Idiopathic Pulmonary Fibrosis (IPF)

1. Topic Overview

Clinical Summary

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung disease (ILD) of unknown aetiology, occurring predominantly in older adults and characterised by the radiological and/or histopathological pattern of usual interstitial pneumonia (UIP). [1,2] It represents the most common and most lethal of the idiopathic interstitial pneumonias, with a median survival of 3-5 years from diagnosis, comparable to many malignancies. [3]

The disease is characterised by inexorable decline in lung function, progressive dyspnoea, and ultimately respiratory failure. The pathophysiological hallmark is aberrant wound healing following repetitive alveolar epithelial injury, leading to excessive extracellular matrix deposition, fibroblast foci formation, and architectural destruction with honeycombing. [4] Importantly, IPF is now understood as an epithelial-driven rather than inflammatory disease, which explains the failure of immunosuppressive therapies and the success of antifibrotic agents.

Two antifibrotic drugs—pirfenidone and nintedanib—have transformed the treatment landscape, reducing the rate of FVC decline by approximately 50%. [5,6] However, neither agent reverses established fibrosis, underscoring the critical importance of early diagnosis and treatment initiation. Lung transplantation remains the only intervention offering potential cure in suitable candidates. [7]

Key Facts

Clinical Pearls

"Velcro Crackles" — The Early Warning Sign: Fine bibasal inspiratory crackles resembling Velcro being pulled apart are present in > 90% of IPF patients. They often precede radiological changes and should prompt HRCT in any patient > 60 with unexplained dyspnoea. Early recognition enables early antifibrotic therapy.

UIP Pattern Makes the Diagnosis: A definite UIP pattern on HRCT (honeycombing + basal/peripheral + reticular abnormality) in the appropriate clinical context (exclusion of other causes) allows confident IPF diagnosis WITHOUT surgical lung biopsy. The 2022 ATS/ERS guidelines emphasise multidisciplinary discussion (MDD) for atypical cases. [2]

Antifibrotics Slow but Don't Cure: Both pirfenidone and nintedanib reduce FVC decline by ~50% annually. [5,6] Neither reverses fibrosis. Early initiation matters—waiting for "significant decline" loses irreplaceable lung function. Treatment is indicated regardless of disease severity.

GAP Index for Prognosis: Gender (male), Age, Physiology (FVC, DLCO) staging system predicts 1-3 year mortality. GAP Stage I: 1-year mortality 5.6%; Stage III: 1-year mortality 39.2%. [8]

Why This Matters Clinically

IPF is a diagnosis that fundamentally changes a patient's life trajectory. The median survival of 3-5 years is comparable to many cancers, yet diagnosis is frequently delayed by 1-2 years due to non-specific symptoms and misattribution to cardiac disease or "normal ageing." Every month of delay represents lost opportunity for antifibrotic therapy.

Key clinical imperatives:

1. Think IPF in any patient > 60 with unexplained exertional dyspnoea and bibasal crackles
2. Refer early to specialist ILD services for HRCT and multidisciplinary diagnosis
3. Start antifibrotics early — do not wait for "significant progression"
4. Discuss transplantation early in suitable candidates (waiting lists are long)
5. Integrate palliative care from diagnosis — parallel care improves quality of life

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2. Epidemiology

Incidence and Prevalence

IPF epidemiology varies significantly by methodology, geography, and case definitions. Contemporary estimates using strict diagnostic criteria suggest: [9,10]

The true incidence is likely underestimated due to diagnostic delays and misdiagnosis. Registry studies suggest incidence may be rising independently of improved recognition, possibly related to environmental factors and ageing populations. [9]

Demographics

Risk Factors

Established Risk Factors

Environmental and Occupational Exposures

Genetic Factors

The genetic architecture of IPF has been substantially elucidated: [13]

MUC5B Promoter Polymorphism (rs35705950)

• Present in 30-40% of IPF patients vs 9% of controls
• Paradoxically associated with better survival
• Affects mucin production and mucociliary clearance
• Most significant genetic risk factor (OR 4-8 for heterozygotes)

Telomere-Related Genes

• TERT, TERC, RTEL1, PARN mutations
• Found in 15-20% of familial IPF, 1-3% sporadic
• Associated with short telomeres, premature senescence
• More aggressive phenotype, worse prognosis

Surfactant Protein Genes

• SFTPC, SFTPA2, ABCA3
• Rare but highly penetrant
• Cause ER stress and epithelial dysfunction

Exam Detail: Genetics for Examination

The genetic understanding of IPF is increasingly examination-relevant:

1. MUC5B rs35705950 G>T polymorphism: Minor allele frequency 9% population vs 38% IPF. The "gain-of-function" variant increases MUC5B expression 37-fold in distal airways. Despite causing disease, it paradoxically confers survival advantage once IPF develops—possibly through enhanced mucociliary clearance.

