European Journal of Medical Research (May 2022)

Peak value of serum KL-6 may be useful for predicting poor prognosis of severe COVID-19 patients

  • Shuhei Maruyama,
  • Yasushi Nakamori,
  • Hitoshi Nakano,
  • Keiko Tsuyumu,
  • Shuji Kanayama,
  • Hiromu Iwamura,
  • Daiki Wada,
  • Tomoyuki Yoshihara,
  • Fukuki Saito,
  • Kazuhisa Yoshiya,
  • Yasuyuki Kuwagata

DOI
https://doi.org/10.1186/s40001-022-00690-3
Journal volume & issue
Vol. 27, no. 1
pp. 1 – 10

Abstract

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Abstract Background Serum Krebs von den Lungen 6 (KL-6), which reflects alveolar epithelial injury, was reported to be useful to predict the progression of pneumonitis induced by COVID-19 in the early phase. This study aimed to evaluate the peak value of serum KL-6 during hospitalization for COVID-19 to discover a more useful biomarker for predicting prognosis in COVID-19 patients. Methods In this retrospective, single-center, observational study, we analyzed the data of 147 hospitalized patients who required supplemental oxygen, high-flow oxygen therapy, or invasive mechanical ventilation for respiratory failure due to COVID-19 from March 2020 to February 2021. We extracted data on patient sex, age, comorbidities, treatment, and biomarkers including the initial and peak values of KL-6. Inclusion criteria were examination of the studied biomarkers at least once within 3 days of admission, then at least once a week, and at a minimum, at least twice during the entire hospitalization. Area under the receiver operating curve (AUC) was analyzed to determine the accuracy of several biomarkers including KL-6 and LDH for predicting poor prognosis defined as survivors requiring invasive mechanical ventilation for over 28 days or non-survivors of COVID-19. Univariable and multivariate logistic regression analyses were performed to investigate the prognostic value of the baseline characteristics and biomarkers. Results Among the 147 patients, 108 (73.5%) had a good prognosis and 39 (26.5%) had a poor prognosis. The AUC analysis indicated that peak KL-6 showed precise accuracy in the discrimination of patients with poor prognosis (AUC 0.89, p < 0.001). The best cut-off value for KL-6 concentration was 966 U/mL (sensitivity 81.6%, specificity84.3%). After adjustment, increasing peak values of KL-6 or LDH were associated with a high risk of poor prognosis, with an adjusted odds ratio of 1.35 for peak value of KL-6, per 100 U/mL increase (95% CI 1.17–1.57, p < 0.001) and 2.16 for peak value of LDH, per 100 U/L increase (95% CI 1.46–3.20, p < 0.001). Conclusions Peak values of KL-6 and LDH measured during hospitalization might help to identify COVID-19 patients with respiratory failure who are at higher risk for a poor prognosis.

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