The International Society for Heart and Lung Transplantation (ISHLT) defined criteria in 1993 for the bronchiolitis obliterans syndrome (BOS, obliterative bronchiolitis).
Parameters:
(1) current FEV1
(2) baseline FEV1
(3) histopathologic evidence of obliterative bronchiolitis
FEV1 as percent of baseline =
= (current FEV1) / (baseline FEV1) * 100%
FEV1 as Percent of Baseline |
BOS Severity |
Stage |
> 80% |
none or not significant |
0 |
66 - 80% |
mild |
1 |
51 - 65% |
moderate |
2 |
< 50% |
severe |
3 |
where:
• The specifications for Stage 0 was an FEV1 "80% or more" and for Stage "66-80%", with overlap at 80%. Subsequent references indicate 80% is Stage 1.
Histopathologic Evidence of Obliterative Bronchiolitis |
Subcode |
absent |
a |
present |
b |
Specialty: Pulmonology, Surgery, general