2. Telomerase pathway: TERT/TERC mutations explain familial clustering. Patients have short telomeres (below 10th percentile), manifesting as:

   • Earlier onset IPF
   • Extrapulmonary features (cryptogenic liver cirrhosis, bone marrow failure)
   • Worse transplant outcomes (due to bone marrow toxicity from immunosuppression)

3. Familial IPF: Defined as IPF in ≥2 first-degree relatives. Accounts for 2-20% of cases. Earlier onset (50s vs 60s), similar prognosis. Should prompt genetic counselling.

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3. Pathophysiology

Conceptual Framework

The paradigm shift in understanding IPF pathogenesis has been transformational:

Old Paradigm (Inflammatory)

• Chronic inflammation → fibrosis
• Rationale for corticosteroids/immunosuppression
• Failed: PANTHER-IPF trial showed harm from triple therapy [14]

Current Paradigm (Epithelial-Fibroblast)

• Repetitive epithelial injury → aberrant repair
• Epithelial-mesenchymal crosstalk drives fibrosis
• Validated: Success of antifibrotic agents

Molecular Pathophysiology

Phase 1: Alveolar Epithelial Injury

Triggers (multifactorial, cumulative):

• Microaspiration (GORD-related)
• Environmental particles (dust, pollution)
• Viral infections (CMV, EBV, HHV-8)
• Oxidative stress
• Mechanical stress

Cellular Events:

1. Type II alveolar epithelial cell (AEC2) injury and death
2. ER stress activation (unfolded protein response)
3. Telomere dysfunction and cellular senescence
4. Release of damage-associated molecular patterns (DAMPs)

Phase 2: Aberrant Repair Response

The fundamental defect in IPF is failure of normal epithelial regeneration:

Normal Repair:

• AEC2 proliferates and differentiates to AEC1
• Basement membrane integrity maintained
• Transient fibroblast activation, then apoptosis
• Restoration of normal architecture

IPF Aberrant Repair:

• AEC2 fails to regenerate epithelium
• Basement membrane disruption
• Persistent fibroblast activation
• Resistance to apoptosis
• Progressive matrix accumulation

Exam Detail: Key Molecular Mediators

Nintedanib Mechanism: Triple tyrosine kinase inhibitor targeting:

• VEGFR 1-3 (vascular endothelial growth factor receptors)
• PDGFR α/β (platelet-derived growth factor receptors)
• FGFR 1-3 (fibroblast growth factor receptors)

Pirfenidone Mechanism: Pleiotropic effects:

• TGF-β signalling inhibition
• Anti-inflammatory (↓TNF-α, IL-1β, IL-6)
• Antioxidant properties
• Anti-fibroblast proliferation

Phase 3: Fibroblast Foci Formation

The histological hallmark of UIP is the fibroblast focus:

Characteristics:

• Discrete foci of myofibroblasts and fibroblasts
• Abundant extracellular matrix (collagen I, III, fibronectin)
• Located at interface of normal and scarred lung
• Represents "active front" of disease progression

Myofibroblast Origins:

• Resident fibroblast proliferation (major source)
• Fibrocyte recruitment from bone marrow
• Epithelial-mesenchymal transition (EMT) — controversial
• Pericyte differentiation

Myofibroblast Properties:

• α-smooth muscle actin expression
• High contractility (contributes to restrictive physiology)
• Excessive ECM production
• Resistance to apoptosis (key to disease persistence)

Phase 4: Architectural Destruction

Progressive fibrosis leads to:

Honeycombing:

• Destruction of alveolar architecture
• Cystic airspaces lined by bronchiolar epithelium
• Thick fibrotic walls
• Irreversible

Traction Bronchiectasis:

• Bronchial dilation due to surrounding fibrotic retraction
• Not true bronchiectasis (no bronchial wall pathology)

Vascular Remodelling:

• Muscularisation of pulmonary arterioles
• Intimal fibrosis
• Leads to pulmonary hypertension (complicates 30-50% of advanced IPF)

Pathological Classification: UIP Pattern

The UIP pattern is defined histopathologically by:

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4. Clinical Presentation

Natural History

IPF has an insidious onset with typically 6-24 months of symptoms before diagnosis:

Symptoms

Cardinal Symptoms

Associated Symptoms

Red Flag Symptoms

[!CAUTION] Urgent Assessment Required:

• Acute worsening over days-weeks → Acute exacerbation (AE-IPF) vs infection vs PE
• Haemoptysis → Lung cancer (5x increased risk in IPF)
• Sudden pleuritic chest pain → Pneumothorax
• New leg swelling → Right heart failure, VTE
• Fever → Infection (must exclude before diagnosing AE-IPF)

