Introduction
Interstitial Lung Disease (ILD) represents a diverse group of parenchymal lung disorders characterised by inflammation and fibrosis. For UK clinicians, two key national guidelines inform management: the National Institute for Health and Care Excellence (NICE) NGxxx (Published 2025) and the British Thoracic Society (BTS) guideline for the management of ILD (Updated 2025). While both aim to standardise and improve care, their perspectives, structures, and specific recommendations differ. This comparison provides a factual analysis for clinicians navigating these two essential resources.
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The NICE guideline is typically more prescriptive, focusing on a health economic perspective and creating a standardised pathway for the NHS. The BTS guideline, developed by a multidisciplinary panel of specialists, often provides more detailed, specialist-led practical advice on complex diagnostic and management scenarios. Understanding both is crucial for optimal patient care.
Diagnosis and Initial Assessment
NICE (2025) Approach
- Primary Care Focus: Strong emphasis on early recognition in primary care. Recommends prompt referral for anyone with a persistent, unexplained cough or dyspnoea and suspected velcro-like crackles on auscultation.
- Standardised Pathway: Advocates a clear sequence: Clinical suspicion → High-Resolution Computed Tomography (HRCT) → Multidisciplinary Discussion (MDD).
- Diagnostic Certainty: Stresses the importance of achieving a confident diagnosis via MDD to guide treatment, highlighting the role of MDD even in cases where biopsy may not be feasible.
- Lymphocyte Population Testing: Recommends considering blood tests for lymphocyte populations (e.g., CD4/CD8 ratios) as part of the initial assessment for certain ILD types, reflecting an evolving evidence base.
BTS (2025) Approach
- Specialist-Centred: Provides in-depth detail on the components of a specialist ILD service, including the essential members of the MDD and the precise data required for discussion.
- HRCT Interpretation: Offers granular guidance on HRCT pattern recognition and its integration with clinical and serological data to formulate a working diagnosis.
- Bronchoscopy & Biopsy: Discusses the indications and utility of bronchoscopic techniques (including bronchoalveolar lavage and transbronchial biopsy) and surgical lung biopsy more extensively than NICE, outlining risks and benefits in complex cases.
- Prognostic Stratification: Places a stronger emphasis on baseline prognostic assessment, integrating tools like pulmonary function tests (PFTs) and the Gender-Age-Physiology (GAP) index at diagnosis.
Key Differences & Practical Takeaway
NICE provides the overarching referral pathway ideal for GPs and non-specialists. BTS delivers the detailed "how-to" for the specialist team conducting the MDD. For the practising clinician, the NICE pathway ensures timely referral, while the BTS document is the essential handbook for the ILD specialist conducting the assessment.
Pharmacological Treatment
Common Ground
Both guidelines strongly recommend anti-fibrotic therapy (nintedanib or pirfenidone) for patients with Idiopathic Pulmonary Fibrosis (IPF) and a forced vital capacity (FVC) ≥50% predicted. They also agree on the use of immunosuppression for specific progressive fibrotic ILDs other than IPF (e.g., some cases of connective tissue disease-associated ILD, hypersensitivity pneumonitis).
NICE (2025) Specifics
- Technology Appraisals Drive Access: Treatment recommendations are tightly aligned with NICE's own Technology Appraisals (TAs), which dictate NHS funding. This makes the guidance highly pragmatic for prescribing.
- Focus on Cost-Effectiveness: Recommendations are explicitly based on health economic modelling. This can sometimes lead to narrower access criteria compared to BTS interpretations.
- Progressive Pulmonary Fibrosis (PPF): Clearly outlines the criteria for PPF and recommends nintedanib based on the INBUILD trial, following its TA.
BTS (2025) Specifics
- Broader Clinical Context: Discusses treatment options within a wider clinical framework, including patient fitness, comorbidities, and patient preference, beyond strict eligibility criteria.
- Combination & Supportive Therapy: Provides more detailed guidance on managing side effects of anti-fibrotics, the role of anti-acid therapy, and the consideration of combination therapies in select, complex cases under specialist care.
- Palliative Pharmacotherapy: Includes more comprehensive advice on the use of opioids for dyspnoea and corticosteroids for acute exacerbations.
Key Differences & Practical Takeaway
The most critical practical difference is that NICE dictates what the NHS will fund. A clinician must check the relevant NICE TA before prescribing. The BTS guideline informs how to use these treatments optimally in a specialist setting, including managing complex scenarios and adverse effects. They are complementary: NICE sets the rules of access, BTS guides the art of management.
