Hospitalization and Case Fatality in Individuals with Sickle Cell Disease and COVID-19 Infection

Sickle cell disease (SCD) is an inherited hemoglobinopathy that can affect nearly every organ system. Individuals living with SCD are at high risk of developing serious infections which can further trigger disease related complications and attribute additional morbidity and mortality. In light of the evolving pandemic caused by SARS-CoV-2, the causative agent of COVID-19 disease, and the potential for future infectious disease epidemics, it is important to understand the impact that COVID-19 has on hospitalization rates and mortality in this medically vulnerable population. The objective of this study was to describe hospitalization and case fatality rates secondary to COVID-19 among individuals living with SCD in different age groups and compare these to the general population.

The Medical College of Wisconsin established the international SECURE-SCD Registry to collect data on pediatric and adult COVID-19 infections in individuals living with SCD. Providers are instructed to report confirmed COVID-19 cases to the registry after sufficient time has passed to observe the disease course through resolution of acute illness and/or death. For each case, providers complete a short form that includes the following data: patient demographics, COVID-19 related hospitalization, COVID-19 severity/management strategies, if the patient died due to COVID, and other information about SCD complications. Data are de-identified and without protected health information to facilitate rapid and increased reporting. We calculated the hospitalization rate and case fatality rate for individuals with SCD by specific age group and contrasted it with the rates publicly available for the general Black population. We utilized data from California Department of Public Health for case fatality rate comparison in Blacks and data from COVID-NET for hospitalization rate comparison. We used indirect age adjustment to calculate standardized mortality ratios using COVID-19 data from California state as the reference population.

As of July 17^th 2020, 218 cases of COVID-19 in Blacks with SCD in the US were reported to the registry. There was a slight predominance of females (52.8%) and 32.1% of reported cases were patients 18 years and under. There were 15 deaths reported with overall mortality rate of 6.9%. Figure 1 shows the distribution of cases and deaths by age group and gender. Mortality rate in SCD patients was highest in the 50-64 years age group (23.1%) in contrast to mortality rate peaks seen in the general population in patients older than 80 years (Table 1). Young adult SCD patients aged 18-34 years had a case fatality rate of 3.3% and those aged 34-50 years had a rate of 14.9%. California Department of Public Health report case fatality rates for Blacks are less than 1% in both of these comparative age groups. Age-standardized mortality ratio shows that individuals with SCD are 7.7 times more likely to die due to COVID-19 infection compared to the general population. The overall hospitalization rate in individuals with SCD was 72.5% and 18.8% of reported hospitalized cases were children. Among hospitalized adults with SCD, stratification by age showed that 85% were aged 18-49, whereas only 25.7% of people 18-49 years in the general Black population were hospitalized (Table 2).

Our findings show that individuals with SCD who have COVID-19 infection have higher rates of death due to COVID-19 than the general Black population. Also, a large proportion of COVID hospitalization for the SCD population occurs among the younger age group. Further analysis is planned to examine effects of underlying comorbidities and prior SCD-associated complications on the severity of COVID-19 in individuals with SCD.

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