Signs

General Inspection

Digital Clubbing

• Frequency: 40-75% (higher in more advanced cohorts)
• Character: Symmetric; affects fingers > toes
• Mechanism: Unknown; possibly hypoxia-mediated, VEGF-related
• Significance:
  • More common in IPF than other ILDs
  • Associated with more advanced disease
  • Not a predictor of treatment response

Respiratory Examination

Clinical Pearl: The Velcro Crackle Test

Velcro crackles are generated by the sudden opening of collapsed small airways during inspiration. They are:

• Present in > 90% of IPF patients
• Often detectable before HRCT abnormalities
• Best heard at the bases posteriorly
• May extend upward as disease progresses

Technique: Ask patient to take a deep breath in through the mouth. Listen at multiple sites from bases upward. Crackles are typically loudest at end-inspiration.

Differential of Bibasal Crackles:

• IPF/UIP (fine, dry, Velcro-like)
• NSIP (similar but may be less prominent)
• Pulmonary oedema (coarser, may be wet; responds to diuretics)
• Bronchiectasis (coarser, may change with coughing)
• Asbestosis (similar to IPF; occupational history)

Cardiovascular Examination (for Complications)

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5. Differential Diagnosis

Framework for ILD Differential

When evaluating a patient with suspected IPF, systematically consider:

1. Connective Tissue Disease-Associated ILD (CTD-ILD)

2. Hypersensitivity Pneumonitis (HP)

3. Other Idiopathic Interstitial Pneumonias

4. Occupational/Environmental ILDs

5. Drug-Induced ILD

Common culprits:

• Amiodarone
• Methotrexate
• Nitrofurantoin
• Bleomycin
• Checkpoint inhibitors (immunotherapy)

"Must Not Miss" Diagnoses

[!WARNING] Diagnoses That Require Active Exclusion:

1. CTD-ILD: Treatable with immunosuppression; prognosis differs
2. Chronic Hypersensitivity Pneumonitis: Antigen avoidance may arrest progression
3. Drug-Induced ILD: Cessation may allow recovery
4. Combined Pulmonary Fibrosis and Emphysema (CPFE): Different management considerations

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6. Investigations

Diagnostic Algorithm

PATIENT WITH SUSPECTED IPF
         ↓
┌─────────────────────────────────────────────────────────────────┐
│ STEP 1: CLINICAL ASSESSMENT                                    │
│ • History: Dyspnoea duration, cough, exposures, drugs, CTD Sx  │
│ • Examination: Velcro crackles, clubbing, CTD signs            │
│ • Risk factors: Age > 60, male, smoking, family history         │
└─────────────────────────────────────────────────────────────────┘
         ↓
┌─────────────────────────────────────────────────────────────────┐
│ STEP 2: BASELINE INVESTIGATIONS                                │
│ • HRCT Chest (essential)                                        │
│ • Pulmonary Function Tests (FVC, TLC, DLCO)                    │
│ • Autoantibody screen (ANA, RF, anti-CCP, myositis panel)      │
│ • Blood tests (FBC, U&E, LFTs, BNP)                            │
│ • 6-Minute Walk Test with oximetry                             │
└─────────────────────────────────────────────────────────────────┘
         ↓
┌─────────────────────────────────────────────────────────────────┐
│ STEP 3: HRCT PATTERN CLASSIFICATION (Fleischner/ATS-ERS 2022)  │
│                                                                 │
│ ■ DEFINITE UIP:                                                 │
│   Honeycombing + basal/peripheral + reticular                  │
│   → IPF if causes excluded; no biopsy needed                   │
│                                                                 │
│ ■ PROBABLE UIP:                                                 │
│   Basal/peripheral + reticular ± traction bronchiectasis       │
│   No honeycombing, no features suggesting alternative          │
│   → IPF likely; consider MDT, may avoid biopsy                 │
│                                                                 │
│ ■ INDETERMINATE:                                                │
│   Variable or diffuse distribution; some UIP features          │
│   → Requires MDT; often needs biopsy                           │
│                                                                 │
│ ■ ALTERNATIVE DIAGNOSIS:                                        │
│   Features suggesting HP, NSIP, sarcoidosis, etc.              │
│   → Pursue alternative diagnosis                               │
└─────────────────────────────────────────────────────────────────┘
         ↓
┌─────────────────────────────────────────────────────────────────┐
│ STEP 4: MULTIDISCIPLINARY DISCUSSION (MDD)                     │
│ • Respiratory physician + Radiologist + Pathologist            │
│ • Essential for all ILD diagnoses                              │
│ • May include rheumatology input                               │
│ • Determines need for biopsy vs clinical diagnosis             │
└─────────────────────────────────────────────────────────────────┘
         ↓
┌─────────────────────────────────────────────────────────────────┐
│ STEP 5: SURGICAL LUNG BIOPSY (If Required)                     │
│ • Indeterminate HRCT pattern                                   │
│ • Atypical clinical features                                   │
│ • Young patient (less than 50)                                          │
│ • Consider risks vs benefits (mortality 1-3%)                  │
│ • Transbronchial cryobiopsy increasingly used                  │
└─────────────────────────────────────────────────────────────────┘

