Introduction Pirfenidone has undergone NICE approval and is recommended for patients with IPF if the FVC is 50–80% 1. We hypothesised that the NICE guidance would disadvantage a significant cohort of IPF patients who have moderate reduction in transfer factor despite preserved FVC.

Methods We retrospectively reassessed the eligibility of fifty IPF patients on the named patient programme using the NICE guidance. Electronic CT and clinical reports were analysed for the presence of coexisting emphysema.

Results Of fifty patients we identified that 20/50 (40%) would not have been prescribed pirfenidone as per the NICE criteria. The average FVC was significantly higher in the 20 patients that did not meet the NICE criteria compared to those that did (97.6 ± 16.24% vs. 65.48 ± 8.56% (p < 0.001) respectively. In contrast there was no difference in transfer factor between the two groups (42.35 ± 14.66% vs. 44.74 ± 12.29%) respectively.

The frequency of emphysema was statistically different between those that met the NICE criteria and those that did not (3 vs. 8 p = 0.0409). Of those patients that had an FVC greater than 80%, 12/20 (60%) had no emphysema visible on CT imaging and 2 (10%), 4 (20%) and 2 (10%) had evidence of mild, moderate and severe emphysema respectively. However, the average transfer factor was not significantly different between those with or without emphysema (35.75% vs. 46.75% respectively).

Conclusion This retrospective data demonstrates that the sole use of FVC in the NICE criteria for treating IPF disadvantages 40% of patients who demonstrate a significant reduction in transfer factor despite FVC greater than 80%. In this study this reduced transfer factor and preserved FVC can only be attributed to the presence of coexisting emphysema in 8/20 (40%) of patients. 60% of patients had IPF alone with FVC greater than 80% despite an average transfer factor of 47%, which was not statistically different to those with coexisting emphysema. We would therefore advocate the use of both FVC and DLCO when assessing patient suitability for pirfenidone treatment for IPF. The use of FVC alone excludes a substantial cohort of IPF patients who have preserved FVC, reduced DLCO with or without coexisting emphysema.