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  1. D. Lobo Prat1,
  2. I. Castellví1,
  3. D. Castillo2,
  4. S. Orozco2,
  5. A. Mariscal3,
  6. L. Martínez-Martínez3,
  7. A. M. Millán Arciniegas1,
  8. P. Moya1,
  9. A. Laiz1,
  10. C. Díaz-Torné1,
  11. B. Magallares1,
  12. S. P. Fernandez-Sanchez1,
  13. S. Jeria Navarro1,
  14. L. Sainz Comas1,
  15. H. Codes1,
  16. J. Casademont4,
  17. P. Domingo5,
  18. H. Corominas1
  1. 1Hospital de la Santa Creu i Sant Pau, Rheumatology, Barcelona, Spain
  2. 2Hospital de la Santa Creu i Sant Pau, Pneumology, Barcelona, Spain
  3. 3Hospital de la Santa Creu i Sant Pau, Immunology, Barcelona, Spain
  4. 4Hospital de la Santa Creu i Sant Pau, Internal Medicine, Barcelona, Spain
  5. 5Hospital de la Santa Creu i Sant Pau, Infectious Diseases, Barcelona, Spain


Background: Currently, there are no biomarkers to predict respiratory worsening in patients with Coronavirus infectious disease, 2019 (COVID- 19) pneumonia.

Objectives: We aimed to determine the prognostic value of Krebs von de Lungen-6 circulating serum levels (sKL-6) predicting COVID- 19 evolving trends.

Methods: We prospectively analyzed the clinical and laboratory characteristics of 375 COVID- 19 patients with mild lung disease on admission. sKL-6 was obtained in all patients at baseline and compared among patients with respiratory worsening.

Results: 45.1% of patients developed respiratory worsening during hospitalization. Baseline sKL-6 levels were higher in patients who had respiratory worsening (median [IQR] 303 [209-449] vs. 285.5 [15.8-5724], P=0.068). The best sKL-6 cut-off point was 408 U/mL (area under the curve 0.55; 33% sensitivity, 79% specificity). Independent predictors of respiratory worsening were sKL-6 serum levels, age >51 years, time hospitalized, and dyspnea on admission. Patients with baseline sKL-6 ≥ 408 U/mL had a 39% higher risk of developing respiratory aggravation seven days after admission. In patients with serial determinations, sKL-6 was also higher in those who subsequently worsened (median [IQR] 330 [219-460] vs 290.5 [193-396]; p<0.02).

Conclusion: sKL-6 has a low sensibility to predict respiratory worsening in patients with mild COVID-19 pneumonia. Baseline sKL-6 ≥ 408 U/mL is associated to a higher risk of respiratory worsening. sKL-6 levels are not useful as a screening tool to stratify patients on admission but further research is needed to investigate if serial determinations of sKL-6 may be of prognostic use.

References: [1]Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020;395(10229):1054-62. 5.

[2]Tian W, Jiang W, Yao J, Nicholson CJ, Li RH, Sigurslid HH, et al. Predictors of mortality in hospitalized COVID-19 patients: A systematic review and meta-analysis. J Med Virol. 2020.

[3]Wang D, Li R, Wang J, Jiang Q, Gao C, Yang J, et al. Correlation analysis between disease severity and clinical and biochemical characteristics of 143 cases of COVID-19 in Wuhan, China: a descriptive study. BMC Infect Dis. 2020;20(1):519.

Disclosure of Interests: None declared.

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