High-Resolution CT (HRCT)

HRCT is the cornerstone of IPF diagnosis. The 2022 ATS/ERS/JRS/ALAT guidelines define HRCT patterns: [2]

UIP Pattern Features

Exam Detail: HRCT Interpretation Pearls for Examination

Definite UIP Pattern Requires ALL of:

1. Honeycombing (with or without traction bronchiectasis)
2. Basal and peripheral predominance
3. Reticular abnormality

Probable UIP Pattern:

• Reticular pattern + basal/peripheral distribution + traction bronchiectasis
• WITHOUT honeycombing
• WITHOUT features suggesting alternative diagnosis

Features INCONSISTENT with UIP (suggest alternative):

• Upper or mid-lung predominance → HP, sarcoidosis
• Peribronchovascular predominance → HP, CTD-ILD
• Extensive ground-glass opacity → NSIP, AIP, HP
• Micronodules → HP, sarcoidosis
• Cysts (non-honeycomb) → LAM, LCH
• Mosaic attenuation/air trapping → HP
• Consolidation → COP, infection

Honeycombing vs Emphysema:

• Honeycombing: Thick walls, clustered, subpleural, lower zones
• Emphysema: No walls, upper zones, not clustered

Ground-Glass in IPF:

• Minimal ground-glass acceptable
• Extensive ground-glass should prompt consideration of:
  • NSIP
  • Acute exacerbation of IPF
  • Infection superimposed
  • HP

Pulmonary Function Tests

IPF produces a characteristic restrictive pattern: [2]

Prognostic Thresholds:

• FVC less than 50% predicted: Poor prognosis
• DLCO less than 35% predicted: Poor prognosis, consider transplant referral
• FVC decline > 10% per year: Rapid progressor

Special Consideration — Combined Pulmonary Fibrosis and Emphysema (CPFE):

• Emphysema + IPF co-existing
• FVC may be "preserved" (emphysema causes hyperinflation)
• DLCO severely reduced (both contribute)
• Higher risk of pulmonary hypertension
• Worse prognosis than IPF alone

Six-Minute Walk Test (6MWT)

Laboratory Investigations

Routine Blood Tests

Autoantibody Screen

Essential to exclude CTD-ILD:

Bronchoalveolar Lavage (BAL)

BAL is not diagnostic for IPF but helps exclude alternatives:

Surgical Lung Biopsy

Indications:

• HRCT pattern "indeterminate for UIP"
• Clinical-radiological discordance
• Young patient (less than 50)
• Suspicion of alternative diagnosis

Approaches:

• VATS (Video-Assisted Thoracoscopic Surgery): Preferred; lower morbidity
• Open thoracotomy: Rarely required
• Transbronchial cryobiopsy: Emerging alternative; lower morbidity, adequate samples in experienced centres

Risks:

• Perioperative mortality: 1.7-3.5%
• Acute exacerbation post-biopsy: 10-20%
• Higher risk if FVC less than 50% or DLCO less than 35%

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7. Staging and Prognostic Assessment

GAP Index and Staging System

The GAP (Gender, Age, Physiology) staging system predicts mortality: [8]

GAP Variables and Scoring

GAP Stages and Mortality

Composite Physiologic Index (CPI)

CPI = 91.0 - (0.65 × DLCO% pred) - (0.53 × FVC% pred) + (0.34 × FEV1% pred)

• Accounts for extent of fibrosis vs emphysema
• Better predictor in CPFE patients
• Higher CPI = worse prognosis

Predictors of Rapid Progression

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8. Management

Management Principles

1. Early diagnosis and early treatment — every month of delay loses lung function
2. Antifibrotic therapy for all — do not wait for "significant" decline
3. Supportive care in parallel — not sequential
4. Transplant assessment early — waiting lists are long
5. Palliative care from diagnosis — parallel, not end-stage only
6. Treat comorbidities — GORD, PH, sleep disorders

Pharmacological Treatment

Antifibrotic Agents

Two antifibrotic drugs are licensed and NICE-approved for IPF: [5,6,15]

Pirfenidone

Clinical Pearl: Pirfenidone Practical Tips

1. GI side effects: Take with or after food; consider anti-emetics; slow titration helps
2. Photosensitivity: Can be severe; avoid midday sun; use high SPF; warn about reflective surfaces (water, snow)
3. Dose adjustment: If intolerable side effects, reduce to 534mg TDS temporarily, then attempt re-escalation
4. Weight loss: Common; monitor weight; consider dietitian input
5. Drug interactions: Avoid fluvoxamine (increases pirfenidone levels); caution with CYP1A2 inhibitors

