Prognostic value of a composite physiologic index developed by adding bronchial and hyperlucent volumes quantified via artificial intelligence technology.

Background: The composite physiologic index (CPI) was developed to estimate the extent of interstitial lung disease (ILD) in idiopathic pulmonary fibrosis (IPF) patients based on pulmonary function tests (PFTs). The CALIPER-revised version of the CPI (CALIPER-CPI) was also developed to estimate the volume fraction of ILD measured by CALIPER, an automated quantitative CT postprocessing software. Recently, artificial intelligence-based quantitative CT image analysis software (AIQCT), which can be used to quantify the bronchial volume separately from the ILD volume, was developed and validated in IPF. The aim of this study was to develop AIQCT-derived CPI formulas to quantify CT abnormalities in IPF and to investigate the associations of these CPI formulas with survival.
Methods: The first cohort included 116 patients with IPF. In this cohort, ILD, bronchial, and hyperlucent volumes on CT were quantified using AIQCT. New CPI formulas were developed based on PFTs to estimate the volume fraction of ILD (ILD-CPI), the sum of the ILD and bronchial volume fractions (ILDB-CPI), and the sum of the ILD, bronchial and hyperlucent volume fractions (ILDBH-CPI). The associations of the original CPI, the CALIPER-CPI and the AIQCT-derived CPIs with survival were analyzed in the first cohort and in a second cohort of patients with IPF (n = 72).
Results: In the first cohort, over a median observation time of 92.8 months, 79 patients (68.1%) died, and one patient (0.9%) underwent living-donor lung transplantation. The original CPI, the CALIPER-CPI, and all AIQCT-derived CPIs were associated with overall survival (hazard ratios: 1.07-1.22). The C-index of the ILDB-CPI (0.759) was the highest among all AIQCT-derived CPIs and was comparable to that of the original CPI (0.765) and the CALIPER-CPI (0.749). The C-index of the ILDBH-CPI (0.729) was lower than that of the other CPI variables. The second cohort yielded similar C-indices as the first cohort for the original CPI (0.738), CALIPER-CPI (0.757) and ILDB-CPI (0.749).
Conclusions: The ILDB-CPI can predict the outcomes of IPF patients with a similar performance to that of the original CPI and the CALIPER-CPI. Adding the hyperlucent volume to the CPI formula did not improve its predictive accuracy for mortality.
Trial Registration: None (no health care interventions were performed).
Competing Interests: Declarations. Ethics approval and consent to participate: The Institutional Review Board of Kyoto University and the Ethics Committee of Tenri Hospital approved this study (approval numbers R1353, E2119 and No. 635, respectively). The requirement for written informed consent was waived due to the retrospective design of this study. This study was conducted in accordance with the amended Declaration of Helsinki. Consent for publication: Not applicable. Competing interests: Michihiro Uyama has no conflicts of interest; Tomohiro Handa received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited and belongs to an endowed department sponsored by Teijin Pharma Limited; Ryuji Uozumi received personal fees from Daiichi Sankyo, Eisai, Sawai Pharmaceutical, SBI Pharmaceuticals, Statcom and EPS Corporation and lecture fees from Janssen Pharmaceutical and SAS Institute Japan outside the submitted work; Seishu Hashimoto has no conflicts of interest; Yoshio Taguchi has no conflicts of interest; Kohei Ikezoe received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited; Kiminobu Tanizawa received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited; Naoya Tanabe received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited; Tsuyoshi Oguma received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited; Atsushi Matsunashi has no conflicts of interest; Takafumi Niwamoto has no conflicts of interest; Hiroshi Shima has no conflicts of interest; Ryobu Mori has no conflicts of interest; Tomoki Maetani has no conflicts of interest; Yusuke Shiraishi has no conflicts of interest; Tomomi W. Nobashi has no conflicts of interest; Ryo Sakamoto has no conflicts of interest; Takeshi Kubo has no conflicts of interest; Akihiko Yoshizawa has no conflicts of interest; Kazuhiro Terada has no conflicts of interest; Yuji Nakamoto has no conflicts of interest; and Toyohiro Hirai received a research grant from FUJIFILM Corporation and Daiichi Sankyo Company, Limited.
(© 2024. The Author(s).)