Idiopathic Pulmonary Fibrosis - Diagnosis

Diagnosis

Diagnosis requires clinical findings compatible with interstitial lung disease in combination with either characteristic radiologic findings or a pathologic diagnosis of UIP on surgical lung biopsy. Generally, lung biopsy is only undertaken when its risks are outweighed by the potential benefits of identifying an alternative, treatable disease process. Establishing the diagnosis of IPF without a lung biopsy has been shown to be reliable when expert clinicians and radiologists concur that the presenting features are typical of IPF. Based on this evidence, the 2002 ATS/ERS Multidisciplinary Consensus Statement on the Idiopathic Interstitial Pneumonias proposed the following criteria for establishing the diagnosis of IPF without a lung biopsy:

Major criteria (all 4 required):

• Exclusion of other known causes of interstitial lung disease (drugs, exposures, connective tissue diseases)
• Abnormal pulmonary function tests with evidence of restriction (reduced vital capacity) and impaired gas exchange (pO₂, p(A-a)O₂, DLCO)
• Bibasilar reticular abnormalities with minimal ground glass on high-resolution CT scans
• Transbronchial lung biopsy or bronchoalveolar lavage (BAL) showing no features to support an alternative diagnosis

Minor criteria (3 of 4 required):

• Age > 50
• Insidious onset of otherwise unexplained exertional dyspnea
• Duration of illness > 3 months
• Bibasilar inspiratory crackles