Nintedanib

Clinical Pearl: Nintedanib Practical Tips

1. Diarrhoea management: Pre-emptive loperamide; hydration; dietary modification; dose reduction to 100mg BD if needed
2. Hepatotoxicity: Check LFTs baseline and regularly; if ALT/AST > 3x ULN, consider dose reduction or interruption
3. Bleeding risk: Hold 3 days before and after surgery/procedures
4. Cardiovascular risk: Caution in patients with recent MI, unstable angina, or stroke
5. Pregnancy: Highly teratogenic; ensure contraception in women of childbearing potential

Choosing Between Pirfenidone and Nintedanib

NICE Guidance: Both are NICE-approved for IPF with FVC 50-80% predicted. [15]

Evidence Base for Antifibrotics

ASCEND Trial (Pirfenidone): [5]

• RCT, n=555 IPF patients
• Primary endpoint: Change in FVC at 52 weeks
• Results: 45% reduction in FVC decline; reduced mortality/disease progression composite

INPULSIS 1 & 2 (Nintedanib): [6]

• Parallel RCTs, n=1066 IPF patients
• Primary endpoint: Annual rate of FVC decline
• Results: 50% reduction in FVC decline (-114 vs -240 mL/year)

Treatments That Do NOT Work

[!WARNING] Evidence of Harm — Avoid These Treatments:

Triple Therapy (Prednisone + Azathioprine + NAC): PANTHER-IPF trial showed increased mortality and hospitalisations. DO NOT USE. [14]

Warfarin: ACE-IPF trial terminated early due to excess mortality. [16]

Sildenafil monotherapy: STEP-IPF showed no significant benefit on 6MWD. [17]

Supportive Care

Oxygen Therapy

Pulmonary Rehabilitation

Strong Evidence (Cochrane review): [18]

• Improves 6MWD, dyspnoea, and quality of life
• Benefits may be modest and short-lived in IPF
• Should be offered to all suitable patients
• Maintenance programmes may sustain benefits

Treatment of Comorbidities

Vaccinations

All IPF patients should receive:

• Annual influenza vaccination
• Pneumococcal vaccination (PCV13, PPSV23)
• COVID-19 vaccination
• Pertussis (Tdap) if not recently received

Lung Transplantation

Lung transplantation is the only intervention that offers potential cure: [7,19]

Indications for Referral

Refer EARLY — ideally at diagnosis if:

• Age-appropriate (less than 65-70, some centres accept up to 75)
• No absolute contraindications
• FVC decline despite antifibrotic therapy
• DLCO less than 35-40% predicted
• 6MWT desaturation less than 88%
• Pulmonary hypertension

ISHLT Criteria for Listing:

• FVC decline ≥10% absolute in 6 months
• DLCO decline ≥15% absolute in 6 months
• Desaturation to less than 88% on 6MWT
• Pulmonary hypertension
• Hospitalisation for respiratory decline

Outcomes

Contraindications

Acute Exacerbation of IPF (AE-IPF)

Definition and Diagnosis

AE-IPF is defined as: [2]

• Acute worsening of dyspnoea (typically less than 1 month)
• New bilateral ground-glass or consolidation on HRCT
• Exclusion of cardiac failure and fluid overload
• Exclusion of identifiable cause (infection, PE, aspiration) — if cause identified, termed "triggered AE"

Clinical Features

Management

ACUTE EXACERBATION MANAGEMENT
             ↓
┌──────────────────────────────────────────────────────┐
│ EXCLUDE ALTERNATIVE CAUSES                           │
│ • Infection (BAL, blood cultures, viral PCR)        │
│ • PE (CTPA if clinical suspicion)                   │
│ • Cardiac failure (Echo, BNP)                       │
│ • Drug toxicity                                     │
└──────────────────────────────────────────────────────┘
             ↓
┌──────────────────────────────────────────────────────┐
│ SUPPORTIVE CARE                                      │
│ • Oxygen (target SpO2 88-92%)                       │
│ • Consider NIV (may bridge to transplant)           │
│ • Early ICU input if deteriorating                  │
│ • Discuss ceiling of care/escalation plan           │
└──────────────────────────────────────────────────────┘
             ↓
┌──────────────────────────────────────────────────────┐
│ CORTICOSTEROIDS (Limited Evidence)                   │
│ • Methylprednisolone 500-1000mg IV daily × 3 days   │
│ • Then oral prednisolone taper                      │
│ • Evidence base weak; widely used                   │
└──────────────────────────────────────────────────────┘
             ↓
┌──────────────────────────────────────────────────────┐
│ CONTINUE/START ANTIFIBROTICS                         │
│ • Continue if already on therapy                    │
│ • Consider initiation if new diagnosis              │
│ • May need to hold briefly if severe GI symptoms    │
└──────────────────────────────────────────────────────┘
             ↓
┌──────────────────────────────────────────────────────┐
│ CONSIDER TRANSPLANT                                  │
│ • Urgent listing if suitable candidate              │
│ • Discuss prognosis honestly                        │
│ • Palliative care involvement                       │
└──────────────────────────────────────────────────────┘

