Lupus anticoagulant and leg ulcers in sickle cell anemia

Antiphospholipid Antibodies in Sickle Cell Disease: A Systematic Review and Exploratory Meta-Analysis

The relationship between antiphospholipid antibodies (aPL) and sickle cell disease (SCD) has never been systematically addressed. Our aim was to evaluate potential links between SCD and aPL in all age groups. EMBASE/PubMed was screened from inception to May 2020 and Peto odds ratios for rare events were calculated. The pooled prevalence (PP) of IgG anticardiolipin antibodies (aCL) was higher in individuals with SCD than in controls (27.9% vs 8.7%, P < 0.0001), that of IgM aCL was similar in the two groups (2.9% vs 2.7%); only individuals with SCD were positive for lupus anticoagulant (LA) (7.7% vs 0%, P < 0.0001). The PP of leg ulcers was similar between aPL positive and negative individuals (44% vs 53%) and between patients in acute crisis and stable patients (5.6% vs 7.3%). Reporting of aPL as a binary outcome and not as a titer precluded further interpretation. The results indicate that a prospective case-control study with serial measurements of a panel of aPL in SCD patients might be warranted, in order to understand further the possible pathogenic role of aPL in SCD.

Haematological indices of sickle cell patients with chronic leg ulcers on compression therapy

Background

Recurrent chronic leg ulcers and its are morbidities associated with sickle cell anaemia (SCA). Compression therapy increases the rate of healing of these ulcers and also decreases the rate of recurrence.

Objective

This study evaluated the haematological parameters of patients with SCA and chronic leg ulcers placed on high compression bandaging to provide data for improved ulcer management and prevention.

Methods

Eighteen patients with SCA and chronic leg ulcers were recruited for treatment by compression therapy in Ibadan, Nigeria, from March to June 2015. Eighteen SCA patients with no history of chronic leg ulcers were age and sex matched and recruited as controls. Blood samples, wound biopsies and swabs were collected at different time points for full blood count, microbiology, culture and antimicrobial susceptibility tests. Haemoglobin variants were quantified by high performance liquid chromatography. Fasting blood sugar was tested for leg ulcer patients to determine diabetic status.

Results

Ulcers ranged from 0.5 cm² to 416 cm² (median: 38.4 cm²). Post-intervention ulcer size ranged from 0.0 cm² to 272 cm² (median: 18.6 cm², p < 0.001); four ulcers completely healed. Compared to the control group, haematological indices at commencement of treatment were more severe in leg ulcer patients (p = 0.02). No patients with chronic leg ulcer was diabetic. Microorganisms isolated from the leg ulcers include Pseudomonas aeruginosa, Staphylococcus aureus, Proteus sp., Escherichia coli and Klebsiella oxytoca.

Conclusion

Measures to improve haematological parameters during leg ulcer treatment in SCA patients should be taken to aid wound healing.

Enhanced Hypercoagulability in Sickle Cell Anaemia Patients with Chronic Leg Ulcers

Sickle Cell Anaemia (SCA) is associated with a hypercoagulable state resulting in a predisposition to venous thromboembolism. With improvements in the quality of care, more patients with SCA survive into adulthood with an associated increase in the frequency of end-organ damage and chronic complications such as chronic leg ulcers (CLUs). These ulcers rarely occur in the first decade of life and are recurrent, painful, and slow-to-heal. This study tested the hypothesis that coagulation is enhanced in SCA patients with CLU. 145 participants (50 SCA with CLU, 50 SCA without CLU, and 45 with haemoglobin AA) were assessed to determine their coagulation profile using selected tests of coagulation. The SCA with the CLU group had the lowest mean haemoglobin (Hb) concentration. SCA patients with and without CLUs had elevated mean platelet counts, shorter mean aPTT, and marginally prolonged mean PT  compared to HbAA patients. SCA with CLUs patients had a significantly shortened aPTT than those without CLUs (p = 0.035) and HbAA (p = 0.009). There were significant differences in the mean PT between SCA with CLUs patients and HbAA (p = 0.017); SCA without CLU and HbAA (p = 0.014). SCA with and without CLUs patients had higher mean D-dimer levels compared to HbAA. There was a negative correlation between Hb concentration and duration of CLU (r = -0.331, p = 0.021). In conclusion, our study demonstrates a heightened hypercoagulability in SCA patients with CLUs. We did not test for platelet activation, and it is not clear what role, if any, the enhanced hypercoagulability plays in the pathogenesis of CLUs in SCA. It will be useful to ascertain if antiplatelet agents or/and anticoagulants quicken the healing of CLUs in SCA patients.

