Cohort study of adult patients with haemoglobin SC disease: clinical characteristics and predictors of mortality

Abstract

SummaryHaemoglobin (Hb) SC disease is the second most common subtype of sickle cell disease and is potentially fatal. This study aimed to determine the clinical characteristics, outcome and predictors of mortality in HbSC disease patients, and to compare these findings with patients followed-up in different centres. Clinical, laboratory and outcome data were collected from a cohort of adult patients with HbSC disease followed between 1991 and 2103. Cox regression multivariate analysis was used to determine predictors of mortality. One hundred and fifty-five patients were followed-up over 20 years: 9% died and 70Á8% had at least one complication. The most common complications were: painful crises (38Á3%), retinopathy (33Á8%), cholelithiasis (30Á3%), osteonecrosis (24Á8%) and sensorineural hearing disorders (9Á7%). Frequency of chronic complications was similar in most studies. In multivariate analysis, hearing disorders remained an independent predictor of mortality (Odds Ratio 9Á26, 95% confidence interval 1Á1-74Á8; P = 0Á03). It was concluded that patients with HbSC disease receive a late diagnosis and there is remarkable similarity between the studies conducted in different centres around the world. Sensorineural hearing disorders were an independent predictor of mortality, suggesting that it may be useful to implement routine diagnostic screening.

A proposed treatment algorithm for adults with Haemoglobin SC disease

“…Two patients died, both from sepsis. Within this large North American cohort of adult HbSC patients, the findings are consistent with previous conclusions that VOC, retinopathy and osteonecrosis are among the most prevalent complications found in this population (Koduri et al, 2001;Gualandro et al, 2015). Hence, treatment and prevention of end-organ damage is warranted.…”

“…Baseline characteristics were similar to those presented by two other groups, of French (Lionnet et al, 2012) and Brazilian cohorts (Gualandro et al, 2015). Indeed, median haemoglobin was 119 g/l, haematocrit was 34% and mean haemoglobin F (HbF) level was 1Á15%.…”

“…Leg ulcers were rare, affecting 1% of patients. Sensorineural deficit, frequently observed by Lionnet et al (2012) and Gualandro et al (2015), was not part of our routine screening (Table I).…”

Risk factors for venous thromboembolism in adults with hemoglobin SC or Sβ+ thalassemia genotypes

“…(4) In light of these observations, several clinical groups routinely perform therapeutic phlebotomy for patients with sickle cell variant syndromes who experience clinical complications. (8,13,14) The role of viscosity in the pathophysiology of VTE and role of phlebotomy for treatment or prophylaxis for VTE in patients with SC or Sβ + thalassemia, however, requires more formal investigation.…”

“…High baseline hemoglobin is associated with viscosity-related sequelae such as proliferative retinopathy and multi-organ failure in SC disease;(7–9) whereas hemoglobin levels do not appear to be associated with other common complications such as sensorineural hearing loss in SC patients. (8) To date, however, the risk factors for VTE in patients with sickle cell disease variants have not been investigated.…”