Palliative Care

Palliative care should be integrated from diagnosis, not reserved for end-stage disease:

Symptom Management

Advance Care Planning

Essential components:

• Preferred place of death
• Ceiling of care decisions (NIV, intubation)
• DNACPR discussions
• Lasting power of attorney
• End-of-life wishes

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9. Complications

Disease-Related Complications

Treatment-Related Complications

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10. Prognosis and Outcomes

Natural History

IPF is a progressive, ultimately fatal disease: [3]

Median survival without treatment: 3-5 years from diagnosis Median survival with antifibrotics: Improved but still limited (5-7 years estimated)

Impact of Treatment

Prognostic Factors

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11. Exam-Focused Content

Common Exam Questions

Question 1: "Describe the HRCT features of UIP pattern."

Model Answer: "The UIP pattern on HRCT is characterised by honeycombing, which is the presence of clustered cystic airspaces with thick walls, typically 3-10mm in diameter, predominantly in the subpleural and basal regions. Additional features include reticular abnormality, traction bronchiectasis, and absence of features suggesting alternative diagnoses such as ground-glass predominance, peribronchovascular distribution, or upper-zone predominance."

Question 2: "What is the mechanism of action of nintedanib?"

Model Answer: "Nintedanib is a triple tyrosine kinase inhibitor that targets VEGF receptors 1-3, PDGF receptors α and β, and FGF receptors 1-3. By inhibiting these pathways, it reduces fibroblast proliferation, migration, and differentiation, thereby slowing the fibrotic process. In the INPULSIS trials, it reduced the rate of FVC decline by approximately 50%."

Question 3: "How would you manage a patient with suspected acute exacerbation of IPF?"

Model Answer: "I would first exclude alternative causes including infection with cultures and viral PCR, pulmonary embolism with CT pulmonary angiogram, and cardiac failure with echocardiography. Supportive care with oxygen therapy targeting SpO2 88-92% is essential. Although evidence is limited, I would administer high-dose intravenous methylprednisolone 500-1000mg daily for three days. I would discuss ceiling of care and escalation planning early. If the patient is a transplant candidate, urgent listing should be considered. The prognosis is poor with approximately 50% in-hospital mortality."

Viva Points

Viva Point: Opening Statement: "Idiopathic Pulmonary Fibrosis is a chronic, progressive, fibrosing interstitial lung disease of unknown cause, characterised by the UIP pattern on imaging or histology, occurring predominantly in older adults with a median survival of 3-5 years."

Key Facts to Mention:

• Incidence 3-9/100,000; prevalence 10-60/100,000
• Male:Female ratio 2:1; peak age > 60
• Key symptom: progressive exertional dyspnoea with Velcro crackles
• HRCT: honeycombing, basal/peripheral, reticular, traction bronchiectasis
• Treatment: antifibrotics (pirfenidone, nintedanib) reduce FVC decline by 50%
• Prognosis: median survival 3-5 years; improved with antifibrotics

Evidence to Quote:

• ASCEND trial: pirfenidone 45% reduction in FVC decline
• INPULSIS trials: nintedanib 50% reduction in FVC decline
• PANTHER-IPF: triple therapy (steroid/azathioprine/NAC) harmful — do not use

Common Mistakes

❌ Mistakes That Fail Candidates:

1. Prescribing steroids for stable IPF — No benefit; PANTHER-IPF showed harm with immunosuppression

2. Missing CTD-ILD — Always exclude with autoantibody screen; management differs

3. Waiting to start antifibrotics — "Watchful waiting" loses irreplaceable lung function; start at diagnosis

4. Not referring for transplant early — Waiting lists are long; refer when FVC less than 80% or declining

5. Confusing UIP and NSIP — UIP has honeycombing and temporal heterogeneity; NSIP has ground-glass predominance and better prognosis

6. Missing acute exacerbation — Rapid worsening over days-weeks; new ground-glass on HRCT; 50% mortality

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12. Special Populations

Elderly Patients (> 75 years)

• Highest incidence age group
• Antifibrotics effective and generally well-tolerated
• Transplantation limited by age criteria
• Focus on quality of life and symptom control
• Advance care planning essential

Combined Pulmonary Fibrosis and Emphysema (CPFE)

