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A new lymphocyte count in people who come to the hospital with COVID-19 could help doctors identify those at highest risk for admission to the intensive care unit (ICU), new evidence suggests.
Patients with lymphocytopenia were more than three times as likely to require ICU care compared to people with normal lymphocyte counts at admission. Acute kidney injury (AKI) was also more common among people with low absolute lymphocyte counts.
With COVID-19, the severity of the disease can vary widely. “Some patients have minimal or no symptoms, while others develop a serious and debilitating disease that requires ICU admission. Prognostic markers are needed to classify these patients,” co-author Ahmad Farooq, MD, of the Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, University of Texas Health Sciences Center at Houston, and the Division of Gastroenterology and Hepatology, said the Department of Internal Medicine at Duke University, Durham, North Carolina. Medscape Medical News.
Farooq, lead author Jason Wagner, MD, from the Department of Internal Medicine, University of Texas Health Science Center, and colleagues reported the results of their online retrospective cohort study on July 10 in the International Journal of Hematology Laboratory.
“This study shows that the absolute lymphocyte count below 1000 on admission is associated with ICU admission and organ damage, as seen in acute kidney injury,” Farooq said.
Previous research has linked lymphocytopenia to other viral diseases, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Although the mechanism that drives a reduction in lymphocytes in COVID-19 remains unknown, “this is believed to be due to the reduction of peripheral T cells by the sequestration of lymphocytes in specific organs,” Farooq said. Target organs include the lung, the gastrointestinal tract, and lymphoid tissue.
For more information, the researchers evaluated the electronic medical records of 57 adults diagnosed with COVID-19. All participants were admitted to a community academic hospital in Houston between March 1 and May 7, 2020.
A total of 18 people (31%) entered the ICU. Half of this group required intubation and seven of the patients received vasopressors.
The average age of the study population was 58 years, 59% were men and the average body mass index was 32 kg / m.two. Most of the participants (86%) were minorities.
Key results
A higher proportion of patients admitted to the ICU had lymphocytopenia (62%) at the time of hospital admission compared to those who did not enter the ICU (32%). Lymphocytopenia at hospital admission translated into an odds ratio of 3.40 (P = .04).
“Our data suggests that the absolute lymphocyte count may serve as [a] Simple admission test to predict severity of illness, “Farooq said.
The researchers wanted to correlate this finding with the clinical results. They found that participants with lymphocytopenia (68%) were more likely to develop ARI during their hospital stay than patients without lymphocytopenia (33%). AKI was defined as an increase in serum creatine of> 0.3 mg / dL in 48 hours.
Those with low lymphocyte counts were approximately four times more likely to develop ARF (odds ratio, 4.29; P = .01).
“It is evident here that lymphocytopenia may serve as a prognostic marker for AKI in patients with COVID -19,” said Farooq.
Nine of the 57 participants died while in the hospital.
Other possible implications
People with lymphocytopenia on admission were also more likely to need intubation and vasopressors and to have the ICU stay longer than 7 days. There was also a trend toward higher mortality in the lymphocytopenia group. However, these factors did not differ significantly between the groups.
The researchers note that a previous study linked COVID-19 and AKI with higher mortality. “Although lymphocytopenia was not found to be associated with mortality in this study, the finding of association with AKI warrants further investigation.”
The use of an easily obtained laboratory value and the inclusion of a predominantly minority population were the strengths of the study, the researchers say. A small sample size and the performance of the study in a single community hospital were possible limitations.
“We plan to do a prospective study to further validate these findings,” said Farooq. “My laboratory is also studying gastrointestinal involvement in COVID-19 patients.”
Considerable clinical utility?
“This is an interesting study,” said E. John Wherry, PhD, who was not affiliated with the research. Medscape Medical News when asked to comment.
“There is a lot of emerging evidence about lymphopenia in patients with COVID-19. The sickest patients seem to have more severe lymphopenia,” said Wherry.
“The document’s idea that lymphopenia may be prognostic and allow identification of patients on a more severe path of illness could have considerable clinical utility,” said Wherry, director of the Institute of Immunology and Wherry Laboratory at the University of Pennsylvania. in Philadelphia. .
“It will be interesting in the future to determine the cause of this lymphopenia and to question whether lymphopenia contributes to poor control of the infection,” he added.
The results make sense
“This is not a surprising finding, as lymphocytes are essential for maintaining an effective and balanced immune response against SARS-CoV-2,” Brandon Michael Henry, MD, CICU researcher in the Division of Cardiology at the Medical Center of the Cincinnati Children’s Hospital said Medscape Medical News.
Henry added that lymphocyte replacement during the course of the disease may be key to the recovery and survival of COVID-19 patients.
“These results are consistent with the literature to date and provide additional evidence for the inclusion of lymphocyte count in risk stratification models for COVID-19,” said Henry, lead author of a meta-analysis published June 25 that evaluated Hematologic, biochemical, and immune biomarker abnormalities associated with the most severe COVID-19 disease.
The authors, Wherry and Henry have disclosed no relevant financial relationships.
Int J Lab Hematol. Published online July 10, 2020. Full text
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