Development of a Clinical Severity Score for Indian Sickle Cell Anaemia Patients

Sickle cell anaemia (SCA) is a monogenic disorder but shows variable disease severity. We evaluated the utility of paediatric severity scores (PSS) in Indian patients and developed two modified scores: Indian Severity Score 1 (ISS1) by adding four clinical parameters to PSS, and ISS2 by excluding four biochemical measures from ISS1.

Clinical details of 171 SCA patients were collected from hospital records and categorized into mild, moderate, and severe groups by two clinical experts. Same patients were randomly assigned to three training sets-R1, R2 and R3 (N = 86 each) and severity cut-off values for PSS, ISS1 and ISS2 were defined to assign them into mild, moderate, and severe categories. The scores were tested on the remaining three random testing set patients, R1, R2 and R3 (N = 85 each), and overall concordance with clinical expert categorization was assessed.

The concordance of PSS was 66.7%, while ISS1 and ISS2 were 82.8% and 85.1%, respectively. In all three severity scoring models, the highest concordance was observed in mild (81%-100%) followed by severe (57%-85%), and the lowest in the moderate groups (10%-48%).

Overall, we have developed a robust, population-specific severity score for Indian SCA patients, highlighting the importance of including population-specific clinical features. Trial Registration: The authors have confirmed clinical trial registration is not needed for this submission.