• Emphysema (upper zones) + fibrosis (lower zones)
• Spirometry may appear "preserved" (emphysema counterbalances restriction)
• DLCO severely reduced (both contribute)
• Very high risk of pulmonary hypertension (> 50%)
• Worse prognosis than IPF alone
• Limited data on antifibrotic efficacy

Familial IPF

• ≥2 first-degree relatives with ILD
• Earlier age of onset (50s)
• Often telomere-related mutations (TERT, TERC)
• Genetic counselling recommended
• Consider telomere length testing
• Extra-pulmonary manifestations (liver disease, bone marrow failure)

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13. Guidelines Summary

Major Guidelines

Key Recommendations Summary

Diagnosis:

1. HRCT essential for all suspected ILD
2. Definite UIP pattern + exclusion of causes = IPF diagnosis (no biopsy needed)
3. Multidisciplinary discussion for all ILD diagnoses
4. Surgical lung biopsy only if HRCT indeterminate and diagnosis needed

Treatment:

1. Antifibrotic therapy (pirfenidone OR nintedanib) for all IPF patients
2. Start early — do not wait for progression
3. Pulmonary rehabilitation for all suitable patients
4. Supplemental oxygen if hypoxic
5. Early transplant referral in suitable candidates
6. Integrate palliative care from diagnosis

What NOT to Do:

• Do not use corticosteroids for stable IPF
• Do not use immunosuppressive agents
• Do not use warfarin
• Do not delay treatment initiation

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14. Patient and Layperson Explanation

What is Idiopathic Pulmonary Fibrosis (IPF)?

Idiopathic Pulmonary Fibrosis is a condition where the lungs gradually become scarred (fibrosed) for reasons we don't fully understand (hence "idiopathic"). This scarring makes the lungs stiff and less able to transfer oxygen into the blood, causing breathlessness.

Why Does It Matter?

IPF is a serious, life-changing diagnosis. It is a progressive condition, meaning it tends to get worse over time. Average survival is 3-5 years from diagnosis, though this varies considerably — some people live much longer, especially with treatment.

The good news is that treatments are now available that can slow down the disease. The earlier treatment starts, the better.

What Are the Symptoms?

• Breathlessness: Usually starts gradually, first noticed during exercise, then progressively worsens
• Dry cough: Persistent and often frustrating
• Tiredness: Common and can be significant
• Crackling sounds: Your doctor may hear "crackles" when listening to your lungs
• Clubbing: Some people develop widening of the fingertips

How Is It Diagnosed?

1. Listening to your chest: Doctors can often hear characteristic "Velcro-like" crackles
2. CT scan of the lungs: A detailed scan that shows the scarring pattern
3. Breathing tests: Measure how well your lungs are working
4. Blood tests: To rule out other conditions

What Treatment Is Available?

Antifibrotic Medications:

• Two tablets are available: pirfenidone and nintedanib
• They slow down the scarring process by about half
• They don't cure IPF or reverse existing scarring, but they help preserve your lung function for longer
• Side effects include stomach upset and (for pirfenidone) sensitivity to sunlight

Supportive Care:

• Pulmonary rehabilitation: Exercise programmes to keep you as active as possible
• Oxygen therapy: If your oxygen levels become low
• Vaccinations: To protect against infections

Lung Transplant:

• For some patients, a lung transplant may be considered
• Not everyone is suitable, but it should be discussed early

Palliative Care:

• Specialists who help manage symptoms and support you and your family
• Involved early alongside other treatments, not just at the end

What Can You Do?

1. Stop smoking (if you smoke)
2. Take your medications as prescribed
3. Stay active — exercise helps maintain function
4. Attend pulmonary rehabilitation
5. Get vaccinated — flu, pneumonia, COVID
6. Report worsening symptoms promptly

When to Seek Urgent Help

Contact your team or seek medical attention if:

• Your breathlessness suddenly gets much worse
• You develop a fever or feel unwell
• You cough up blood
• Your oxygen levels drop significantly
• You develop swelling in your legs

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15. References

Primary Guidelines

1. Raghu G, Remy-Jardin M, Myers JL, et al. Diagnosis of Idiopathic Pulmonary Fibrosis. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. doi:10.1164/rccm.201807-1255ST PMID: 30168753

2. Raghu G, Remy-Jardin M, Richeldi L, et al. Idiopathic Pulmonary Fibrosis (an Update) and Progressive Pulmonary Fibrosis in Adults: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2022;205(9):e18-e47. doi:10.1164/rccm.202202-0399ST PMID: 35486072

Epidemiology and Prognosis

3. Ley B, Collard HR, King TE Jr. Clinical course and prediction of survival in idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2011;183(4):431-440. doi:10.1164/rccm.201006-0894CI PMID: 20935110

