analysis(1) database(1) Patient(1) Admission(1) Serum ferritin(1) Joanna Briggs Institute(1) Cell(1) Meta-analysis(1) conducted(1) ferritin(1) Case series(1) critical appraisal(1) Sickle cell disease.(1) 95% CI(1) serum ferritin level(1) proportion(1) systematic review(1) Sickle(1) ICU(1) ICU admission(1) predict(1) Web of Science(1) article(1) SCD(1) review(1) determine(1) outcome(1) COVID-19 infection(1) disease(1) Severe COVID-19 Infection(1)