Disease extent | Limited | Extensive |
---|---|---|
Limited disease: forced vital capacity (FVC) greater than 50Â % predicted and gas transfer (TLCO) greater than 40Â % predicted | Extensive disease: FVC less than 50Â % or TLCO less than 40Â % predicted | |
Disease behaviour | Stable | Progressive |
Stable disease: a decline of less than 10Â % in FVC or less than 15Â % in TLCO in the previous 12Â months | Progressive disease: a decline in either FVC greater than 10Â % or TLCO greater than 15Â % during the previous 12Â months |