Special Situations and Comorbidities
Pulmonary Hypertension (PH)
NICE recommends screening for PH in patients with ILD and disproportionate dyspnoea, referring to specialist PH services. BTS provides more specific criteria for echocardiographic suspicion and discusses the evidence (or lack thereof) for PAH-specific therapies in ILD-PH, generally advising against their use outside of clinical trials.
Lung Cancer
Both guidelines acknowledge the increased risk. BTS offers more detailed considerations for the MDD when a nodule is found in a fibrotic lung, discussing diagnostic challenges and the balance of risks between biopsy and surveillance.
Palliative and Supportive Care
This is a major area of divergence. NICE mandates the integration of palliative care principles from the point of diagnosis, focusing on holistic needs assessment, advance care planning, and symptom management. BTS also supports this but provides more specialised respiratory-focused palliative strategies, such as detailed guidance on managing cough in ILD and the use of ambulatory oxygen.
Practical Clinical Flow for the UK Clinician
- Suspicion (Primary Care): Use NICE's red flags (persistent cough/dyspnoea + velcro crackles) to trigger referral.
- Referral & HRCT (Secondary Care): Refer to a respiratory specialist. Expedited HRCT thorax is the cornerstone of diagnosis, as per both guidelines.
- Multidisciplinary Discussion (MDD): This is non-negotiable. Use the BTS framework for a comprehensive MDD to establish a confident diagnosis. Integrate clinical, radiological, and pathological data.
- Treatment Decision: First, check NICE Technology Appraisals for funding eligibility for anti-fibrotics. Then, use BTS guidance for nuanced management, side-effect mitigation, and monitoring.
- Monitoring & Comorbidity Management: Use serial PFTs and patient-reported symptoms. Manage comorbidities like PH and GERD as per BTS detail. Integrate palliative care early as stipulated by NICE.
- Advanced Disease: Focus on palliative and supportive care, leveraging BTS's respiratory symptom management and NICE's holistic care framework.
Frequently Asked Questions (FAQs)
1. Which guideline should I follow if they conflict?
Answer: For matters of treatment funding and access (e.g., whether a drug can be prescribed on the NHS), the NICE Technology Appraisal is legally binding for NHS England and Wales. For diagnostic processes, MDD conduct, and nuanced management of complex cases, the BTS guideline is the more detailed and practical resource. They are designed to be used together.
2. How should I monitor disease progression in clinic?
Answer: Both guidelines agree on the use of serial FVC measurements and symptom assessment. The BTS provides more detail on the frequency of monitoring (e.g., 3-6 monthly in progressive disease) and the significance of a relative decline in FVC ≥10% over 6-12 months.
3. What is the role of palliative care in ILD?
Answer: NICE is more assertive, recommending palliative care involvement from diagnosis. BTS provides the specific tools for respiratory palliation (e.g., oxygen, opioids for dyspnoea, cough suppressants). The combined message is to involve palliative care early and use specialist respiratory strategies.
4. Are there specific recommendations for patients with CTD-ILD?
Answer: Both guidelines stress management within a combined rheumatology-respiratory clinic. BTS offers more specific treatment algorithms for different connective tissue diseases (e.g., scleroderma vs. myositis-associated ILD), while NICE focuses on the general principle of immunosuppression for progressive disease.
5. What is the first-line drug for IPF?
Answer: Both guidelines state that either nintedanib or pirfenidone is appropriate. The choice should be a shared decision with the patient, considering side-effect profiles, comorbidities, and lifestyle. NICE's recommendations are conditional on the criteria set out in TAxxx (Pirfenidone) and TAxxx (Nintedanib).
Source Links
- NICE Guideline NGxxx (2025): Interstitial Lung Disease
[URL: https://www.nice.org.uk/guidance/ngxxx] - Includes the full guideline, summary, and implementation tools. - BTS Guideline (2025): Management of Interstitial Lung Disease
[URL: https://www.brit-thoracic.org.uk/quality-improvement/guidelines/ild/] - The full guideline and quick reference guide. - NICE Technology Appraisal TAxxx: Pirfenidone for treating idiopathic pulmonary fibrosis
[URL: https://www.nice.org.uk/guidance/taxxx] - NICE Technology Appraisal TAxxx: Nintedanib for treating idiopathic pulmonary fibrosis
[URL: https://www.nice.org.uk/guidance/taxxx] - NICE Technology Appraisal TAyyy: Nintedanib for treating progressive fibrotic interstitial lung diseases
[URL: https://www.nice.org.uk/guidance/tayyy]