Sickle Cell Patients at Increased Risk of COVID-19 Hospitalization

Mathias Castonguay, MD

While patients with sickle cell disease (SCD) are at an increased risk of hospitalization with a COVID-19 infection, data presented at 2021 American Society of Hematology (ASH) Annual Meeting & Exposition shows they are not at an increased risk of death.

A team, led by Mathias Castonguay, MD, Department of Medicine, University of Montreal, described the epidemiology, baseline characteristics and clinical outcomes of SCD patients with COVID-19 infection in the province of Quebec and identified the risk factors for hospitalization and severe forms of COVID-19.

Sickle Cell Patients in Quebec

There are approximately 15,000 patients with sickle cell disease living in the province of Quebec, of which are deemed to be immunocompromised and at a higher risk of developing severe COVID-19 infections because of their underlying pro-inflammatory and thrombogenic state, splenic dysfunction, and secondary organopathies.

However, descriptions about disease severity and mortality rates in sickle cell disease vary widely. Investigators from the SECURE-SCD registry found a 0,3% and 4.7% mortality rate in children and adults with sickle cell disease, respectively. Another French registry showed a 2.4% mortality rate among hospitalized patients with COVID-19 and sickle cell disease, which was not different from the generality population.

Ultimately, the COVID-19 morbidity and mortality rates among patients with sickle cell disease is uncertain.

COVID-19 Infections

The investigators built a web-based registry to regroup 7 adult and 4 pediatric tertiary carehospitals in Quebec in June 2020. All patients with sickle cell disease also had a SARS-CoV-2 infection confirmed by a PCR test.

The team compared the prevalence of infection and hospitalization rates of patients with sickle cell disease to the general population of Quebec using epidemiological data found in the National Institute of Public Health of Quebec (INSPQ) public database.

The investigators analyzed data from March 1, 2002 to March 1, 2021 and calculated relative risk using bilateral association measures, including exact fisher, mid-p, or chi-square to compare the incidence of infection and hospitalization of patients with sickle cell disease to the general population.

There were 74 patients included in the registry during the 12 month time period, with the male to female ratio of 1:1.12 and the median age was 23 years. The investigators identified SS-Sbeta⁰ genotypes present in 51% of cases, 49% of which were SC or Sbeta⁺. Most patients were on diseases modifying therapy, with 54% on hydroxyurea and 17.5% on exchange transfusion therapy.

The COVID-19 infection incidence rate was significantly higher in patients with sickle cell disease compared to the general population (4.9% vs. 3.5%; P = 0.002).

The patients with SCD also had a rate of hospitalization 10-times greater than the general population (33.8% vs. 3.2%; P <0.001). However, the risk of ICU admission was similar between the 2 groups (24.0% vs. 24.1%, P = 0.99) and no deaths were recorded amongst SCD patients with COVID-19 compared to a death rate in the general population in Quebec of less than 70 years old of 48-78 for 100,000 infections.

However, some cardiovascular problems, including a history of acute chest syndrome in the previous year (OR, 2.6; 95% CI, 1.5-4.6; P = 0.04) and arterial hypertension (OR, 3.3; 95% CI, 2.3-4.8; P = 0.01) were linked to a higher risk of hospitalization.

There was no statistically significant association with age, sex, genotype, ABO blood group, baseline SCD therapy, or other comorbidities, including chronic renal disease, obesity, pulmonary hypertension, chronic lung disease and previous admission to ICU in the cohort.

“Similar to other reports, we found that SCD patients were at much greater risk of hospitalization compared to the general population,” the authors wrote. “We however found no increased risk of mortality or disease complication.”

However, the investigators suggest more research and a steady stream of data monitoring in the future.

“Whether social determinants of health could explain some of the outcome variability between different countries merit further investigation,” the authors wrote. “Furthermore, we believe that registries are critical to monitor the impact of preventive measures.”

The study, “COVID-19 and Sickle Cell Disease in the Province of Quebec: Morbidity and Mortality Rates Derived from the Provincial Registry,” was published online by ASH.