What are the diagnostic criteria and treatment options for idiopathic pulmonary fibrosis (IPF)?

Diagnosis and Treatment of Idiopathic Pulmonary Fibrosis (IPF)

The diagnosis of IPF requires a multidisciplinary approach involving pulmonologists, radiologists, and pathologists to identify a usual interstitial pneumonia (UIP) pattern on high-resolution computed tomography (HRCT) or lung biopsy, after excluding other known causes of interstitial lung disease. 1

Diagnostic Criteria for IPF

Essential Diagnostic Requirements

• Exclusion of other known causes of interstitial lung disease (ILD), including environmental exposures, drug toxicity, and connective tissue diseases 1
• PLUS either:
  • Presence of UIP pattern on HRCT (without need for lung biopsy) 1
  • OR specific combinations of HRCT patterns and histopathology patterns in patients who undergo lung biopsy 1

HRCT Patterns for IPF Diagnosis

• UIP Pattern (all four features required): 1

  • Subpleural, basal predominance
  • Reticular abnormality
  • Honeycombing with or without traction bronchiectasis
  • Absence of features inconsistent with UIP pattern

• Possible UIP Pattern (all three features required): 1

  • Subpleural, basal predominance
  • Reticular abnormality
  • Absence of features inconsistent with UIP pattern

• Inconsistent with UIP Pattern (any of these features): 1

  • Upper or mid-lung predominance
  • Peribronchovascular predominance
  • Extensive ground-glass abnormality (extent > reticular abnormality)
  • Profuse micronodules
  • Discrete cysts (away from areas of honeycombing)
  • Diffuse mosaic attenuation/air-trapping
  • Consolidation in bronchopulmonary segment(s)/lobe(s)

Histopathology Patterns

• Surgical lung biopsy findings should be categorized as "UIP," "probable UIP," "indeterminate for UIP," or "alternative diagnosis" 1
• Key histologic features of UIP include patchy fibrosis, fibroblastic foci, and honeycombing 1

Clinical Evaluation

Clinical Presentation

• Most common in older adults (sixth and seventh decades) 1
• Male predominance 1
• History of cigarette smoking in majority of patients 1
• Insidious onset of dyspnea and dry cough 1, 2
• Bibasilar inspiratory crackles on auscultation 1
• Finger clubbing in <50% of cases 1, 2

Laboratory Evaluation

• Recommended laboratory tests: 1
  • Complete blood count, C-reactive protein, serum creatinine, liver function tests
  • Autoimmune serologies: anti-nuclear antibodies, rheumatoid factor, anti-citrullinated cyclic peptide antibodies
  • Additional testing based on clinical suspicion: anti-SSA/SSB, anti-centromere, anti-topoisomerase-1, anti-synthetase antibodies

Bronchoalveolar Lavage (BAL)

• Recommended when diagnosis is uncertain, especially if HRCT does not show definite UIP pattern 1
• Typical findings in IPF: increased neutrophils with some eosinophils 1
• Lymphocytosis >30% suggests alternative diagnoses like hypersensitivity pneumonitis 1

Pulmonary Function Tests

• Restrictive pattern with reduced vital capacity (VC) and increased FEV1/FVC ratio 1, 2
• Impaired gas exchange (increased A-a gradient or decreased DLCO) 1, 2
• Serial changes in FVC predict mortality 2

Diagnostic Algorithm

1. Initial Assessment: Evaluate for risk factors and exclude other causes of ILD 1
2. HRCT Evaluation: Determine if pattern is UIP, possible UIP, or inconsistent with UIP 1
3. Decision for Lung Biopsy: 1
   • If HRCT shows definite UIP pattern: No biopsy needed, diagnose IPF
   • If HRCT shows possible UIP or indeterminate pattern: Consider surgical lung biopsy
   • If HRCT is inconsistent with UIP: Consider alternative diagnoses
4. Multidisciplinary Discussion: Integrate clinical, radiological, and pathological findings 1

Treatment Options

Pharmacological Therapy

• Antifibrotic medications are the mainstay of treatment: 3, 4, 5

  • Pirfenidone: Slows decline in FVC, reduces disease progression
  • Nintedanib: Slows decline in FVC, may prevent acute exacerbations

• NOT recommended: 1, 4

  • Triple therapy with prednisone, azathioprine, and N-acetylcysteine

Non-Pharmacological Management

• Pulmonary rehabilitation improves quality of life and functional capacity 4, 5
• Supplemental oxygen for hypoxemia 5
• Management of comorbidities (GERD, sleep apnea, pulmonary hypertension) 4

Lung Transplantation

• Only treatment shown to increase life expectancy 5
• Should be considered for patients with progressive disease who meet established criteria 1

Disease Monitoring

• Regular assessment of symptoms, particularly worsening dyspnea 6
• Serial pulmonary function tests (FVC, DLCO) 6, 2
• 6-minute walk test to evaluate functional capacity 2
• Follow-up HRCT to assess disease progression 6
• Evaluation for pulmonary hypertension with echocardiography 7, 6

Pitfalls to Avoid

• Misdiagnosing IPF without adequate multidisciplinary discussion 1, 6
• Initiating treatment before establishing a specific diagnosis 6
• Overlooking connective tissue disease as a potential cause of ILD 1, 6
• Failing to recognize disease progression during follow-up 6
• Delaying referral to specialized centers for complex cases 6