Table 2. 2002 American Thoracic Society/European Respiratory Society criteria for the diagnosis of idiopathic pulmonary fibrosis
Major criteria
    Exclusion of other known causes of ILD, such as certain drug toxicities, environmental exposures and connective tissue diseases
    Abnormal pulmonary function studies that include evidence of restriction (reduced VC, often with an increased FEV1/FVC ratio) and impaired gas exchange (increased PA–aO2, decreased PaO2 with rest or exercise, or decreased DLCO)
    Bibasilar reticular abnormalities with minimal ground-glass opacities on HRCT
    Transbronchial lung biopsy or BAL showing no features to support an alternative diagnosis
Minor criteria
    Age >50 years
    Insidious onset of otherwise unexplained dyspnoea on exertion
    Duration of illness >3 months
    Bibasilar, inspiratory crackles (dry or “Velcro”-type in quality)
  • In the immunocompetent adult, the presence of all of the major diagnostic criteria as well as at least three of the four minor criteria increases the likelihood of a correct clinical diagnosis of idiopathic pulmonary fibrosis. See figure 2 for the updated 2011 criteria. ILD: interstitial lung disease; VC: vital capacity; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; PA–aO2: alveolar–arterial oxygen tension difference; PaO2: arterial oxygen tension; DLCO: diffusing capacity of the lung for carbon monoxide; HRCT: high-resolution computed tomography; BAL: bronchoalveolar lavage. Data from [10].