Criteria

Diagnostic criteria for idiopathic pulmonary fibrosis[1][5]

Diagnostic criteria for idiopathic pulmonary fibrosis (IPF) have been proposed in joint guidance from the American Thoracic Society (ATS), European Respiratory Society (ERS), Japanese Respiratory Society (JRS), and Latin American Thoracic Association (ALAT).[1][5]

IPF is clinically suspected in the presence of:

  • Unexplained symptomatic or asymptomatic patterns of bilateral pulmonary fibrosis on a chest x-ray or high-resolution computed tomography (HRCT)

  • Bibasilar inspiratory crackles

  • Age greater than 60 years (familial pulmonary fibrosis may rarely present from age 40 years)

The diagnosis of IPF is then based on high-resolution CT (HRCT) and biopsy patterns, in consideration of the following:

  • Exclusion of other known causes of interstitial lung disease (e.g., domestic and occupational environmental exposures, connective tissue disease, and drug toxicity)

  • And the presence of either of

    • A pattern consistent with usual interstitial pneumonia (UIP) on HRCT in patients not subjected to surgical lung biopsy

    • Specific combinations of HRCT and histopathology patterns in patients subjected to surgical lung biopsy

A multidisciplinary approach to diagnosis, involving pulmonologists, radiologists, and pathologists, is of paramount importance to ensure an accurate diagnosis. IPF is the likely diagnosis when a multidisciplinary team agrees to a confident diagnosis of IPF. This may be informed by several findings:

  • Moderate-to-severe traction bronchiectasis/bronchiolectasis identified in men and women older than 50 and 60 years, respectively

  • Extensive (>30%) reticulation present on HRCT in patients older than 70 years

  • Increased neutrophils and/or absent lymphocytosis present in BAL fluid

Diagnostic criteria for acute exacerbation of idiopathic pulmonary fibrosis[15]

Proposed diagnostic criteria for acute exacerbation:

  • Previous or concurrent diagnosis of IPF (Note: if not previously established, this criterion can be met by the presence of radiologic and/or histopathologic changes consistent with UIP at the current exam)

  • Acute worsening or development of dyspnea, typically <1 month duration

  • HRCT with new bilateral ground-glass opacity and/or consolidation superimposed on a background pattern consistent with UIP (Note: the “new” qualifier can be dropped if no previous computed tomography is available)

  • Deterioration not fully explained by cardiac failure or fluid overload

Events that are clinically considered to meet the definition of an acute exacerbation, but where HRCT data are not available, are termed “suspected acute exacerbations.

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