Risk factors for Venous Thromboembolism and clinical outcomes in adults with sickle cell disease

Hypercoagulability in hemoglobinopathies: Decoding the thrombotic threat

Beta (β)-thalassemia and sickle cell disease (SCD) are characterized by a hypercoagulable state, which can significantly influence organ complication and disease severity. While red blood cells (RBCs) and erythroblasts continue to play a central role in the pathogenesis of thrombosis in β-thalassemia and SCD, additional factors such as free heme, inflammatory vasculopathy, splenectomy, among other factors further contribute to the complexity of thrombotic risk. Thus, understanding the role of the numerous factors driving this hypercoagulable state will enable healthcare practitioners to enhance preventive and treatment strategies and develop novel therapies for the future. We herein describe the pathogenesis of thrombosis in patients with β-thalassemia and SCD. We also identify common mechanisms underlying the procoagulant profile of hemoglobinopathies translating into thrombotic events. Finally, we review the currently available prevention and clinical management of thrombosis in these patient populations.

Hospital acquired venous thromboembolism in children with sickle cell disease

Sickle cell disease (SCD) is well recognized as a hypercoagulablestate, however, it remains unclear whether a subgroup of children with SCD at higher risk of venous thromboembolic event (VTE) during hospitalization may benefit from thromboprophylaxis. Our objectives were to describe the clinical characteristics, outcomes and recurrence of hospital acquired VTE in patients with SCD younger than 21 years. This was a single center retrospective study. Data regarding demographics, reason for admission, location of VTE, risk factors like central venous catheter (CVC), intensive care unit (ICU) admission among others were extracted from electronic medical records over a 10-year study period (2011-2021). Recurrence of VTE at 1 and 5 years was assessed. Descriptive statistics were used as indicated. We identified a total of 20 VTE events over the 10-year study period. Six of these events occurred in those younger than 12 years of age. Fourteen (70%) VTE events occurred in the HbSS or HbSβThal0 genotypes compared to 6 (30%) in HbSC. Most common VTE was isolated pulmonary embolism (PE) (n = 10, 50%). VTE were most often associated with acute chest syndrome (ACS) (n = 14, 70%), ICU admissions (n = 10, 50%) and CVC (n = 5/9, 55%). One patient died from the VTE event. One patient with additional underlying risk factors had a recurrent VTE at 13 months. Our study suggests that ICU admission, ACS and presence of CVC increases the risk of VTE in children and young adults with SCD, but larger studies are indicated to validate our findings.

Predisposing Factors and Incidence of Venous Thromboembolism among Hospitalized Patients with Sickle Cell Disease

Though patients with sickle cell disease (SCD) are at risk of developing venous thromboembolism (VTE), clear estimates of its incidence and predisposing factors in hospitalized SCD patients are not available. Therefore, this issue was addressed to facilitate an early diagnosis and initiate appropriate prophylactic and treatment strategies. A retrospective observational study was conducted on patients with SCD who were admitted to an academic center in Saudi Arabia over a 10-year period. We identified 1054 admissions of 394 patients with SCD. Of the 3% of patients identified with VTE, 50% experienced pulmonary embolism (PE), 34.3% exhibited deep vein thrombosis (DVT), 6.3% exhibited cerebral vein thrombosis, and 9.4% showed other forms of VTE. In pregnant SCD patients, 6.4% developed a VTE event during their hospital admission. Of the risk factors, high white blood cell count, length of stay, and presence of any additional risk factor for VTE was associated significantly with higher risk of VTE. In our study, this risk seems to be much lower, which is likely attributed to the use of VTE prophylactic strategies implemented in our center. Nevertheless, further studies are needed to establish the ideal prophylactic strategy in patients with SCD.

[Splenic dysfunction in sickle cell disease: An update]

The spleen filters blood cells and contributes to the immune defense. The red pulp clears the blood from altered red blood cells via its unique microcirculatory network ; while the white pulp is a secondary lymphoid organ, directly connected to the bloodstream, whose specificity is the defense against encapsulated bacteria through the production of "natural" IgM in the marginal zone. Various health conditions can cause acquired impairment of the splenic function (or hyposplenism) directly and/or through therapeutic splenectomy. Hypo/asplenia is complicated by an increased susceptibility to encapsulated germ infections, but an increased risk of thrombosis and pulmonary hypertension has also been reported after surgical splenectomy. Homozygous sickle cell disease is the most common disease associated with functional asplenia. The latter appears early in childhood likely through repeated ischemic alterations caused by the sickling of red blood cells. In addition, specific complications such as hypersplenism and acute splenic sequestration can occur and may be life-threatening. We provide here an update on the role and physiology of the spleen, which will allow a better understanding of the pathophysiology of spleen damage and its consequences in sickle cell disease.

Deep Vein Thrombosis of the Left Lower Limb in a Sudanese Child with Sickle Cell Disease

This is a case of an eleven-year-old female Sudanese child, a known Sickle Cell Anemia (SCA) patient, who presented with fever, as well as left thigh and leg swelling that was associated with pain and warmness, which was diagnosed as Deep Vein Thrombosis (DVT) of her left lower limb. She had a previous history of admissions to the emergency room, during which she once received blood. The patient was managed by carrying out a basic routine initial laboratory investigation. A Doppler ultrasound scan showed features consistent with DVT. Based on the clinical findings and investigation results, management began by providing the patient with intravenous fluid, analgesia, packed Red Blood Cells (RBCs), intravenous antibiotics, and low-molecular-weight heparin. Further consultations showed that there was no need for vascular surgery or surgical intervention. This case highlights the need for more studies on DVT and Venous Thromboembolism (VTE) complications in children with SCA, so as to develop strategies for diagnosis and management in order to reduce the risk of life-threatening complications of VTE in patients with Sickle Cell Disease SCD.

Prevalence of venous thromboembolism and its associations in a large racially homogenous population of sickle cell disease patients

To determine the prevalence of venous thromboembolism (VTE) among adult sickle cell disease (SCD) patients in Nigeria.

METHODS

This was a multicentre retrospective study in which the medical records of adult SCD patients were reviewed. Information on demographics, steady-state haemogram, clinical phenotypes, duration of follow-up, history of VTE including risk factors and management was collected.

RESULTS

Of the 509 SCD patients with a median (IQR) duration of follow-up of 2 years, 10 (2.0%) had VTE (9 DVT and 1 PE). Their median (IQR) age was 27 (22.8-30.3) years. Identifiable risk factors for VTE included positive family history (2, 20%) surgery, splenectomy, paraplegia and cancer (1, 10% each). No risk factor was identifiable in four persons. VTE had no significant association with age and gender. VTE was significantly associated with the following events: acute chest syndrome [p = .002, odds ratio (OR) 8, 95% CI 2.2-28.9], osteonecrosis [p = .012, OR 5.24, 95% CI, 1.45-18.91] and vaso-occlusive crisis [p = .035]. Also significantly associated with VTE were pulmonary hypertension [p = .001, OR 23.3, 95%CI 5.18-105.06] and stroke [p = .032, OR 9.35, 95%CI 0.87-53.25].

CONCLUSION

The prevalence of VTE among SCD patients in Nigeria is low. It is significantly associated with vaso-occlusive crisis, pulmonary hypertension and stroke.