First-Line Diagnostic Investigations for Suspected Adult Asthma

Comparative Diagnostic Accuracy of First-line Objective Tests for Asthma in Adults With Suspected Disease: Evaluation of Individual and Combined Tests, and the Impact of Normal Spirometry and Obesity.

Asthma is a common long-term condition that can be difficult to diagnose accurately. Symptoms such as breathlessness, wheeze and cough can vary over time and may be caused by other conditions. Some people with asthma have normal breathing test results when they are assessed, which can make diagnosis challenging and lead to delays in treatment.

This study aims to determine which commonly used tests, either alone or in combination, are most accurate for diagnosing asthma in adults with suspected disease. Participants referred to George Eliot Hospital for investigation of possible asthma will be invited to take part.

Following informed consent, participants will undergo a range of routine diagnostic tests during their first visit. These include spirometry with bronchodilator response testing in patient with both normal airway function and airflow obstruction, fractional exhaled nitric oxide (FeNO), which measures airway inflammation, and oscillometry, which assesses how air moves through the lungs. Participants will then attend a second visit for a bronchial provocation challange test, which helps determine whether the airways are unusually sensitive, a key feature of asthma.

The study will compare the results of these tests with the final diagnosis to assess how accurately each test identifies or excludes asthma. It will also investigate whether combining different tests improves diagnostic accuracy and whether factors such as obesity affect diagnostic measurements of increased asthma prevalence.

The findings will help improve understanding of the most effective ways to diagnose asthma in routine clinical practice. This may lead to faster and more accurate diagnoses, reduce the need for unnecessary investigations, and support better care for people with suspected asthma.

Inclusion Criteria:

• •Adults aged 16years and older

  • Referral for objective investigation of suspected asthma
  • Ability to provide written informed consent

Exclusion Criteria:

• Previous confirmed diagnosis of asthma or other chronic airways disease
• Respiratory tract infection within six weeks prior to testing
• Current smoker or ex-smoker with a greater than 10p\pack-year smoking history
• Inability to perform pulmonary function testing to acceptable technical standards
• Contraindications to any of the diagnostic investigations as per departmental guidelines
• Lack of capacity to provide informed consent