Methods Gender, age, smoking history, presence of emphysema on HRCT thorax and echocardiogram confirmed pulmonary hypertension were collected retrospectively from 253 IPF patients (in accordance with ATS/ERS criteria and MDT consensus) from a single centre in the UK between 19^th April 2007 and 13^th November 2014. Lung function including FEV₁, FVC, DLco and 6 minute walk test (distance, resting and minimum oxygen saturation and maximum heart rate) were collected at baseline, 6 and 12 months of follow up. Survival data were censored at 1^st January 2016. The relationship between GAP or CPI and survival was analysed by Spearman’s correlation, ROC area under the curve and Chi² analysis. Multivariate analysis and linear regression were used for the modelling.

Results Of the 253 patients included 188 were male (74%) with age 71.4 ± 8.3 years (mean ± SD). There were 164 (64.8%) ex-smokers and 12 (4.7%) current smokers. At presentation 19 patients had pulmonary hypertension and 35 had evidence of emphysema on HRCT thorax. Baseline lung function FEV₁ 79 ± 22% predicted, FVC 82 ± 19% predicted, DLco 45 ± 15% predicted (mean ± SD). Median survival was 1169 days (3.2 years). The association between survival and CPI (r² 0.59, p < 0.01) or GAP (r² 0.45, p < 0.01) was modest. However ROC curve analysis demonstrated that GAP and CPI were poor predictors of survival. Chi² analysis shows there is no significant difference between these scoring systems. Multivariate analysis demonstrated that baseline% predicted DLco (r² = 0.32, p = 6×10^–20) (Figure 1) had the strongest association with survival.

Conclusion Our data suggest that baseline percent predicted DLco may be a better predictor of outcome in patients with IPF. These results required validation by an independent cohort.

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Abstract S21 Figure 1