Are Elevated Plasma D-Dimer Levels a Reliable Marker of Disease Severity of Vaso-Occlusive Crisis in Sickle Cell Anaemia?

Background: Sickle Cell Anaemia (SCA) is characterized by a hypercoagulable state due to complex activation of haemostatic pathways involving red cell membrane changes, endothelial injury and cellular activation. Vaso-occlusive crisis (VOC), the most common acute complication in SCA, results from microvascular obstruction leading to tissue hypoxia and pain. This study determined plasma D-dimer levels during Bone Pain Crises (BPC), the steady state, and evaluated its utility as a marker of disease severity in SCA patients. Materials and Methods: Forty-five adult SCA patients were recruited from a Nigerian teaching hospital during bone pain crises (BPC) and reassessed four weeks post-therapy in steady state. Clinical and laboratory parameters, including pain scores, haematological indices, and D-dimer levels were measured. Severity scores were calculated based on clinical complications and laboratory values. Results: The study findings demonstrated significantly elevated median D-dimer levels during BPC (3.2 µg/ml) compared to the steady state (1.8 µg/ml, p = 0.004), consistent with increased fibrinolytic activity during acute crises. Haematocrit decreased (p = 0.002), white cell counts increased (p < 0.0001), and platelet counts decreased (p = 0.005) during VOC, reflecting an acute inflammation response. Males exhibited higher D-dimer levels than females during VOC (6.3 vs. 3.6 µg/ml, p = 0.002). Weak correlations were observed between D-dimer levels and disease severity indices, with no significant correlation overall (ρ = 0.217, p = 0.152). Conclusion: This study confirms that BPC in SCA is associated with a hypercoagulable state and increased fibrinolytic activity, as evidenced by elevated D-dimer levels. However, D-dimer may not reliably reflect disease severity during BPC. The findings support the potential role of D-dimer as a biomarker of coagulation activation during VOC and underscore the importance of considering anticoagulant therapies in managing acute SCA complications.