Mortality prediction in idiopathic pulmonary fibrosis: evaluation of computer-based CT analysis with conventional severity measures

Abstract

Computer-based computed tomography (CT) analysis can provide objective quantitation of disease in idiopathic pulmonary fibrosis (IPF). A computer algorithm, CALIPER, was compared with conventional CT and pulmonary function measures of disease severity for mortality prediction.CT and pulmonary function variables (forced expiratory volume in 1 s, forced vital capacity, diffusion capacity of the lung for carbon monoxide, transfer coefficient of the lung for carbon monoxide and composite physiologic index (CPI)) of 283 consecutive patients with a multidisciplinary diagnosis of IPF were evaluated against mortality. Visual and CALIPER CT features included total extent of interstitial lung disease, honeycombing, reticular pattern, ground glass opacities and emphysema. In addition, CALIPER scored pulmonary vessel volume (PVV) while traction bronchiectasis and consolidation were only scored visually. A combination of mortality predictors was compared with the Gender, Age, Physiology model.On univariate analyses, all visual and CALIPER-derived interstitial features and functional indices were predictive of mortality to a 0.01 level of significance. On multivariate analysis, visual CT parameters were discarded. Independent predictors of mortality were CPI (hazard ratio (95% CI) 1.05 (1.02-1.07), p<0.001) and two CALIPER parameters: PVV (1.23 (1.08-1.40), p=0.001) and honeycombing (1.18 (1.06-1.32), p=0.002). A three-group staging system derived from this model was powerfully predictive of mortality (2.23 (1.85-2.69), p<0.0001).CALIPER-derived parameters, in particular PVV, are more accurate prognostically than traditional visual CT scores. Quantitative tools such as CALIPER have the potential to improve staging systems in IPF.

Predicting Outcomes in Idiopathic Pulmonary Fibrosis Using Automated Computed Tomographic Analysis

“…CALIPER CT analysis has been previously described (29,31), and is outlined in the Supplementary appendix.…”

“…New computer algorithms utilising three-dimensional volumetric CT datasets, can quantify parenchymal pattern extents (27,28) and have been shown to better predict survival in various fibrosing lung diseases at baseline, than visual CT scores (29,30). Computer analysis also has the potential to uncover CT features hitherto under-recognised by visual CT analysis that predict mortality in IPF.…”

“…Computer analysis also has the potential to uncover CT features hitherto under-recognised by visual CT analysis that predict mortality in IPF. The quantitation of pulmonary vessels (arteries and veins) and vessel-related structures (perivascular fibrosis)[ Figure 1], which cannot be achieved by the human eye, have been shown to associate strongly with survival in a series of IPF patients (29).…”

Evaluating disease severity in idiopathic pulmonary fibrosis

“…The investigators also found that a novel parameter called pulmonary vessel volume (PVV) had stronger correlations with lung function tests, indicating that it may have potential in assessing disease severity in IPF. The same group demonstrated that CALIPER-derived honeycombing and PVV were more accurate than traditional fibrosis scores in predicting mortality, independent of physiological indices [75]. While quantitative disease assessment in lung fibrosis has been around for some years, its application in monitoring disease in therapeutic trials has recently gained interest.…”

Staging of idiopathic pulmonary fibrosis

“…These difference confirmed both derivation cohort and validation cohort. (Table 1) This index is simple and applicable not only tertiary center but also general hospital (52,53).And GAP index was valuable as a measure of IPF severity (54)(55)(56)(57)(58)(59). Presence of Velcro Crackles is associated with high score of GAP in IPF (60).…”