Vito D’Agnano, Filippo Scialò, Francesco Perna, Lidia Atripaldi, Stefano Sanduzzi, Valentino Allocca, Maria Vitale, Lucio Pastore, Andrea Bianco, Fabio Perrotta, D'Agnano, Vito, Scialò, Filippo, Perna, Francesco, Atripaldi, Lidia, Sanduzzi, Stefano, Allocca, Valentino, Vitale, Maria, Pastore, Lucio, Bianco, Andrea, Perrotta, Fabio, D'Agnano, V., Scialo, F., Perna, F., Atripaldi, L., Sanduzzi, S., Allocca, V., Vitale, M., Pastore, L., Bianco, A., and Perrotta, F.
COVID-19 encompasses a broad spectrum of clinical conditions caused by SARS-CoV-2 infection. More severe cases experience acute respiratory and/or multiorgan failure. KL-6 is a glycoprotein expressed mainly from type II alveolar cells with pro-fibrotic properties. Serum KL-6 concentrations have been found in patients with COVID-19. However, the relevance of KL-6 in patients with severe and critical COVID-19 has not been fully elucidated. Methods: Retrospective data from consecutive severe to critical COVID-19 patients were collected at UOC Clinica Pnuemologica “Vanvitelli”, A.O. dei Colli, Naples, Italy. The study included patients with a positive rhinopharyngeal swab for SARS-CoV-2 RNA with severe or critical COVID-19. Results: Among 87 patients, 24 had poor outcomes. The median KL-6 value in survivors was significantly lower when compared with dead or intubated patients (530 U/mL versus 1069 U/mL p < 0.001). KL-6 was correlated with body mass index (BMI) (r: 0.279, p: 0.009), lung ultrasound score (LUS) (r: 0.429, p < 0.001), Chung Score (r: 0.390, p < 0.001). KL-6 was associated with the risk of death or oro-tracheal intubation (IOT) after adjusting for gender, BMI, Charlson Index, Chung Score, and PaO2/FIO2 (OR 1.003 95% CI 1.001–1.004, p < 0.001). Serum KL-6 value of 968 has a sensitivity of 79.2%, specificity of 87.1%, PPV 70.4%, NPV 91.5%, AUC: O.85 for risk of death or IOT. Conclusions: The presented research highlights the relevance of serum KL-6 in severe to critical COVID-19 patients in predicting the risk of death or IOT.