Serum Krebs von den Lungen-6 level as a prognostic biomarker in patients with interstitial lung abnormalities

Abstract Data associating progression of interstitial lung abnormalities (ILA) and serum biomarkers, including white blood cell differential counts and Krebs von den Lungen-6 (KL-6) are sparse. This study aimed to evaluate the relationship between disease progression and serum biomarkers in patients with ILA. This retrospective cohort study collected data, such as clinical characteristics, pulmonary function test, chest computed tomography (CT), complete blood cell counts, and KL-6 levels from 159 patients (63 with ILA and 74 with interstitial lung diseases [ILDs]) from October 2021 to September 2022. In 42 patients who had previously undergone chest CT, the risk factors for radiologic progression was evaluated using the receiver operating characteristic curve analysis and multivariate logistic regression. Among the 42 patients with ILA, 12 showed radiological progression. Serum KL-6 showed moderate performance with area under the curves ranging from 0.60–0.93 ( p = 0.008) for radiological progression. In multivariate analysis, fibrotic ILA (odds ratio [OR] 6.99; 95% confidence interval [CI], 1.12–43.5) and KL-6 > 400 U/mL (OR, 6.52; 95% CI, 1.14–37.2) were associated with radiological progression. Serum KL-6 level is a reliable indicator of progression of ILA in asymptomatic patients. Patients with serum KL-6 > 400 U/mL require careful observation for radiological progression.