Asthma: diagnosis, monitoring and chronic asthma management (BTS, NICE, SIGN) Summary

The British Thoracic Society (BTS), National Institute for Health and Care Excellence (NICE), and the Scottish Intercollegiate Guidelines Network (SIGN) have collaboratively developed comprehensive guidelines to enhance the diagnosis, monitoring, and management of asthma across all age groups. This document focuses on the diagnostic processes for adults, young people over 16, and children aged 5 to 16, emphasizing the pivotal role of Fractional Exhaled Nitric Oxide (FeNO) testing.

1. Initial Clinical Assessment

A thorough clinical assessment is the cornerstone of asthma diagnosis. Healthcare professionals should meticulously document the patient's medical history, focusing on symptoms such as wheezing, shortness of breath, chest tightness, and cough, particularly if these symptoms are variable and associated with triggers like allergens or exercise. A detailed family history of asthma or other atopic conditions should also be considered. Physical examination may reveal wheezing or other signs indicative of airflow obstruction.

2. Objective Tests for Diagnosing Asthma

Objective testing is essential to confirm an asthma diagnosis, as it provides measurable evidence of airway inflammation and variability in lung function.

2.1. Adults and Young People Over 16

The diagnostic algorithm for adults and young people over 16 involves a sequential approach:

• FeNO Testing: Measure the FeNO level to assess eosinophilic airway inflammation. A FeNO level of 50 parts per billion (ppb) or more supports an asthma diagnosis.
• Blood Eosinophil Count: If FeNO testing is unavailable, assess blood eosinophil levels. An elevated eosinophil count above the laboratory reference range supports an asthma diagnosis.
• Bronchodilator Reversibility (BDR) with Spirometry: Conduct spirometry to measure lung function and assess reversibility after administering a bronchodilator. An increase in Forced Expiratory Volume in one second (FEV₁) of 12% or more from baseline, along with an absolute increase of at least 200 ml, indicates reversible airflow obstruction characteristic of asthma.
• Peak Expiratory Flow (PEF) Variability: If BDR testing is delayed or not available, monitor PEF variability. An amplitude percentage mean of 20% or more is indicative of asthma.
• Bronchial Challenge Test: If previous tests are inconclusive, perform a bronchial challenge test to assess airway hyperresponsiveness. A positive test confirms asthma.

2.2. Children Aged 5 to 16

The diagnostic approach for children aged 5 to 16 is tailored to their developmental capabilities:

• FeNO Testing: Measure the FeNO level to detect eosinophilic airway inflammation. A FeNO level of 35 ppb or more supports an asthma diagnosis.
• Bronchodilator Reversibility (BDR) with Spirometry: Conduct spirometry to evaluate lung function and assess reversibility after bronchodilator administration. An increase in FEV₁ of 12% or more from baseline indicates reversible airflow obstruction.
• Peak Expiratory Flow (PEF) Variability: If BDR testing is delayed or not available, monitor PEF variability. An amplitude percentage mean of 20% or more is suggestive of asthma.
• Allergy Testing: Assess for atopic conditions through skin prick tests or measurement of total Immunoglobulin E (IgE) levels. Evidence of sensitization, particularly to common allergens like house dust mites, supports an asthma diagnosis.
• Blood Eosinophil Count: If total IgE is raised, measure blood eosinophil levels. An eosinophil count greater than 0.5 x 10⁹ per litre supports an asthma diagnosis.
• Referral to Specialist: If diagnostic uncertainty persists after these tests, refer the child to a paediatric respiratory specialist for further evaluation, which may include a bronchial challenge test.

3. Role of FeNO Testing

FeNO testing is a non-invasive method that measures the concentration of nitric oxide in exhaled breath, serving as a biomarker for eosinophilic airway inflammation. Its advantages include:

• Early Detection: FeNO levels can rise before clinical symptoms manifest, allowing for earlier intervention.
• Monitoring Inflammation: Regular FeNO measurements can help monitor airway inflammation, guiding adjustments in anti-inflammatory therapy.
• Predicting Steroid Responsiveness: Elevated FeNO levels may predict a positive response to corticosteroid treatment, aiding in personalized therapy plans.

Implementing FeNO testing as the initial objective test in the diagnostic pathway enhances diagnostic accuracy and enables targeted treatment strategies.

4. Financial Implications of FeNO Testing

The integration of FeNO testing into primary care settings has significant financial considerations:

• Cost-Effectiveness: By improving diagnostic accuracy, FeNO testing reduces the likelihood of misdiagnosis and inappropriate treatment, leading to cost savings.
• Resource Allocation: Initial investments in FeNO equipment and training are offset by long-term savings from decreased hospital referrals and admissions due to better-managed asthma.
• Healthcare Efficiency: FeNO testing facilitates prompt and accurate diagnosis within primary care, reducing the burden on secondary care services and optimizing healthcare resource utilization.

