Table 2 ATS/ERS criteria for diagnosis of idiopathic pulmonary fibrosis (IPF) in the absence of surgical lung biopsy*†
Major criteriaMinor criteria
  • Exclusion of other known causes of ILD such as certain drug toxicities, environmental exposures and connective tissue diseases

  • Age >50 years

  • Abnormal pulmonary function studies that include evidence of restriction (reduced VC, often with an increased FEV1/FVC ratio) and impaired gas exchange (increased P(A–a)o2, decreased Pao2 with rest or exercise or decreased Tlco)

  • Bibasilar, inspiratory crackles (dry or “Velcro”-type in quality)

  • Bibasilar reticular abnormalities with minimal ground glass opacities on HRCT scans

  • Insidious onset of otherwise unexplained dyspnoea on exertion

  • Transbronchial lung biopsy or BAL showing no features to support an alternative diagnosis‡

  • Duration of illness >3 months

  • BAL, bronchoalveolar lavage; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; HRCT, high resolution computed tomography; ILD, interstitial lung disease; P(A–a)o2, difference between alveolar and arterial pressure; Pao2, arterial oxygen tension; Tlco, carbon monoxide transfer factor; VC, vital capacity.

  • *Modified from American Thoracic Society/European Respiratory Society recommendations.2

  • †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 IPF.

  • ‡The requirement for transbronchial lung biopsy/bronchoalveolar lavage within the diagnostic criteria for IPF is currently under review.