Sickle cell disorders linked to higher risk for COVID-19 hospitalization, death
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Individuals with sickle cell disease or trait demonstrated a higher risk for COVID-19 hospitalization and death than individuals without these conditions, according to study findings published in Annals of Internal Medicine.
“Our group has been exploring the association between ethnicity and COVID-19 outcomes. Sickle cell disorders are predominantly seen in non-white ethnic groups and are known to increase risk for other infections and cause various complications, which may increase COVID-19 risk, such as cardiac and clotting problems,” Ashley Kieran Clift, MA, MBBS, clinical research fellow at University of Oxford in London, told Healio. “The association between sickle cell trait and severe COVID-19 is interesting and was not clear before.
“We therefore felt this was an important aspect to investigate,” Clift added. “Other reports from centers or registries had investigated sickle cell disease, so we sought to analyze this at a larger population level and do so for sickle cell trait.”
Clift and colleagues evaluated data from a population-level database of linked electronic health care records in England that included 12,247,445 children and adults without sickle cell disorders (50.1% male; 61.4% white), 25,682 with sickle cell trait (61.4% female; 53.4% Black) and 5,059 with sickle cell disease (53.8% female; 51.9% Black).
Individuals without sickle cell disorders appeared less likely to test positive for COVID-19 (n = 541,460; 4.42%) than those with sickle cell trait (n = 1,346; 5.24%) and those with sickle cell disease (n = 287; 5.67%).
Researchers used cause-specific Cox regression models stratified by individual general practice to estimate HRs with 95% CIs for COVID-19-associated hospitalizations from Jan. 24 to Sept. 30, 2020, and to Jan. 18, 2021, for death.
Overall, researchers reported 23,699 COVID-19-associated hospitalizations and 19,068 COVID-19-associated deaths. Of these, less than five hospitalizations and no deaths occurred among children with sickle cell disorders, whereas 40 hospitalizations (0.79%) and 10 deaths (0.2%) occurred among adults with sickle cell disease.
Results revealed an association between sickle cell disease and increased risk for COVID-19-associated hospitalization (HR = 4.11; 95% CI, 2.98-5.66) and death (HR = 2.55; 95% CI, 1.36-4.75). The E-value for HR was 7.69 (lower CI limit, 5.41) for COVID-19-associated hospitalization and 4.54 (lower CI limit, 2.06) for COVID-19-associated death, which suggested “robustness to residual confounding,” researchers wrote.
Moreover, among those with sickle cell trait, 98 individuals (0.38%) were hospitalized and 50 (0.19%) died. Sickle cell trait was associated with higher risks for COVID-19-associated hospitalization (HR = 1.38; 95% CI, 1.12-1.7) and death (HR = 1.51; 95% CI, 1.13-2). The E-value for HR was 2.1 (lower CI limit, 1.49) for COVID-19-associated hospitalization and 2.39 (lower CI limit, 1.51) for death.
Researchers acknowledged study limitations, including potential underdiagnosis of sickle cell trait among the study cohort and lack of data on symptoms or presentation.
“These results suggest people with sickle cell conditions may be a higher-risk group, which could be relevant to public health strategies such as vaccination prioritization,” Clift said. “As part of our work funded by the Medical Research Council, we are exploring various factors that may be relevant to understanding the ethnic disparities seen in COVID-19 outcomes.”
For more information:
Ashley Kieran Clift, MA, MBBS, can be reached at University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 4GG, United Kingdom; email: ashley.clift@phc.ox.ac.uk.
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