Idiopathic pulmonary fibrosis

Overview

IPF is the most common ILD in the UK - a chronic, progressive interstitial fibrosis with no identifiable cause. Median survival 3-5 years from diagnosis. Histological pattern: usual interstitial pneumonia (UIP).

Risk factors

•Age >50 (peak 70+), male (2:1), current or ex-smoker (~two-thirds of cases)

Presentation

•Progressive exertional dyspnoea - cardinal symptom; insidious onset over months to years

•Dry, persistent cough - non-productive

•Bibasal fine end-inspiratory crackles - 'Velcro-like'; lower lobe and peripheral predominance (UIP pattern)

•Finger clubbing - ~50% of patients

•Cor pulmonale (raised JVP, peripheral oedema, loud P2) - late sign of pulmonary hypertension

⚠️

Upper lobe crackles should prompt consideration of an alternative diagnosis (sarcoidosis, hypersensitivity pneumonitis) - IPF affects lower lobes and periphery.

Investigations

🏆 Gold standard

•HRCT chest - bilateral, basal, peripheral honeycombing ± traction bronchiectasis (UIP pattern); typical HRCT in right clinical context does not require biopsy

•Chest X-ray - bilateral lower zone reticulonodular shadowing, reduced lung volumes

•Spirometry - restrictive pattern: reduced FVC, reduced TLC, normal or elevated FEV1:FVC ratio (>0.7)

•Transfer factor (TLCO/DLCO) - reduced; often disproportionately low relative to spirometry; sensitive early marker

•ABG - type 1 respiratory failure initially; type 2 is a late, pre-terminal finding

•Bloods - ANA positive ~30%, RF positive ~10%; consider secondary causes if positive

•BAL - not diagnostic; lymphocytosis suggests hypersensitivity pneumonitis rather than IPF

•Surgical lung biopsy - reserved for atypical/indeterminate HRCT findings where result would change management

Management

🥇 First-line

•smoking cessation and pulmonary rehabilitation - essential regardless of stage

•Antifibrotics (first-line):

•Pirfenidone - inhibits fibroblast proliferation and collagen synthesis; slows FVC decline; licensed for FVC 50-80% predicted

•Nintedanib - tyrosine kinase inhibitor (VEGFR, FGFR, PDGFR); slows FVC decline; licensed for FVC ≥50% predicted

•LTOT - resting PaO2 ≤7.3 kPa, or ≤8 kPa with complications (polycythaemia, pulmonary hypertension); consider ambulatory oxygen for exercise-induced desaturation

•Antireflux treatment - lansoprazole or omeprazole; GERD common and microaspiration may accelerate progression

•Palliation of breathlessness - low-dose morphine for refractory dyspnoea; lorazepam for anxiety; early specialist palliative care

•Lung transplantation - only definitive treatment; refer if age <65, no active malignancy, no significant comorbidity; limited by organ availability

🚨

Steroids and immunosuppressants are NOT recommended in IPF. The PANTHER-IPF trial showed triple therapy (prednisolone, azathioprine, N-acetylcysteine) increased mortality compared to placebo. Steroids work in NSIP and hypersensitivity pneumonitis but cause harm in IPF.

Complications

•Acute exacerbation of IPF - sudden unexplained worsening of dyspnoea within 30 days; new bilateral ground-glass opacities on HRCT; very high short-term mortality

•Pulmonary hypertension and cor pulmonale - fibrosis obliterates pulmonary vasculature → raised PVR → right heart failure

•Lung cancer - significantly increased risk (particularly squamous cell and adenocarcinoma)

•Respiratory failure - type 1 initially, progressing to type 2 in end-stage disease

Prognosis

•Median survival ~3-5 years from diagnosis

•Antifibrotics slow FVC decline but have not been shown to improve overall survival in RCTs

•Worse prognosis: severe dyspnoea, low baseline FVC/DLCO, extensive honeycombing, exercise desaturation, pulmonary hypertension, acute exacerbations