IC4: a new combined predictive index of mortality in idiopathic pulmonary fibrosis

BACKGROUND While a number of individual patient characteristics are associated with survival in idiopathic pulmonary fibrosis (IPF), their incorporation into combined indexes, such as the GAP index, has been shown to increase the predictive capacity. It is unknown whether the predictive capacity of GAP-derived indexes that also include anthropometric and exercise parameters is superior to the original instrument. METHODS We tested the four-year survival predictive capacity of a modified, adimensional and multiplicative GAP index (IC4) that included percent forced vital capacity (FVC%), diffusing capacity of the lung for carbon monoxide (DLCO%), body mass index (BMI), and six-minute walk distance (6MWD) in 90 IPF patients recruited from two centres in France and Italy. RESULTS In ROC comparisons, the AUC of the IC4 (0.859, 95% CI 0.770-0.924 p