Characteristics and Predictive Factors of Chronic Complications in a Cohort of Hemoglobin Sc Disease Patients from Dakar, Senegal

Hemoglobin SC disease is characterized by less severe morbidity than in homozygous form. Nevertheless vaso-occlusive crisis was reported to be less frequent, some chronic complications are more frequent, such as retinopathy and osteonecrosis of femoral head. This study aimed to describe the chronic complications of Hb SC disease patients and to identify associated predictive factors. This cohort included 132 Hb SC patients followed between 1995 and 2015 with a mean of 6.2 patients/year. Patients were monitored with at least two medical visits per year. Screening for chronic complications was performed every two years by biological and radiological analyzes. Bivariate analysis was carried out to evaluate the predictive factors of chronic complications. Medium age was 42 years (4-73). Median number of follow-up was 14 years (3-21). Sex ratio (M/F) was 0.85. Circumstances of discovery were bone pain (73.5%), fortuitous discovery (12.9%) or chronic complications (5.3%). Mean number of vaso-occlusive crisis/year was 1 (0 5). Twenty seven patients (19.4%) had chronic complications including osteonecrosis of femoral head (11.3%), retinopathy (9.8%) and chronic osteomyelitis (3%). Risks factors identified were age (p = 0.0006), irregular follow-up (p = 0.007) and high white blood cell count (p = 0.002). This study confirms that Hb SC disease is associated with a recrudescence of chronic complications. Osteonecrosis of the femoral head and retinopathy are more frequently described. Two predictive factors of these chronic complications that are rarely described have been identified in our patients: irregular follow-up and high number of white blood cells count.