A 20% reduction in the FEV1 from baseline is what is used to define the development of BOS post lung transplant (LTx). Patient baseline is defined by the average of the two highest FEV1’s at least 3 weeks apart post-LTx. Patients may establish different baselines based on as yet undetermined factors. We sought to determine whether the baseline established has any influence on the subsequent incidence of BOS and survival post-transplant.
Baseline FEV1’s of all COPD and IPF SLTx recipients transplanted between March 1997 and November 2001 were determined. In each patient, these were compared to the maximal attainable FEV1 (MAFEV1) as determined from: residual native lung function plus predicted allograft function based on recipient characteristics. The incidence of BOS was then compared between those patients who established a baseline >80% of MAFEV1 to those whose baseline was<80% of the MAFEV1.
There were 23 COPD and 23 IPF patients included in the analysis. IPF patients tended to establish baselines that were closer to the MAFEV1 compared to COPD patients (85.8% vs. 76.6%, p<0.06). There was a trend for IPF patients taking longer to reach their first highest FEV1 compared to COPD patients (249 vs 168 days, p<0.28). Patients with baseline FEV1s 80% had a trend to a greater propensity for BOS (33.2% vs.18.2%, p<0.24), while survival in the two groups was similar (77% vs. 79%, p=0.89).
IPF patients may have higher baseline FEV1’s than COPD patients. This could represent influence of the native lung on allograft emptying in the COPD patients or a greater contribution from the native lung in IPF patients. The longer time interval to establish a baseline in IPF patients is of uncertain significance.
The trend towards a higher baseline influencing the subsequent development of BOS may have important clinical implications.
S.D. Nathan, None.