Predictive factors of fibrotic interstitial lung abnormality on high-resolution computed tomography scans: a prospective observational study.

Background: Fibrotic types of interstitial lung abnormalities seen on high-resolution computed tomography scans, characterised by traction bronchiolectasis/bronchiectasis with or without honeycombing, are predictors of progression and poor prognostic factors of interstitial lung abnormalities. There are no reports on the clinical characteristics of fibrotic interstitial lung abnormalities on high-resolution computed tomography scans. Therefore, we aimed to examine these clinical characteristics and clarify the predictive factors of fibrotic interstitial lung abnormalities on high-resolution computed tomography scans.
Methods: Clinical and paraclinical data of 164 patients enrolled in the initial year of a multicentre prospective observational study (Kumamoto interstitial lung abnormalities study in Japan) involving over 62,000 examinees during routine health examinations were analysed. Clinical laboratory evaluations are expressed as medians and interquartile ranges for each evaluation time point, and boxplots were created for graphical representation. The percentages of abnormal clinical laboratory results were compared between the groups using chi-square or Fisher's exact tests. Univariate or multivariate logistic regression analyses were performed to analyse the relationship between fibrotic interstitial lung abnormalities and other clinical factors.
Results: Fibrotic interstitial lung abnormalities were observed on high-resolution computed tomography scans in 135 (82%) patients at the time of diagnosis. Multivariate analysis showed that older age (Odds ratio, 1.06; 95% confidence interval, 1.01-1.12; p = 0.021), auscultatory fine crackles (Odds ratio, 3.39; 95% confidence interval, 1.33-8.65; p < 0.01), and elevated serum surfactant protein-D (Odds ratio, 2.68; 95% confidence interval, 1.02-8.64; p = 0.045) were independent predictive factors of fibrotic interstitial lung abnormalities. The predicted area under the curve of the fibrotic interstitial lung abnormalities based on these three factors was 0.77 (95% confidence interval, 0.68-0.86). The proportion of undecided diagnoses in the fibrotic interstitial lung abnormalities group (14%) was significantly lower than that in the non-fibrotic interstitial lung abnormalities group (41%) (p = 0.0027).
Conclusions: Fine crackles on auscultation and elevated serum surfactant protein-D levels are predictors of fibrotic interstitial lung abnormalities in older patients with interstitial lung abnormalities. These findings may assist non-radiological physicians in referring patients to specialists for early intervention in progressive fibrotic interstitial lung diseases.
Trial Registration Number/date: UMIN000045149/2021.12.1.
Competing Interests: Declarations. Ethics approval and consent to participate: This study complied with the Helsinki Declaration and the protocol, and the informed consent forms were approved by the Institutional Review Boards of Kumamoto University Hospital (approval number: 2368), Saiseikai Kumamoto Hospital (approval number: 809), and Kumamoto Red Cross Hospital (approval number: 464). Written informed consent was obtained from all participants. Patient recruitment commenced on 20 June 2022. Consent for publication: Consent for publication was obtained from all participants and authors. Competing interests: KI, HI, TJ, and TS received lecture fees from Nippon Boehringer Ingelheim Co. Ltd. Boehringer Ingelheim had no role in the design, analysis, or interpretation of the results in this study. Boehringer Ingelheim was given the opportunity to review the manuscript for medical and scientific accuracy as it relates to Boehringer Ingelheim substances, as well as intellectual property considerations.KI, KK, YY, KA, HO, KA, NH, KF, TS, JM, MY, and KM declare no conflict of interest.
(© 2025. The Author(s).)