Assessment of survival in patients with idiopathic pulmonary fibrosis using quantitative HRCT indexes

Sebastiano Emanuele Torrisi; Stefano Palmucci; Alessandro Stefano; Giorgio Russo; Alfredo Gaetano Torcitto; Daniele Falsaperla; Mauro Gioè; Mauro Pavone; Ada Vancheri; Gianluca Sambataro; Domenico Sambataro; Letizia Antonella Mauro; Emanuele Grassedonio; Antonio Basile; Carlo Vancheri

doi:10.1186/s40248-018-0155-2

Assessment of survival in patients with idiopathic pulmonary fibrosis using quantitative HRCT indexes

Multidiscip Respir Med. 2018 Dec 1:13:43. doi: 10.1186/s40248-018-0155-2. eCollection 2018.

Authors

Sebastiano Emanuele Torrisi^#¹, Stefano Palmucci^#², Alessandro Stefano³, Giorgio Russo³, Alfredo Gaetano Torcitto², Daniele Falsaperla², Mauro Gioè⁴, Mauro Pavone¹, Ada Vancheri¹, Gianluca Sambataro^{1

5}, Domenico Sambataro⁵, Letizia Antonella Mauro², Emanuele Grassedonio⁶, Antonio Basile², Carlo Vancheri¹

Affiliations

¹ 1Regional Referral Centre for Rare Lung Diseases, A.O.U. Policlinico-Vittorio Emanuele, Department of Clinical and Experimental Medicine, University of Catania, via Santa Sofia 78, Catania, Italy.
² 2Radiology I Unit, Department of Medical Surgical Sciences and Advanced Technologies, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
³ 3National Research Council (IBFM-CNR), Contrada Pietropollastra-Pisciotta, Institute of Molecular Bioimaging and Physiology, 90015 Cefalù, Italy.
⁴ 4Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.
⁵ Artroreuma srl, Outpatient of Rheumatology Accredited with National Health System, Corso San Vito 53, 95030 Mascalucia, CT Italy.
⁶ 6Section of Radiological Sciences, DIBIMEF, University Hospital "Paolo Giaccone", University of Palermo, Palermo, Italy.

^# Contributed equally.

Abstract

Background: The assessment of Idiopathic Pulmonary Fibrosis (IPF) using HRCT requires great experience and is limited by a significant inter-observer variability, even between trained radiologists. The evaluation of HRCT through automated quantitative analysis may hopefully solve this problem. The accuracy of CT-histogram derived indexes in the assessment of survival in IPF patients has been poorly studied.

Methods: Forty-two patients with a diagnosis of IPF and a follow up time of 3 years were retrospectively collected; HRCT and Pulmonary Function Tests (PFTs) performed at diagnosis time were analysed; the extent of fibrotic disease was quantified on HRCT using kurtosis, skewness, Mean Lung Density (MLD), High attenuation areas (HAA%) and Fibrotic Areas (FA%). Univariate Cox regression was performed to assess hazard ratios for the explored variables and a multivariate model considering skewness, FVC, DL_CO and age was created to test their prognostic value in assessing survival. Through ROC analysis, threshold values demonstrating the best sensitivity and specificity in predicting mortality were identified. They were used as cut-off points to graph Kaplan-Meier curves specific for the CT-indexes.

Results: Kurtosis, skewness, MLD, HAA% and FA% were good predictors of mortality (HR 0.44, 0.74, 1.01, 1.12, 1.06; p = 0.03, p = 0.01, p = 0.02, p = 0.02 and p = 0.017 respectively). Skewness demonstrated the lowest Akaike's information criterion value (55.52), proving to be the best CT variable for prediction of mortality. Significant survival differences considering proposed cut-off points were also demonstrated according to kurtosis (p = 0.02), skewness (p = 0.005), MLD (p = 0.003), HAA% (p = 0.009) and FA% (p = 0.02) - obtained from quantitative HRCT analysis at diagnosis time.

Conclusions: CT-histogram derived indexes may provide an accurate estimation of survival in IPF patients. They demonstrate a correlation with PFTs, highlighting their possible use in clinical practice.

Keywords: HRCT; Idiopathic pulmonary fibrosis; Kurtosis; Mortality; Survival; Usual interstitial pneumonia.