Decreased eosinophil counts and elevated lactate dehydrogenase predict severe COVID-19 in patients with underlying chronic airway diseases

Abstract

Background: Several predictors of COVID-19 severity have been reported. However, chronic airway inflammation characterised by accumulated lymphocytes or eosinophils may affect the pathogenesis of COVID-19.

Methods: In this retrospective cohort study, we reviewed the medical records of all patients with laboratory-confirmed COVID-19 with chronic bronchitis, chronic obstructive pulmonary disease (COPD) and asthma admitted to the Sino-French New City Branch of Tongji Hospital, a large regional hospital in Wuhan, China, from 26 January to 3 April. The Tongji Hospital Ethics Committee approved this study.

Results: There were 59 patients with chronic bronchitis, COPD and asthma. When compared with non-severe patients, severe patients were more likely to have decreased lymphocyte counts (0.6×10⁹/L vs 1.1×10⁹/L, p<0.001), eosinopaenia (<0.02×10⁹/L; 73% vs 24%, p<0.001), increased lactate dehydrogenase (LDH) (471.0 U/L vs 230.0 U/L, p<0.001) and elevated interleukin 6 level (47.4 pg/mL vs 5.7 pg/mL, p=0.002) on admission. Eosinopaenia and elevated LDH were significantly associated with disease severity in both univariate and multivariate regression models including the above variables. Moreover, eosinophil count and LDH level tended to return to normal range over time in both groups after treatment and severe patients recovered slower than non-severe patients, especially in eosinophil count.

Conclusions: Eosinopaenia and elevated LDH are potential predictors of disease severity in patients with COVID-19 with underlying chronic airway diseases. In addition, they could indicate disease progression and treatment effectiveness.

Keywords: COVID-19.

Figure 1

Clinical characteristics of eosinophil and LDH in patients with COVID-19 with chronic airway inflammation. (A) Eosinophil counts in different subgroups. Eosinophil counts were significantly decreased in patients with severe COVID-19 with chronic bronchitis and COPD. (B) LDH levels in different subgroups. LDH levels were significantly decreased in patients with severe COVID-19 with chronic bronchitis and COPD. Values for non-severe and severe patients are presented with open and closed circles, respectively. Mann-Whitney U test was used. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. COPD, chronic obstructive pulmonary disease; LDH, lactate dehydrogenase.

Figure 2

Dynamic changes of eosinophil counts and LDH levels in patients with COVID-19 with chronic airway diseases. (A–D) Eosinophil counts increased over time in non-severe and severe patients with COVID-19 with chronic bronchitis (n=31), COPD (n=18) and asthma (n=10). (E–H) LDH levels decreased over time in non-severe and severe patients with COVID-19 with chronic bronchitis (n=31), COPD (n=18) and asthma (n=10). Values for non-severe and severe patients are presented with open and closed circles, respectively. Mann-Whitney U test was used. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001, compared with the eosinophil counts or LDH levels between severe and non-severe patients. COPD, chronic obstructive pulmonary disease; LDH, lactate dehydrogenase.