are attending local community groups or events.

Participants may also be asked to complete short surveys or optional interviews to share their experiences. Healthcare professionals working in testing centres will be invited to do the same. We are especially keen to hear from people who live with lung conditions or who experience health inequalities, so that we can understand how easy the tests are to use, how comfortable they are, and whether they could work well across different healthcare settings.

• Capnography (Diagnostic test): Capnography used in combination with machine learning-derived algorithms, with or without reversibility testing (if indicated on spirometry)
• Oscillometry (Diagnostic test): Oscillometry (where applicable), with or without reversibility testing (if indicated on spirometry). Measures respiratory impedance during normal tidal breathing.
• FENO (Diagnostic test): Fractional exhaled nitric oxide (if requested). Used to assess airway inflammation.
• Gas Transfer (Diagnostic test): Assesses lung diffusing capacity, performed using full pulmonary function testing equipment
• Static Lung Volumes (Diagnostic test): Body plethysmography (if applicable). Used to assess static lung volumes and, where applicable, specific resistance, performed using full lung function equipment
• Spirometry (Diagnostic test): Spirometry, with or without reversibility testing

Primary outcomes

• Diagnostic accuracy of capnography used in combination with machine learning-derived algorithms [Baseline]: Sensitivity, Specificity, PPV, NPV compared to clinician diagnosis of COPD

Secondary outcomes

• Diagnostic accuracy of oscillometry [Baseline]: Sensitivity, Specificity, PPV, NPV compared to clinician diagnosis of COPD
• Time per test [Baseline]: Time per test of advanced diagnostic technologies compared to usual care
• Comparative 'failure rate' [Baseline]: Comparative 'failure rate' of advanced diagnostic technologies compared to usual care
• Usability and acceptability [Baseline]: Patients' perceptions on the usability and acceptability of advanced respiratory diagnostic technologies compared to existing tests such as spirometry via a non-validated questionnaire
• Usability and acceptability [Baseline]: Healthcare practitioners' perceptions on the usability, acceptability and confidence in advanced respiratory diagnostic technologies via semi-structured interviews
• Effectiveness of advanced technologies in detecting early, alternative, or precursor respiratory conditions [Baseline]: Identification of pre-COPD using advanced respiratory diagnostic technologies in patients with normal forced expiratory volume in 1 second (FEV1) / forced vital capacity (FVC) ratio on spirometry but signs of reduced FEV1, gas trapping, hyperinflation, or reduced diffusing capacity on additional lung function tests performed in secondary care, or emphysema on CT scan. Differentiation of COPD from asthma using advanced diagnostic tests, particularly in patients presenting with overlapping respiratory symptoms
• Feasibility outcomes in Lung Cancer Screening pathway [Baseline]: Recruitment uptake rate, time required and the acceptability to both patients and healthcare professional to complete additional diagnostic testing in individuals invited for low-dose CT (LDCT) as part of the lung cancer screening (LCS) pathway

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* ≥ 18 years of age
* New referral to community or secondary healthcare services
* Clinical suspicion of airway disease/COPD
* Able to provide fully informed written consent
* Able to fully understand and cooperate with the study protocol
* Clinically stable with no contraindications to lung function testing (outlined below)

Exclusion Criteria:

* Confirmed diagnosis of COPD
* Not willing and/or able to provide fully informed written consent to participate
* Has a relative contraindication to lung function testing \[18\]:
* Recent thoracic, abdominal or eye (e.g. cataract) surgery < 6 weeks
* Unstable cardiovascular status, including recent myocardial infarction or pulmonary embolus < 6 weeks
* Pneumothorax < 6 weeks
* Haemoptysis of unknown origin < 6 weeks
* Thoracic, abdominal or cerebral aneurysm
* Chest infection < 6 weeks
* An acute illness or symptom that might interfere with test performance (e.g. nausea, vomiting).
* The presence of any other clinical condition that would prevent the individual from safely performing lung function tests