Comparative accuracy of CA-153 and KL-6 as diagnostic and prognostic biomarkers for interstitial lung disease

To discern the potential of KL-6 and CA-153 as diagnostic tools for interstitial lung disease (ILD), understand their relationship with GAP (Gender, Age, and Physiology) stage, and analyze their predictive capacities alongside CT features. This research aims to enhance ILD detection and management in autoimmune patients, emphasizing the diagnostic utility of these biomarkers.

From Mar 2017 to Mar 2024, 398 patients from Taichung Veterans General Hospital's Division of Allergy, Immunology, and Rheumatology with autoimmune diseases were prospectively enrolled. ILD diagnoses were confirmed using High-Resolution Computed Tomography (HRCT) or lung biopsy and characterized by radiologists. GAP scores were calculated for IPF prognosis. 583 serum samples were collected and tested for KL-6, CA-153, CA-199, and CA-125 using specific assays. Statistical analyses compared patients, assessed variables, determined missingness, and predicted ILD, with tools like ROC analysis and logistic regressions. Analyses were performed with IBM SPSS and MedCalc.

ILD patients were older, predominantly male, and had more smokers compared to non-ILD. Both KL-6 and CA-153 were higher in ILD and showed a significant, but non-interchangeable correlation. Age, BMI, smoking, and biomarker levels influenced ILD odds, with KL-6 and CA-153 being the strongest predictors. HRCT imaging highlighted these markers' roles, especially in detecting specific features. Both markers also strongly associated with GAP stages. Stratified analyses emphasized KL-6's significance in predicting ILD across both AD and non-AD groups. Complete data sensitivity analysis reinforced KL-6 and CA-153 as key ILD predictors.

This research emphasizes CA-153 as a feasible, cost-effective alternative to KL-6 in diagnosing and monitoring ILD. Both CA-153 and KL-6 levels were notably elevated in ILD patients, displaying a strong correlation, especially at CA-153 levels of ≤100 U/ml. They both also have significant associations with CT characteristics and GAP stages. The study reinforces the potential of CA-153, particularly in settings where KL-6 testing might be inaccessible or expensive.