Nomenclature and Clinical Staging of Chronic Dysfunction in Lung Allografts
Definitions and Recommendations
1. The term bronchiolitis obliterans syndrome will be used to connote graft deterioration secondary to progressive airways disease for which there is no other cause. It is widely presumed, but unproved, that this is a manifestation of chronic rejection
2. The term bronchiolitis obliterans is reserved for histologically proven diagnoses only; the term bronchiolitis obliterans syndrome does not necessarily require histologic confirmation
3. Spirometric measurements are to be made with equipment that conforms to the American Thoracic Society standards for spirometric testing
4. FEV1 measurements used for analysis will be made without the use of an inhaled bronchodilator preceding the study
5. Patients must be 3 months or more after transplantation to be considered evaluable under this system. However, determination of a baseline value can be made from the data obtained within the first 3 months
6. The baseline value, to which subsequent measures are referred, is defined as the average of the two previous highest consecutive measurements being obtained 3 to 6 weeks apart. In some patients, the baseline value will rise over time, especially in the first 6 to 9 months. The highest baseline achieved is used for all subsequent measurements
7. Patients showing a 20% or greater decline from previous baseline studies shall be evaluable only after exclusion of conditions other than deterioration of graft function, such as airway complications, infections, congestive heart failure, reversible airway reactivity, and systemic diseases
8. Because a universal table for converting the absolute value of FEV1 to "percent predicted" does not exist, a fractional decline in the FEV1 should be determined from the absolute values, especially if the pulmonary function data have been obtained from more than one center
9. For the purposes of staging, a significant decline in the FEV1 will be determined by the average of two measurements made at least 1 month apart. Patient's having a single measurement of decline in FEV1 are not evaluable until a second FEV1 measurement is obtained at least 1 month after the initial data point
10. Fractional decline in the FEV1 shall be expressed as the percent of decline from the previously established baseline. Thus a patient whose previous baseline FEV1 is 2.0 liters, which falls to a value of 1.0 liters (average of two data points at least 1 month apart), shall be construed as having had a 50% factional decline in FEV1. Should this patient's condition temporarily stabilize at the new value and subsequently show a decline in the FEV1 to 800 cc, then the patient, at that point, shall be considered to have suffered a 60% fractional decline in FEV1 (that is, the highest previous baseline value is used for all subsequent calculations)
11. Within each of the four proposed staging catagories, there will be an "a" and a "b" subcategory. These relate to histologic findings on biopsies. The "a" subcatagory shall be used to designate no pathologic evidence of bonchiolitis obliterans (or no pathologic material for evaluation). The "b" subcategory shall be construed to mean that pathologic evidence of obliterative bronchiolitis has been obtained
Staging System
Clinical Stage	Grade of Obliterative Bronciolitis Syndrome	Pathologic Evidence of Obliterative Bronchiolitis
FEV1 80% or more of baseline value	0 (None)	a = No
		b = Yes
FEV1 66% to 80% of baseline value	1 (Mild)	a = No
		b = Yes
FEV1 51% to 65% of baseline value	2 (Moderate)	a = No
		b = Yes
FEV1 50% or less of baseline value	3 (Severe)	a = No
		b = Yes
Reference Cooper JD, et al. A working formulation for the standardization of nomenclature and for clinical staging of chronic dysfunction in lung allografts. J Heart Lung Transplantation 1993;12:713-6.