Pathophysiology

4. Martinez FJ, Collard HR, Pardo A, et al. Idiopathic pulmonary fibrosis. Nat Rev Dis Primers. 2017;3:17074. doi:10.1038/nrdp.2017.74 PMID: 29052582

Landmark Treatment Trials

5. King TE Jr, Bradford WZ, Castro-Bernardini S, et al. A phase 3 trial of pirfenidone in patients with idiopathic pulmonary fibrosis (ASCEND). N Engl J Med. 2014;370(22):2083-2092. doi:10.1056/NEJMoa1402582 PMID: 24836312

6. Richeldi L, du Bois RM, Raghu G, et al. Efficacy and safety of nintedanib in idiopathic pulmonary fibrosis (INPULSIS). N Engl J Med. 2014;370(22):2071-2082. doi:10.1056/NEJMoa1402584 PMID: 24836310

Transplantation

7. Weill D, Benden C, Corris PA, et al. A consensus document for the selection of lung transplant candidates: 2014--an update from the Pulmonary Transplantation Council of the International Society for Heart and Lung Transplantation. J Heart Lung Transplant. 2015;34(1):1-15. doi:10.1016/j.healun.2014.06.014 PMID: 25085497

Prognosis

8. Ley B, Ryerson CJ, Vittinghoff E, et al. A multidimensional index and staging system for idiopathic pulmonary fibrosis. Ann Intern Med. 2012;156(10):684-691. doi:10.7326/0003-4819-156-10-201205150-00004 PMID: 22586007

Epidemiology Studies

9. Hutchinson J, Fogarty A, Hubbard R, McKeever T. Global incidence and mortality of idiopathic pulmonary fibrosis: a systematic review. Eur Respir J. 2015;46(3):795-806. doi:10.1183/09031936.00185114 PMID: 25976683

10. Raghu G, Chen SY, Hou Q, et al. Incidence and prevalence of idiopathic pulmonary fibrosis in US adults 18-64 years old. Eur Respir J. 2016;48(1):179-186. doi:10.1183/13993003.01653-2015 PMID: 27126689

Risk Factors

11. Baumgartner KB, Samet JM, Stidley CA, et al. Cigarette smoking: a risk factor for idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 1997;155(1):242-248. doi:10.1164/ajrccm.155.1.9001319 PMID: 9001319

12. Lee JS, Ryu JH, Elicker BM, et al. Gastroesophageal reflux therapy is associated with longer survival in patients with idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2011;184(12):1390-1394. doi:10.1164/rccm.201101-0138OC PMID: 21700913

Genetics

13. Seibold MA, Wise AL, Speer MC, et al. A common MUC5B promoter polymorphism and pulmonary fibrosis. N Engl J Med. 2011;364(16):1503-1512. doi:10.1056/NEJMoa1013660 PMID: 21506741

Negative Trials (Important for Examination)

14. Raghu G, Anstrom KJ, King TE Jr, et al. Prednisone, azathioprine, and N-acetylcysteine for pulmonary fibrosis (PANTHER-IPF). N Engl J Med. 2012;366(21):1968-1977. doi:10.1056/NEJMoa1113354 PMID: 22607134

NICE Guidance

15. National Institute for Health and Care Excellence. Idiopathic pulmonary fibrosis in adults: diagnosis and management (NG163). 2017. Available at: https://www.nice.org.uk/guidance/ng163

Other Negative Trials

16. Noth I, Anstrom KJ, Calvert SB, et al. A placebo-controlled randomized trial of warfarin in idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2012;186(1):88-95. doi:10.1164/rccm.201202-0314OC PMID: 22561965

17. Zisman DA, Schwarz M, Anstrom KJ, et al. A controlled trial of sildenafil in advanced idiopathic pulmonary fibrosis. N Engl J Med. 2010;363(7):620-628. doi:10.1056/NEJMoa1002110 PMID: 20484178

Pulmonary Rehabilitation

18. Dowman L, Hill CJ, Holland AE. Pulmonary rehabilitation for interstitial lung disease. Cochrane Database Syst Rev. 2014;(10):CD006322. doi:10.1002/14651858.CD006322.pub3 PMID: 25284270

Transplantation Guidelines

19. Leard LE, Holm AM, Valapour M, et al. Consensus document for the selection of lung transplant candidates: An update from the International Society for Heart and Lung Transplantation. J Heart Lung Transplant. 2021;40(7):573-612. doi:10.1016/j.healun.2021.03.005 PMID: 33985894

HRCT Criteria

20. Lynch DA, Sverzellati N, Travis WD, et al. Diagnostic criteria for idiopathic pulmonary fibrosis: a Fleischner Society White Paper. Lancet Respir Med. 2018;6(2):138-153. doi:10.1016/S2213-2600(17)30433-2 PMID: 29154106

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate guidelines and specialists for patient care.