DREPA-COG is an observational study evaluating the effect of exchange transfusions on cognitive function in adults with severe sickle cell disease (SS or Sβ0). Information processing speed is assessed at three time points during the transfusion cycle using the Symbol Digit Modalities Test (SDMT) and additional validated neuropsychological measures. This minimal-risk, fully remote study aims to identify processing speed as a reproducible marker for clinical monitoring and future therapeutic trials.

DREPA-COG is a non-interventional, multicenter observational study investigating the effect of exchange transfusions on cognitive performance in adults with severe sickle cell disease (SS or Sβ0). Cognitive complications, including slowed information processing and executive dysfunction, are frequent and disabling in this population. Exchange transfusion, a standard therapy replacing sickled red blood cells with donor cells, may positively influence cognition, but systematic evidence is lacking. The study evaluates information processing speed as a potential neurological marker across the transfusion cycle. Participants complete three brief neuropsychological assessments remotely by videoconference: before the transfusion, one week after, and prior to the next transfusion. The Symbol Digit Modalities Test (SDMT) is the primary measure, complemented by validated assessments of global cognition, attention, memory, fatigue, mood, and pain. Primary analysis will use mixed-effects models to assess changes in processing speed over time, adjusting for demographic and clinical covariates. This minimal-risk, fully remote study requires no additional hospital visits and aims to establish processing speed as a reproducible and clinically relevant outcome measure in sickle cell disease.