Krebs von den Lungen-6 as a biomarker for distinguishing between interstitial lung disease and interstitial lung abnormalities based on computed tomography findings.

BACKGROUND

Krebs von den Lungen-6 (KL-6), predominantly expressed by type II alveolar cells, is linked to the prognosis and severity of interstitial lung disease (ILD). This investigation sought to explore the relationship between KL-6 concentrations and the presence of ILD versus interstitial lung abnormalities (ILA).

METHODS

This single-center retrospective study included 147 patients who were suspected of ILD and underwent KL-6 testing between October 2022 and March 2023. Epidemiological and clinical details of the patients, including the outcomes of pulmonary function tests and computed tomography findings, were retrospectively extracted from electronic medical records.

RESULTS

The average age within the cohort was 77.1 years, with 97.3% (143 patients) being male. Notably, the ILA group displayed significantly reduced levels of KL-6 compared to the ILD group (411.6±298.8 . 968.8±901.9 U/mL, P<0.001). Utilizing a threshold of 410 U/mL for KL-6, the diagnostic performance yielded an area under the curve (95% CI) of 0.727 (0.605-0.849), demonstrating a sensitivity of 80.8% and a specificity of 64.7%.

CONCLUSIONS

Our findings indicate that serum KL-6 concentrations are markedly elevated in patients with clinically recognized and treated ILD compared to those identified with ILA. Furthermore, the association between higher KL-6 levels and reduced forced vital capacity percentage underlines the biomarker's potential in differentiating between ILD requiring intervention and less severe abnormalities.