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

Haemoglobin (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 70·8% had at least one complication. The most common complications were: painful crises (38·3%), retinopathy (33·8%), cholelithiasis (30·3%), osteonecrosis (24·8%) and sensorineural hearing disorders (9·7%). Frequency of chronic complications was similar in most studies. In multivariate analysis, hearing disorders remained an independent predictor of mortality (Odds Ratio 9·26, 95% confidence interval 1·1-74·8; P = 0·03). 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.