Hematologic parameters in patients with COVID-19 infection

Fan, B. E., Chong, V. C. L., Chan, S. S. W., Lim, G. H., Lim, K. G. E., Tan, G. B., ... & Ong, K. H. (2020). Hematologic parameters in patients with COVID-19 infection. American journal of hematology.

Review written by:

Robert Parry, edited by Lillian Zerihun

Yellow - Unique investigation across course and severity; limited by sample size and non-standardization

The authors present a retrospective study of the hematologic parameters of 69 confirmed cases of COVID-19 treated at the National Centre for Infectious Diseases in Singapore between January 23 and February 28.

Admission Parameters: There were different hematologic parameters at admission for the ICU group (n = 9) compared to the non-ICU group (n = 58). The differences are represented in the median of the ICU group and the non-ICU group, respectively, for:

  • admission LDH:     1684 vs. 401 U/mL (p = 0.003)

  • admission Absolute Lymphocyte Count: 0.5 vs. 1.3 x 109/L (p < 0.001)

Parameters Across Clinical Course: There were also differences of the hematologic parameters over the patients’ clinical courses. The differences are represented in the median of the ICU group and the non-ICU group, respectively, for:

  • peak Absolute Neutrophil Count:  11.6 vs. 3.5 x 109/L (p < 0.001)

  • peak LDH:    1081 vs. 451 U/L (p < 0.001)

  • nadir hemoglobin:   11.1 vs. 13.6 g/dL (p < 0.001)

  • nadir Absolute Lymphocyte Count:  0.4 vs. 1.2 x 109/L (p < 0.001)

  • nadir Absolute Monocyte Count:  0.2 vs. 0.4 x 109/L (p<0.001)

Other Parameters in ICU vs Non-ICU Patients: In addition, the ICU group had significantly lower CD45+, CD3+, CD4+, CD8+, CD19+, CD15/56+ lymphocyte counts compared to non-ICU patients on flow cytometry (actual values not discussed).

Parameters in Previous Outbreaks: Finally, some hematologic parameters differed from previous viral outbreaks. Amongst the lymphopenic patients in this study, 69% had the presence of reactive lymphocytes, which were not observed in the SARS outbreak of 2003. Also, no patient presented with moderate or severe thrombocytopenia that is frequently associated with other viral illnesses such as dengue fever.

Review Notes
 
  • The ICU group was relatively small (n=9), and had a median age of 54 vs the median age of 42 for the non-ICU group.

  • Some tests (e.g. LDH and flow cytometry) were not conducted in all patients.

  • Hematologic parameters were not correlated with onset of symptoms; admission may have occurred at different points in the clinical course depending when the patient presented for care.

  • The treatment the patients received was not discussed and may not have been standardized. The treatment would affect the hematologic parameters over the patients’ clinical course.

  • 28% of all the study’s patients presented with lymphopenia, which is significantly smaller than cohorts of patients in China. This may reflect the extent of epidemiologic data in the surveillance pyramid there.

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