. 2011 Apr 19;32(2):311–326. doi: 10.1016/j.ccm.2011.02.009

Table 1.

Bronchiolitis obliterans syndrome classification system

	1993 Classification	2002 Classification
	FEV₁ 80% or more of baseline	FEV₁ >90% of baseline and FEF_25-75 >75% of baseline	BOS 0
	FEV₁ 80% or more of baseline	FEV₁ 81% to 90% of baseline and/or FEF_25-75 = or <75% of baseline	BOS 0-p
BOS 1	FEV₁ 66% to 80% of baseline	FEV₁ 66% to 80% of baseline	BOS 1
BOS 2	FEV₁ 51% to 65% of baseline	FEV₁ 51% to 65% of baseline	BOS 2
BOS 3	FEV₁ 50% or less of baseline	FEV₁ 50% or less of baseline	BOS 3

Data from Estenne M, Maurer JR, Boehler A, et al. Bronchiolitis obliterans syndrome 2001: an update of the diagnostic criteria. J Heart Lung Transplant 2002;21:297–310.