Epidemiological, clinical, and severity characterization of sickle cell disease in a population from the Brazilian Amazon

Abstract

Objective/background: Sickle cell disease (SCD) is a chronic inflammatory condition caused by a point mutation in the HBB gene. Here we characterized the clinical presentation of SCD in a population from Amazonas State in northern Brazil, in order to evaluate whether the higher Amerindian ancestry observed in this relatively isolated geographic region would influence the clinical presentation of SCD.

Methods: This was a cross-sectional study characterizing the clinical presentation of SCD patients registered at HEMOAM, Amazon, Brazil. Data were obtained using a structured questionnaire, and by a review of the medical records.

Results: Of the 236 SCD patients listed in the historical records, 122 were included in this study. The median age was 15 years, with a male to female ratio of 52:70. The population was characterized by a high level of socioeconomic vulnerability, with only 2.1% presenting a family income above five minimum wages. Homozygous HbS (SS) was the most prevalent form of SCD (89.7%), and the diagnosis of SCD was performed in the context of complications in 92.3% of patients. The median frequency of vaso-occlusive crisis in the past 12 months was 2 (0-10). Using a validated clinical severity score based on clinical and laboratory data, no significant difference could be observed when compared to other populations.

Conclusion: Our results represent the first comprehensive characterization of epidemiological, laboratorial, and clinical data of SCD in the region of the Brazilian Amazon. Despite the higher contribution of Amerindian ancestry previously demonstrated in this region, the main clinical characteristics of SCD seem similar to those reported in other populations.

Keywords: Epidemiology; Severity score; Sickle cell disease; Socioeconomic characterization.