Is There a Difference in Occurrence of Complications Between Adults With Hemoglobin SS and Hemoglobin SC Disease: An Extended Systematic Review.

Sickle cell disease (SCD) is characterized by both acute and chronic complications. The clinical manifestation of these complications differs between genotypes. Given the large amount of research already published, this systematic review aims to offer a complete overview of types of sickle cell complications between adults in the most common genotypes Hemoglobin SS (HbSS) and Hemoglobin SC (HbSC), putting options for further research into perspective. An extensive literature search was performed to study all available evidence on these complications. This review was performed according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) statement guidelines, and was performed on January 2, 2024. A total of 710 references were identified. After careful screening, 521 records were excluded based on title and abstract and other exclusion criteria. In total, 158 articles were excluded after full-text assessment. Our analysis of 31 studies highlights key differences in complications between HbSS and HbSC genotypes in sickle cell disease (SCD). Vaso-occlusive crises (VOCs) remain the most common acute complication in both genotypes. HbSS patients experience more frequent VOCs, while HbSC patients generally have a milder clinical course when it comes to acute complications. Chronic complications, particularly in the ocular and pulmonary systems, are more prevalent in HbSC patients. However, as acute complications are more common in HbSS and chronic complications more common in HbSC, both genotypes face progressive organ damage due to recurrent ischemic injury and inflammation.