Hepatitis C virus enhances incidence of idiopathic pulmonary fibrosis

Table 1 Diagnostic criteria of IPF

Number	Criteria
Major criteria 1	Exclusion of other known caused of interstitial lung disease, such as certain drug toxicities, environmental exposures, and connective tissue diseases
Major criteria 2	Abnormal pulmonary function studies that include evidence of restriction (reduced breathing vital capacity) and impaired gas exchange (increased AaPO2 with rest or after exercising or decreased diffusion lung capacity)
Major criteria 3	Bibasilar reticular abnormalities with minimal ground glass opacities on conventional chest radiographs or high-resolution computed tomography scans
Major criteria 4	Histological lung examination or bronchoalveolar lavage showing no features to support an alternative diagnosis
Minor criteria 1	Age > 50 yr
Minor criteria 2	Insidious onset of otherwise unexplained dyspnea on exertion
Minor criteria 3	Duration of illness ≥ 3 mo
Minor criteria 4	Bibasilar, inspiratory crackles (dry or “Velcro” type in quality)