Prognostic roles of KL‐6 in disease severity and lung injury in COVID‐19 patients: A longitudinal retrospective analysis

Abstract

To investigate the dynamic changes of Krebs von den Lungen‐6 (KL‐6) among patients with coronavirus disease 2019 (COVID‐19) and the role of KL‐6 as a noninvasive biomarker for predicting long‐term lung injury, the clinical information and laboratory tests of 166 COVID‐19 patients were collected, and a correlation analysis between KL‐6 and other parameters was conducted. There were 17 (10.2%, 17/166) severe/critical and 149 (89.8%, 149/166) mild COVID‐19 patients in our cohort. Serum KL‐6 was significantly higher in severe/critical COVID‐19 patients than in mild patients (median 898.0 vs. 451.2 U/ml, p < .001). KL‐6 was next confirmed to be a sensitive and specific biomarker for distinguishing mild and severe/critical patients and correlate to computed tomography lung lesions areas. Serum KL‐6 concentration during the follow‐up period (>100 days postonset) was well correlated to those concentrations within 10 days postonset (Pearson r = .867, p < .001), indicating the prognostic value of KL‐6 levels in predicting lung injury after discharge. Finally, elevated KL‐6 was found to be significantly correlated to coagulation disorders, and T cells subsets dysfunctions. In summary, serum KL‐6 is a biomarker for assessing COVID‐19 severity and predicting the prognosis of lung injury of discharged patients.

sFlt-1 and CA 15.3 are indicators of endothelial damage and pulmonary fibrosis in SARS-CoV-2 infection

“…Similarly, Deng et al 45 described KL-6 as sensitive and specific biomarker for distinguishing mild and severe/critical patients correlated to computed tomography lung lesions areas and predicting the prognosis of lung injury of discharged patients.…”

The Potential of Lung Epithelium Specific Proteins as Biomarkers for COVID-19-Associated Lung Injury

“…KL-6 levels were significantly decreased after months of recovery in comparison to KL-6 levels that were obtained at the admission, suggesting that interstitial lung abnormalities related to SARS-CoV-2 infection were not progressive in the majority of patients [30]. Similarly, a recent study reported that KL-6 levels gradually reduced after reaching a peak in 1 month [31].…”

Association of serum KL-6 levels on COVID-19 severity: A cross-sectional study design with purposive sampling

“…Changes were found in the severe group, while the non-severe group tended to be stable [ 11 ]. Deng et al said that serum KL-6 value has increased and reaches a peak for up to 1 month, then has a gradual decrease until the 6th month [ 12 ]. Awano et al said that serum KL-6 experienced an increase on day 6 in the severe group, while the non-severe group tended to be stable [ 10 ].…”

“…Awano et al Deng et al, Xue et al and Alessandro et al said that serum KL-6 value in the severe group was higher than that in the non-severe group. Deng et al Xue et al and Alessandro et al said that serum KL-6 normal patients have the same as the non-severe group [ [9] , [10] , [11] , [12] ]. This study and the previous study show different results.…”

“…Serum KL-6 value of the severe group of COVID-19 was higher than the non-severe group. The study also stated that serum KL-6 undergoes dynamic changes with the patient's clinical condition so that it can be used as a biomarker of severity [ [10] , [11] , [12] ]. Other several studies have shown less significant results.…”