The NICE resource impact summary report provides detailed analyses supporting the cost-effectiveness of FeNO testing in asthma diagnosis and management.

Monitoring Asthma Control

Regular monitoring is essential to ensure the effectiveness of asthma management plans. Objective tests combined with patient-reported outcomes provide a comprehensive view of asthma control.

Clinical Monitoring:

1. Symptom Review:
• Conduct regular assessments of symptom frequency, severity, and triggers.
• Monitor nocturnal symptoms and their impact on the patient's daily life.
2. Medication Adherence and Inhaler Technique:
• Check adherence to prescribed medications.
• Ensure patients are using inhalers correctly; incorrect technique can reduce efficacy.
3. Action Plans:
• Develop and review personalised asthma action plans with patients.
• Include steps for recognising worsening symptoms and when to seek medical attention.

Financial Evaluation of FeNO Testing

FeNO testing provides numerous financial and clinical benefits that justify its incorporation into primary care diagnostic pathways.

1. Cost-Effectiveness:
• Reduction in Misdiagnosis: FeNO testing reduces unnecessary use of medications prescribed for asthma-like conditions, preventing financial and health burdens from inappropriate treatments.
• Minimisation of Secondary Care Referrals: By providing a clear diagnosis in primary care, FeNO testing reduces referrals to specialists, saving healthcare costs.
2. Impact on Resource Allocation:
• Investment Recovery: Initial costs for FeNO equipment and staff training are offset by reduced long-term management costs, including fewer exacerbations and emergency hospital visits.
• Economic Evaluation from NICE: A detailed cost analysis by NICE confirms significant savings by avoiding trial-and-error treatment and minimising steroid overprescription. (NICE Resource Impact Report)
3. Public Health and Workforce Impacts:
• Reduced absenteeism due to better-managed asthma supports workforce productivity.
• Enhanced diagnostic accuracy also improves patient satisfaction and trust in the healthcare system.

Specific Pathways for Children and Adults

Adults and Young People Over 16

Objective Tests Pathway:

• Step 1: FeNO Testing:
• FeNO levels ≥50 ppb are strongly indicative of eosinophilic inflammation, supporting asthma diagnosis.
• Step 2: Spirometry with BDR Testing:
• Assess FEV₁ changes pre- and post-bronchodilator.
• Improvement of ≥12% and ≥200 ml in FEV₁ confirms reversibility consistent with asthma.
• Step 3: Peak Expiratory Flow (PEF) Variability:
• Perform PEF monitoring if spirometry is inconclusive.
• Variability >20% is diagnostic for asthma.
• Step 4: Bronchial Challenge Test:
• Consider this if uncertainty remains after FeNO and spirometry.
• Outcome:
• Combine clinical findings with test results to confirm or exclude asthma.

Action on Uncertainty:

• If all tests are inconclusive, consider alternative diagnoses such as chronic obstructive pulmonary disease (COPD) or vocal cord dysfunction.

Children Aged 5 to 16

Objective Tests Pathway:

• Step 1: FeNO Testing:
• A FeNO level ≥35 ppb supports asthma diagnosis in children.
• Step 2: Spirometry with BDR Testing:
• Reversibility testing identifies airway obstruction that improves with bronchodilator use.
• Step 3: Allergy Testing:
• Screen for allergic sensitisation using skin prick tests or IgE levels.
• Step 4: PEF Monitoring:
• Use if spirometry and other tests are unavailable.
• Outcome:
• Diagnose asthma based on a combination of objective test results and clinical history.

Integration into Primary Care Clinics

1. Implementation of FeNO Testing:
• Prioritise FeNO as the first diagnostic tool in asthma pathways.
• Train healthcare providers on proper test administration and interpretation.
2. Pathway Simplification:
• Adapt NICE diagnostic algorithms into user-friendly charts for clinic use.
• Ensure decision trees are clear, concise, and accessible to staff.
3. Ongoing Education:
• Provide educational resources to healthcare teams to ensure guideline adherence.
• Promote patient awareness regarding the importance of FeNO testing and asthma action plans.
4. Monitoring and Feedback:
• Collect data on FeNO test use and outcomes to refine diagnostic processes.
• Regularly review pathway performance and cost-effectiveness.

Key Recommendations for Clinics

1. Utilise FeNO Testing First:
• Emphasise FeNO testing as the initial step in diagnosing suspected asthma.
• Equip clinics with FeNO devices to standardise care.
2. Provide Personalised Management Plans:
• Integrate test results into comprehensive asthma care, including medication adjustments.
3. Evaluate Financial and Clinical Benefits:
• Highlight cost savings from reduced hospital referrals and improved asthma control.
• Advocate for funding to support the widespread adoption of FeNO testing.

This document provides clinics with actionable steps to implement evidence-based asthma diagnostic practices, improving both clinical outcomes and cost-effectiveness. For more information, refer to the NICE guidelines and associated algorithms (NG245).

 

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