Association of silent infarcts in sickle cell anemia with decreased annexin A5 resistance

BACKGROUND

Sickle cell anemia (SCA) is characterized by abnormally shaped, adhesive RBCs that interact with white blood cells and the endothelium, leading to chronic hemolysis, vasculopathy and a prothrombotic state. About 10% of subjects with a thrombotic event in the general population will have an associated antiphospholipid (aPL) antibody. One proposed mechanism for the thrombophilic nature of aPL antibodies is the disruption of the potent anticoagulant annexin A5 or Annexin A5 resistance (A5R). We designed a pilot study assessing the presence of aPL antibodies and disruption of A5R in pediatric sickle cell subjects.

METHODS

39 subjects with SCA participated in this study. A5R, DRVVT, anti-β2GP1, anti-β2GP1, anti-phosphatidylserine and anti-cardiolipin antibody assays were performed.

RESULTS

There was a high prevalence of abnormal A5R despite a low prevalence of antiphospholipid antibodies. Multivariate logistic regression analyses showed an association with silent infarcts (p=0.015), lower hemoglobin (p=0.037), older age (p=0.047) and abnormal A5R.

CONCLUSION

We report an association between annexin A5 resistance and presence of silent infarct, low hemoglobin, and older age in a subgroup of SCA subjects. A potential role for perturbed A5R in the pathophysiology of SCA needs to be evaluated further.

Critical Reviews: How we treat sickle cell patients with leg ulcers

The past five decades have seen an improvement in the mortality and morbidity of sickle cell disease (SCD) because of prophylaxis against infectious complications, improved and expanded red cell transfusions, implementation of hydroxyurea therapy, and advances in supportive care. Now that the majority of patients in the western hemisphere reaches adulthood, end organ diseases are frequent, which include vasculopathic complications such as chronic leg ulcers. The management of patients with leg ulcers requires the hematologist to lead a team of health care professionals, and investigates the presence of associated, but potentially still occult signs of vasculopathy, such as pulmonary hypertension, renal disease, priapism and retinopathy. These complications may be asynchronous, and long term careful screening is indicated, in order to ensure early diagnosis and intervention. It is crucial to address both the immediate consequences of pain, infection and disability, and long term effects on quality of life, employment and stigma associated with chronic ulceration. Recent insights into their pathophysiology may have practical implications. We propose a holistic approach to the management of patients' physical and emotional problems and mechanisms of ulcers formation and delayed healing. An overview of topical and systemic therapies for chronic ulcers is given, with the understanding that wound care therapy is best left to the wound specialists, medical and surgical, with whom the hematologist must keep an open line of communication. In the absence of evidence-based guidelines, our opinion is based on both a critical review of the literature and our personal clinical and research experience.

Sickle cell disease and venous thromboembolism: what the anticoagulation expert needs to know

Venous thromboembolism (VTE) is common in patients with sickle cell disease (SCD). The etiology of increased risk of VTE in SCD patients is multifactorial and is related to both traditional factors and SCD-specific factors. Traditional risk factors such as central venous catheters, frequent hospitalization, orthopedic surgeries for avascular necrosis, and pregnancy may lead to increased incidence of VTE in the SCD population. In addition, SCD itself appears to be a hypercoagulable state, and many SCD-specific factors such as thrombophilic defects, genotype and splenectomy may modify the risk of VTE. SCD complications such as acute chest syndrome and pulmonary hypertension may also be related to VTE. Anticoagulation experts should be aware of these factors to help inform prophylaxis and treatment decisions.