Introduction Idiopathic Pulmonary Fibrosis (IPF) is a progressive, fatal lung disease with median survival of 3 years (1). NICE has recently approved Pirfenidone, which is the first licensed treatment for IPF. Pirfenidone is licensed for mild to moderate IPF, and the current NICE recommendation is that all patients with FVC (Forced Vital capacity) between 50–80% predicted should be considered for therapy. However, there is no agreed classification of disease severity in IPF. In clinical practice a combination of both FVC and DL_CO (diffusion of lung carbon monoxide) is used to monitor disease progression. We explore the practical impact of using FVC on Pirfenidone prescribing.

Methods 218 incident cases of IPF have been enrolled in a prospective cohort study PROFILE in Central England from September 2009 to June 2013. All patients had a diagnosis of definite or probable IPF based on the ATS consensus 2000. The patients were stratified according to both FVC and DLco. Lung function defects were considered mild (FVC>80%, DL_CO>60%), moderate (FVC 50–80%, DL_CO 40–60%) and severe (FVC<50%, DL_CO <40%).

Results The median age was 72 years with majority cohort males (77% males’ vs 23%females). 181(84%) cases met diagnostic criteria for definite IPF. There was only a moderate correlation between FVC and T_LCO with correlation coefficient = 0.54 and p < 0.001. A total of 79 patients (44%) would be eligible for treatment based on FVC criteria. However, this includes 46 patients (25%) who might be considered to have severe disease based on DLco criteria. (Table 1)

Conclusion Over half our patients eligible for Pirfenidone, based on current NICE criteria, will have severely reduced DL_CO. This highlights the need for an agreed classification of IPF disease severity. Follow up of PROFILE study patients may help guide a classification system.

References

1. Navaratnam et al, Thorax 2011 Jun;66(6):462–7. doi: 10.1136/thoraxjnl-2013-204457.22